cb4e1bb0b9
With the larger gap, logalloc reserved more memory for std than the background reclaim threshold for running, so it was triggered rarely. With the gap reduced, background reclaim is constantly running in an allocating workload (e.g. cache misses).
2479 lines
84 KiB
C++
2479 lines
84 KiB
C++
/*
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* Copyright (C) 2015 ScyllaDB
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*/
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/*
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* This file is part of Scylla.
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*
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* Scylla is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Scylla is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <boost/range/algorithm/heap_algorithm.hpp>
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#include <boost/range/algorithm/remove.hpp>
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#include <boost/range/algorithm.hpp>
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#include <boost/heap/binomial_heap.hpp>
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#include <boost/intrusive/list.hpp>
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#include <boost/intrusive/set.hpp>
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#include <boost/intrusive/slist.hpp>
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#include <boost/range/adaptors.hpp>
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#include <stack>
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#include <seastar/core/memory.hh>
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#include <seastar/core/align.hh>
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#include <seastar/core/print.hh>
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#include <seastar/core/metrics.hh>
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#include <seastar/core/reactor.hh>
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#include <seastar/core/coroutine.hh>
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#include <seastar/util/alloc_failure_injector.hh>
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#include <seastar/util/backtrace.hh>
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#include "utils/logalloc.hh"
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#include "log.hh"
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#include "utils/dynamic_bitset.hh"
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#include "utils/log_heap.hh"
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#include "utils/preempt.hh"
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#include <random>
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#include <chrono>
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using namespace std::chrono_literals;
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#ifdef SEASTAR_ASAN_ENABLED
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#include "sanitizer/asan_interface.h"
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// For each aligned 8 byte segment, the algorithm used by address
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// sanitizer can represent any addressable prefix followd by a
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// poisoned suffix. The details are at:
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// https://github.com/google/sanitizers/wiki/AddressSanitizerAlgorithm
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// For us this means that:
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// * The descriptor must be 8 byte aligned. If it was not, making the
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// descriptor addressable would also make the end of the previous
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// value addressable.
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// * Each value must be at least 8 byte aligned. If it was not, making
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// the value addressable would also make the end of the descriptor
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// addressable.
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namespace debug {
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constexpr size_t logalloc_alignment = 8;
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}
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template<typename T>
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[[nodiscard]] static T align_up_for_asan(T val) {
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return align_up(val, size_t(8));
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}
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template<typename T>
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void poison(const T* addr, size_t size) {
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// Both values and descriptors must be aligned.
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assert(uintptr_t(addr) % 8 == 0);
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// This can be followed by
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// * 8 byte aligned descriptor (this is a value)
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// * 8 byte aligned value
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// * dead value
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// * end of segment
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// In all cases, we can align up the size to guarantee that asan
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// is able to poison this.
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ASAN_POISON_MEMORY_REGION(addr, align_up_for_asan(size));
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}
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void unpoison(const char *addr, size_t size) {
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ASAN_UNPOISON_MEMORY_REGION(addr, size);
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}
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#else
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namespace debug {
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constexpr size_t logalloc_alignment = 1;
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}
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template<typename T>
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[[nodiscard]] static T align_up_for_asan(T val) { return val; }
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template<typename T>
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void poison(const T* addr, size_t size) { }
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void unpoison(const char *addr, size_t size) { }
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#endif
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namespace bi = boost::intrusive;
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standard_allocation_strategy standard_allocation_strategy_instance;
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namespace {
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class migrators_base {
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protected:
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std::vector<const migrate_fn_type*> _migrators;
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};
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#ifdef DEBUG_LSA_SANITIZER
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class migrators : public migrators_base, public enable_lw_shared_from_this<migrators> {
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private:
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struct backtrace_entry {
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saved_backtrace _registration;
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saved_backtrace _deregistration;
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};
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std::vector<std::unique_ptr<backtrace_entry>> _backtraces;
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static logging::logger _logger;
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private:
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void on_error() { abort(); }
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public:
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uint32_t add(const migrate_fn_type* m) {
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_migrators.push_back(m);
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_backtraces.push_back(std::make_unique<backtrace_entry>(backtrace_entry{current_backtrace(), {}}));
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return _migrators.size() - 1;
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}
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void remove(uint32_t idx) {
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if (idx >= _migrators.size()) {
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_logger.error("Attempting to deregister migrator id {} which was never registered:\n{}",
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idx, current_backtrace());
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on_error();
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}
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if (!_migrators[idx]) {
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_logger.error("Attempting to double deregister migrator id {}:\n{}\n"
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"Previously deregistered at:\n{}\nRegistered at:\n{}",
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idx, current_backtrace(), _backtraces[idx]->_deregistration,
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_backtraces[idx]->_registration);
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on_error();
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}
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_migrators[idx] = nullptr;
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_backtraces[idx]->_deregistration = current_backtrace();
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}
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const migrate_fn_type*& operator[](uint32_t idx) {
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if (idx >= _migrators.size()) {
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_logger.error("Attempting to use migrator id {} that was never registered:\n{}",
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idx, current_backtrace());
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on_error();
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}
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if (!_migrators[idx]) {
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_logger.error("Attempting to use deregistered migrator id {}:\n{}\n"
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"Deregistered at:\n{}\nRegistered at:\n{}",
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idx, current_backtrace(), _backtraces[idx]->_deregistration,
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_backtraces[idx]->_registration);
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on_error();
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}
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return _migrators[idx];
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}
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};
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logging::logger migrators::_logger("lsa-migrator-sanitizer");
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#else
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class migrators : public migrators_base, public enable_lw_shared_from_this<migrators> {
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std::vector<uint32_t> _unused_ids;
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public:
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uint32_t add(const migrate_fn_type* m) {
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if (!_unused_ids.empty()) {
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uint32_t idx = _unused_ids.back();
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_unused_ids.pop_back();
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_migrators[idx] = m;
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return idx;
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}
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_migrators.push_back(m);
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return _migrators.size() - 1;
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}
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void remove(uint32_t idx) {
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_unused_ids.push_back(idx);
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}
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const migrate_fn_type*& operator[](uint32_t idx) {
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return _migrators[idx];
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}
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};
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#endif
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static
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migrators&
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static_migrators() noexcept {
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memory::scoped_critical_alloc_section dfg;
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static thread_local lw_shared_ptr<migrators> obj = make_lw_shared<migrators>();
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return *obj;
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}
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}
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namespace debug {
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thread_local migrators* static_migrators = &::static_migrators();
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}
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uint32_t
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migrate_fn_type::register_migrator(migrate_fn_type* m) {
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auto& migrators = *debug::static_migrators;
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auto idx = migrators.add(m);
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m->_migrators = migrators.shared_from_this();
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return idx;
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}
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void
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migrate_fn_type::unregister_migrator(uint32_t index) {
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static_migrators().remove(index);
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}
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namespace logalloc {
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#ifdef DEBUG_LSA_SANITIZER
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class region_sanitizer {
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struct allocation {
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size_t size;
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saved_backtrace backtrace;
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};
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private:
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static logging::logger logger;
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bool _broken = false;
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std::unordered_map<const void*, allocation> _allocations;
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private:
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template<typename Function>
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void run_and_handle_errors(Function&& fn) noexcept {
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memory::scoped_critical_alloc_section dfg;
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if (_broken) {
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return;
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}
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try {
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fn();
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} catch (...) {
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logger.error("Internal error, disabling the sanitizer: {}", std::current_exception());
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_broken = true;
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_allocations.clear();
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}
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}
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private:
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void on_error() { abort(); }
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public:
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void on_region_destruction() noexcept {
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run_and_handle_errors([&] {
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if (_allocations.empty()) {
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return;
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}
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for (auto [ptr, alloc] : _allocations) {
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logger.error("Leaked {} byte object at {} allocated from:\n{}",
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alloc.size, ptr, alloc.backtrace);
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}
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on_error();
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});
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}
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void on_allocation(const void* ptr, size_t size) noexcept {
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run_and_handle_errors([&] {
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auto [ it, success ] = _allocations.emplace(ptr, allocation { size, current_backtrace() });
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if (!success) {
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logger.error("Attempting to allocate an {} byte object at an already occupied address {}:\n{}\n"
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"Previous allocation of {} bytes:\n{}",
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ptr, size, current_backtrace(), it->second.size, it->second.backtrace);
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on_error();
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}
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});
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}
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void on_free(const void* ptr, size_t size) noexcept {
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run_and_handle_errors([&] {
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auto it = _allocations.find(ptr);
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if (it == _allocations.end()) {
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logger.error("Attempting to free an object at {} (size: {}) that does not exist\n{}",
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ptr, size, current_backtrace());
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on_error();
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}
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if (it->second.size != size) {
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logger.error("Mismatch between allocation and deallocation size of object at {}: {} vs. {}:\n{}\n"
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"Allocated at:\n{}",
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ptr, it->second.size, size, current_backtrace(), it->second.backtrace);
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on_error();
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}
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_allocations.erase(it);
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});
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}
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void on_migrate(const void* src, size_t size, const void* dst) noexcept {
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run_and_handle_errors([&] {
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auto it_src = _allocations.find(src);
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if (it_src == _allocations.end()) {
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logger.error("Attempting to migrate an object at {} (size: {}) that does not exist",
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src, size);
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on_error();
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}
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if (it_src->second.size != size) {
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logger.error("Mismatch between allocation and migration size of object at {}: {} vs. {}\n"
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"Allocated at:\n{}",
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src, it_src->second.size, size, it_src->second.backtrace);
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on_error();
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}
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auto [ it_dst, success ] = _allocations.emplace(dst, std::move(it_src->second));
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if (!success) {
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logger.error("Attempting to migrate an {} byte object to an already occupied address {}:\n"
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"Migrated object allocated from:\n{}\n"
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"Previous allocation of {} bytes at the destination:\n{}",
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size, dst, it_src->second.backtrace, it_dst->second.size, it_dst->second.backtrace);
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on_error();
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}
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_allocations.erase(it_src);
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});
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}
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void merge(region_sanitizer& other) noexcept {
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run_and_handle_errors([&] {
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_broken = other._broken;
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if (_broken) {
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_allocations.clear();
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} else {
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_allocations.merge(other._allocations);
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if (!other._allocations.empty()) {
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for (auto [ptr, o_alloc] : other._allocations) {
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auto& alloc = _allocations.at(ptr);
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logger.error("Conflicting allocations at address {} in merged regions\n"
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"{} bytes allocated from:\n{}\n"
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"{} bytes allocated from:\n{}",
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ptr, alloc.size, alloc.backtrace, o_alloc.size, o_alloc.backtrace);
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}
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on_error();
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}
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}
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});
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}
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};
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logging::logger region_sanitizer::logger("lsa-sanitizer");
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#else
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struct region_sanitizer {
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void on_region_destruction() noexcept { }
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void on_allocation(const void*, size_t) noexcept { }
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void on_free(const void* ptr, size_t size) noexcept { }
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void on_migrate(const void*, size_t, const void*) noexcept { }
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void merge(region_sanitizer&) noexcept { }
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};
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#endif
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struct segment;
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static logging::logger llogger("lsa");
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static logging::logger timing_logger("lsa-timing");
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static tracker& get_tracker_instance() noexcept {
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memory::scoped_critical_alloc_section dfg;
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static thread_local tracker obj;
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return obj;
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}
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static thread_local tracker& tracker_instance = get_tracker_instance();
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using clock = std::chrono::steady_clock;
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class background_reclaimer {
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scheduling_group _sg;
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noncopyable_function<void (size_t target)> _reclaim;
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timer<lowres_clock> _adjust_shares_timer;
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// If engaged, main loop is not running, set_value() to wake it.
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promise<>* _main_loop_wait = nullptr;
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future<> _done;
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bool _stopping = false;
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static constexpr size_t free_memory_threshold = 60'000'000;
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private:
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bool have_work() const {
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#ifndef SEASTAR_DEFAULT_ALLOCATOR
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return memory::stats().free_memory() < free_memory_threshold;
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#else
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return false;
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#endif
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}
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void main_loop_wake() {
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llogger.debug("background_reclaimer::main_loop_wake: waking {}", bool(_main_loop_wait));
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if (_main_loop_wait) {
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_main_loop_wait->set_value();
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_main_loop_wait = nullptr;
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}
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}
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future<> main_loop() {
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llogger.debug("background_reclaimer::main_loop: entry");
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while (true) {
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while (!_stopping && !have_work()) {
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promise<> wait;
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_main_loop_wait = &wait;
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llogger.trace("background_reclaimer::main_loop: sleep");
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co_await wait.get_future();
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llogger.trace("background_reclaimer::main_loop: awakened");
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_main_loop_wait = nullptr;
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}
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if (_stopping) {
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break;
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}
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_reclaim(free_memory_threshold - memory::stats().free_memory());
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co_await make_ready_future<>();
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}
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llogger.debug("background_reclaimer::main_loop: exit");
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}
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void adjust_shares() {
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if (_main_loop_wait && have_work()) {
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_sg.set_shares(1 + (1000 * (free_memory_threshold - memory::stats().free_memory())) / free_memory_threshold);
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main_loop_wake();
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}
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}
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public:
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explicit background_reclaimer(scheduling_group sg, noncopyable_function<void (size_t target)> reclaim)
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: _sg(sg)
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, _reclaim(std::move(reclaim))
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, _adjust_shares_timer(_sg, [this] { adjust_shares(); })
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, _done(with_scheduling_group(_sg, [this] { return main_loop(); })) {
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if (sg != default_scheduling_group()) {
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_adjust_shares_timer.arm_periodic(50ms);
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}
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}
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future<> stop() {
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_stopping = true;
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main_loop_wake();
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return std::move(_done);
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}
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};
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|
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class tracker::impl {
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std::optional<background_reclaimer> _background_reclaimer;
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std::vector<region::impl*> _regions;
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seastar::metrics::metric_groups _metrics;
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bool _reclaiming_enabled = true;
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size_t _reclamation_step = 1;
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bool _abort_on_bad_alloc = false;
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private:
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// Prevents tracker's reclaimer from running while live. Reclaimer may be
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// invoked synchronously with allocator. This guard ensures that this
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// object is not re-entered while inside one of the tracker's methods.
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struct reclaiming_lock {
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impl& _ref;
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bool _prev;
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reclaiming_lock(impl& ref)
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: _ref(ref)
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, _prev(ref._reclaiming_enabled)
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{
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_ref._reclaiming_enabled = false;
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}
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~reclaiming_lock() {
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_ref._reclaiming_enabled = _prev;
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}
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};
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friend class tracker_reclaimer_lock;
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|
public:
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impl();
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|
~impl();
|
|
future<> stop() {
|
|
if (_background_reclaimer) {
|
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return _background_reclaimer->stop();
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} else {
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return make_ready_future<>();
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}
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}
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void register_region(region::impl*);
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void unregister_region(region::impl*) noexcept;
|
|
size_t reclaim(size_t bytes, is_preemptible p);
|
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// Compacts one segment at a time from sparsest segment to least sparse until work_waiting_on_reactor returns true
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// or there are no more segments to compact.
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idle_cpu_handler_result compact_on_idle(work_waiting_on_reactor check_for_work);
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// Releases whole segments back to the segment pool.
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// After the call, if there is enough evictable memory, the amount of free segments in the pool
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// will be at least reserve_segments + div_ceil(bytes, segment::size).
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// Returns the amount by which segment_pool.total_memory_in_use() has decreased.
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size_t compact_and_evict(size_t reserve_segments, size_t bytes, is_preemptible p);
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void full_compaction();
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void reclaim_all_free_segments();
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occupancy_stats region_occupancy();
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occupancy_stats occupancy();
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size_t non_lsa_used_space();
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// Set the minimum number of segments reclaimed during single reclamation cycle.
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void set_reclamation_step(size_t step_in_segments) { _reclamation_step = step_in_segments; }
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size_t reclamation_step() const { return _reclamation_step; }
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// Abort on allocation failure from LSA
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void enable_abort_on_bad_alloc() { _abort_on_bad_alloc = true; }
|
|
bool should_abort_on_bad_alloc() const { return _abort_on_bad_alloc; }
|
|
void setup_background_reclaim(scheduling_group sg) {
|
|
assert(!_background_reclaimer);
|
|
_background_reclaimer.emplace(sg, [this] (size_t target) {
|
|
reclaim(target, is_preemptible::yes);
|
|
});
|
|
}
|
|
private:
|
|
// Like compact_and_evict() but assumes that reclaim_lock is held around the operation.
|
|
size_t compact_and_evict_locked(size_t reserve_segments, size_t bytes, is_preemptible preempt);
|
|
};
|
|
|
|
class tracker_reclaimer_lock {
|
|
tracker::impl::reclaiming_lock _lock;
|
|
public:
|
|
tracker_reclaimer_lock() : _lock(shard_tracker().get_impl()) { }
|
|
};
|
|
|
|
tracker::tracker()
|
|
: _impl(std::make_unique<impl>())
|
|
, _reclaimer([this] (seastar::memory::reclaimer::request r) { return reclaim(r); }, memory::reclaimer_scope::sync)
|
|
{ }
|
|
|
|
tracker::~tracker() {
|
|
}
|
|
|
|
future<>
|
|
tracker::stop() {
|
|
return _impl->stop();
|
|
}
|
|
|
|
size_t tracker::reclaim(size_t bytes) {
|
|
return _impl->reclaim(bytes, is_preemptible::no);
|
|
}
|
|
|
|
occupancy_stats tracker::region_occupancy() {
|
|
return _impl->region_occupancy();
|
|
}
|
|
|
|
occupancy_stats tracker::occupancy() {
|
|
return _impl->occupancy();
|
|
}
|
|
|
|
size_t tracker::non_lsa_used_space() const {
|
|
return _impl->non_lsa_used_space();
|
|
}
|
|
|
|
void tracker::full_compaction() {
|
|
return _impl->full_compaction();
|
|
}
|
|
|
|
void tracker::reclaim_all_free_segments() {
|
|
return _impl->reclaim_all_free_segments();
|
|
}
|
|
|
|
tracker& shard_tracker() {
|
|
return tracker_instance;
|
|
}
|
|
|
|
struct alignas(segment_size) segment {
|
|
static constexpr int size_shift = segment_size_shift;
|
|
using size_type = std::conditional_t<(size_shift < 16), uint16_t, uint32_t>;
|
|
static constexpr size_t size = segment_size;
|
|
|
|
uint8_t data[size];
|
|
|
|
segment() noexcept { }
|
|
|
|
template<typename T = void>
|
|
const T* at(size_t offset) const {
|
|
return reinterpret_cast<const T*>(data + offset);
|
|
}
|
|
|
|
template<typename T = void>
|
|
T* at(size_t offset) {
|
|
return reinterpret_cast<T*>(data + offset);
|
|
}
|
|
|
|
bool is_empty();
|
|
void record_alloc(size_type size);
|
|
void record_free(size_type size);
|
|
occupancy_stats occupancy();
|
|
|
|
static void* operator new(size_t size) = delete;
|
|
static void* operator new(size_t, void* ptr) noexcept { return ptr; }
|
|
static void operator delete(void* ptr) = delete;
|
|
};
|
|
|
|
static constexpr size_t max_managed_object_size = segment_size * 0.1;
|
|
static constexpr auto max_used_space_ratio_for_compaction = 0.85;
|
|
static constexpr size_t max_used_space_for_compaction = segment_size * max_used_space_ratio_for_compaction;
|
|
static constexpr size_t min_free_space_for_compaction = segment_size - max_used_space_for_compaction;
|
|
|
|
static_assert(min_free_space_for_compaction >= max_managed_object_size,
|
|
"Segments which cannot fit max_managed_object_size must not be considered compactible for the sake of forward progress of compaction");
|
|
|
|
// Since we only compact if there's >= min_free_space_for_compaction of free space,
|
|
// we use min_free_space_for_compaction as the histogram's minimum size and put
|
|
// everything below that value in the same bucket.
|
|
extern constexpr log_heap_options segment_descriptor_hist_options(min_free_space_for_compaction, 3, segment_size);
|
|
|
|
struct segment_descriptor : public log_heap_hook<segment_descriptor_hist_options> {
|
|
segment::size_type _free_space;
|
|
region::impl* _region;
|
|
|
|
segment_descriptor()
|
|
: _region(nullptr)
|
|
{ }
|
|
|
|
bool is_empty() const {
|
|
return _free_space == segment::size;
|
|
}
|
|
|
|
occupancy_stats occupancy() const {
|
|
return { _free_space, segment::size };
|
|
}
|
|
|
|
void record_alloc(segment::size_type size) {
|
|
_free_space -= size;
|
|
}
|
|
|
|
void record_free(segment::size_type size) {
|
|
_free_space += size;
|
|
}
|
|
};
|
|
|
|
using segment_descriptor_hist = log_heap<segment_descriptor, segment_descriptor_hist_options>;
|
|
|
|
#ifndef SEASTAR_DEFAULT_ALLOCATOR
|
|
class segment_store {
|
|
memory::memory_layout _layout;
|
|
uintptr_t _segments_base; // The address of the first segment
|
|
|
|
public:
|
|
size_t non_lsa_reserve = 0;
|
|
segment_store()
|
|
: _layout(memory::get_memory_layout())
|
|
, _segments_base(align_down(_layout.start, (uintptr_t)segment::size)) {
|
|
}
|
|
segment* segment_from_idx(size_t idx) const {
|
|
return reinterpret_cast<segment*>(_segments_base) + idx;
|
|
}
|
|
size_t idx_from_segment(segment* seg) const {
|
|
return seg - reinterpret_cast<segment*>(_segments_base);
|
|
}
|
|
size_t new_idx_for_segment(segment* seg) {
|
|
return idx_from_segment(seg);
|
|
}
|
|
void free_segment(segment *seg) { }
|
|
size_t max_segments() const {
|
|
return (_layout.end - _segments_base) / segment::size;
|
|
}
|
|
bool can_allocate_more_segments() {
|
|
return memory::stats().free_memory() >= non_lsa_reserve + segment::size;
|
|
}
|
|
};
|
|
#else
|
|
class segment_store {
|
|
std::vector<segment*> _segments;
|
|
std::unordered_map<segment*, size_t> _segment_indexes;
|
|
static constexpr size_t _std_memory_available = size_t(1) << 30; // emulate 1GB per shard
|
|
std::vector<segment*>::iterator find_empty() {
|
|
// segment 0 is a marker for no segment
|
|
return std::find(_segments.begin() + 1, _segments.end(), nullptr);
|
|
}
|
|
|
|
public:
|
|
size_t non_lsa_reserve = 0;
|
|
segment_store() : _segments(max_segments()) {
|
|
_segment_indexes.reserve(max_segments());
|
|
}
|
|
segment* segment_from_idx(size_t idx) const {
|
|
assert(idx < _segments.size());
|
|
return _segments[idx];
|
|
}
|
|
size_t idx_from_segment(segment* seg) {
|
|
// segment 0 is a marker for no segment
|
|
auto i = _segment_indexes.find(seg);
|
|
if (i == _segment_indexes.end()) {
|
|
return 0;
|
|
}
|
|
return i->second;
|
|
}
|
|
size_t new_idx_for_segment(segment* seg) {
|
|
auto i = find_empty();
|
|
assert(i != _segments.end());
|
|
*i = seg;
|
|
size_t ret = i - _segments.begin();
|
|
_segment_indexes[seg] = ret;
|
|
return ret;
|
|
}
|
|
void free_segment(segment *seg) {
|
|
size_t i = idx_from_segment(seg);
|
|
assert(i != 0);
|
|
_segment_indexes.erase(seg);
|
|
_segments[i] = nullptr;
|
|
}
|
|
~segment_store() {
|
|
for (segment *seg : _segments) {
|
|
if (seg) {
|
|
seg->~segment();
|
|
free(seg);
|
|
}
|
|
}
|
|
}
|
|
size_t max_segments() const {
|
|
return _std_memory_available / segment::size;
|
|
}
|
|
bool can_allocate_more_segments() {
|
|
auto i = find_empty();
|
|
return i != _segments.end();
|
|
}
|
|
};
|
|
#endif
|
|
|
|
// Segment pool implementation for the seastar allocator.
|
|
// Stores segment descriptors in a vector which is indexed using most significant
|
|
// bits of segment address.
|
|
//
|
|
// We prefer using high-address segments, and returning low-address segments to the seastar
|
|
// allocator in order to segregate lsa and non-lsa memory, to reduce fragmentation.
|
|
class segment_pool {
|
|
segment_store _store;
|
|
std::vector<segment_descriptor> _segments;
|
|
size_t _segments_in_use{};
|
|
utils::dynamic_bitset _lsa_owned_segments_bitmap; // owned by this
|
|
utils::dynamic_bitset _lsa_free_segments_bitmap; // owned by this, but not in use
|
|
size_t _free_segments = 0;
|
|
size_t _current_emergency_reserve_goal = 1;
|
|
size_t _emergency_reserve_max = 30;
|
|
bool _allocation_failure_flag = false;
|
|
bool _allocation_enabled = true;
|
|
|
|
struct allocation_lock {
|
|
segment_pool& _pool;
|
|
bool _prev;
|
|
allocation_lock(segment_pool& p)
|
|
: _pool(p)
|
|
, _prev(p._allocation_enabled)
|
|
{
|
|
_pool._allocation_enabled = false;
|
|
}
|
|
~allocation_lock() {
|
|
_pool._allocation_enabled = _prev;
|
|
}
|
|
};
|
|
|
|
size_t _non_lsa_memory_in_use = 0;
|
|
// Invariants - a segment is in one of the following states:
|
|
// In use by some region
|
|
// - set in _lsa_owned_segments_bitmap
|
|
// - clear in _lsa_free_segments_bitmap
|
|
// - counted in _segments_in_use
|
|
// Free:
|
|
// - set in _lsa_owned_segments_bitmap
|
|
// - set in _lsa_free_segments_bitmap
|
|
// - counted in _unreserved_free_segments
|
|
// Non-lsa:
|
|
// - clear everywhere
|
|
private:
|
|
segment* allocate_segment(size_t reserve);
|
|
void deallocate_segment(segment* seg);
|
|
friend void* segment::operator new(size_t);
|
|
friend void segment::operator delete(void*);
|
|
|
|
segment* allocate_or_fallback_to_reserve();
|
|
void free_or_restore_to_reserve(segment* seg) noexcept;
|
|
segment* segment_from_idx(size_t idx) const {
|
|
return _store.segment_from_idx(idx);
|
|
}
|
|
size_t idx_from_segment(segment* seg) {
|
|
return _store.idx_from_segment(seg);
|
|
}
|
|
size_t max_segments() const {
|
|
return _store.max_segments();
|
|
}
|
|
bool can_allocate_more_segments() {
|
|
return _allocation_enabled && _store.can_allocate_more_segments();
|
|
}
|
|
bool compact_segment(segment* seg);
|
|
public:
|
|
segment_pool();
|
|
void prime(size_t available_memory, size_t min_free_memory);
|
|
segment* new_segment(region::impl* r);
|
|
segment_descriptor& descriptor(segment*);
|
|
// Returns segment containing given object or nullptr.
|
|
segment* containing_segment(const void* obj);
|
|
segment* segment_from(const segment_descriptor& desc);
|
|
void free_segment(segment*) noexcept;
|
|
void free_segment(segment*, segment_descriptor&) noexcept;
|
|
size_t segments_in_use() const;
|
|
size_t current_emergency_reserve_goal() const { return _current_emergency_reserve_goal; }
|
|
void set_emergency_reserve_max(size_t new_size) { _emergency_reserve_max = new_size; }
|
|
size_t emergency_reserve_max() { return _emergency_reserve_max; }
|
|
void set_current_emergency_reserve_goal(size_t goal) { _current_emergency_reserve_goal = goal; }
|
|
void clear_allocation_failure_flag() { _allocation_failure_flag = false; }
|
|
bool allocation_failure_flag() { return _allocation_failure_flag; }
|
|
void refill_emergency_reserve();
|
|
void update_non_lsa_memory_in_use(ssize_t n) {
|
|
_non_lsa_memory_in_use += n;
|
|
}
|
|
size_t non_lsa_memory_in_use() const {
|
|
return _non_lsa_memory_in_use;
|
|
}
|
|
size_t total_memory_in_use() const {
|
|
return _non_lsa_memory_in_use + _segments_in_use * segment::size;
|
|
}
|
|
size_t total_free_memory() const {
|
|
return _free_segments * segment::size;
|
|
}
|
|
struct reservation_goal;
|
|
void set_region(segment* seg, region::impl* r) {
|
|
set_region(descriptor(seg), r);
|
|
}
|
|
void set_region(segment_descriptor& desc, region::impl* r) {
|
|
desc._region = r;
|
|
}
|
|
size_t reclaim_segments(size_t target, is_preemptible preempt);
|
|
void reclaim_all_free_segments() {
|
|
reclaim_segments(std::numeric_limits<size_t>::max(), is_preemptible::no);
|
|
}
|
|
|
|
struct stats {
|
|
size_t segments_compacted;
|
|
uint64_t memory_allocated;
|
|
uint64_t memory_compacted;
|
|
};
|
|
private:
|
|
stats _stats{};
|
|
public:
|
|
const stats& statistics() const { return _stats; }
|
|
void on_segment_compaction(size_t used_size);
|
|
void on_memory_allocation(size_t size);
|
|
size_t unreserved_free_segments() const { return _free_segments - std::min(_free_segments, _emergency_reserve_max); }
|
|
size_t free_segments() const { return _free_segments; }
|
|
};
|
|
|
|
size_t segment_pool::reclaim_segments(size_t target, is_preemptible preempt) {
|
|
// Reclaimer tries to release segments occupying lower parts of the address
|
|
// space.
|
|
|
|
llogger.debug("Trying to reclaim {} segments", target);
|
|
|
|
// Reclamation. Migrate segments to higher addresses and shrink segment pool.
|
|
size_t reclaimed_segments = 0;
|
|
|
|
// We may fail to reclaim because a region has reclaim disabled (usually because
|
|
// it is in an allocating_section. Failed reclaims can cause high CPU usage
|
|
// if all of the lower addresses happen to be in a reclaim-disabled region (this
|
|
// is somewhat mitigated by the fact that checking for reclaim disabled is very
|
|
// cheap), but worse, failing a segment reclaim can lead to reclaimed memory
|
|
// being fragmented. This results in the original allocation continuing to fail.
|
|
//
|
|
// To combat that, we limit the number of failed reclaims. If we reach the limit,
|
|
// we fail the reclaim. The surrounding allocating_section will release the
|
|
// reclaim_lock, and increase reserves, which will result in reclaim being
|
|
// retried with all regions being reclaimable, and succeed in allocating
|
|
// contiguous memory.
|
|
size_t failed_reclaims_allowance = 10;
|
|
|
|
for (size_t src_idx = _lsa_owned_segments_bitmap.find_first_set();
|
|
reclaimed_segments != target && src_idx != utils::dynamic_bitset::npos
|
|
&& _free_segments > _current_emergency_reserve_goal;
|
|
src_idx = _lsa_owned_segments_bitmap.find_next_set(src_idx)) {
|
|
auto src = segment_from_idx(src_idx);
|
|
if (!_lsa_free_segments_bitmap.test(src_idx)) {
|
|
if (!compact_segment(src)) {
|
|
if (--failed_reclaims_allowance == 0) {
|
|
break;
|
|
}
|
|
continue;
|
|
}
|
|
}
|
|
_lsa_free_segments_bitmap.clear(src_idx);
|
|
_lsa_owned_segments_bitmap.clear(src_idx);
|
|
_store.free_segment(src);
|
|
src->~segment();
|
|
::free(src);
|
|
++reclaimed_segments;
|
|
--_free_segments;
|
|
if (preempt && need_preempt()) {
|
|
break;
|
|
}
|
|
}
|
|
|
|
llogger.debug("Reclaimed {} segments (requested {})", reclaimed_segments, target);
|
|
return reclaimed_segments;
|
|
}
|
|
|
|
segment* segment_pool::allocate_segment(size_t reserve)
|
|
{
|
|
//
|
|
// When allocating a segment we want to avoid:
|
|
// - LSA and general-purpose allocator shouldn't constantly fight each
|
|
// other for every last bit of memory
|
|
//
|
|
// allocate_segment() always works with LSA reclaimer disabled.
|
|
// 1. Firstly, the algorithm tries to allocate an lsa-owned but free segment
|
|
// 2. If no free segmented is available, a new segment is allocated from the
|
|
// system allocator. However, if the free memory is below set threshold
|
|
// this step is skipped.
|
|
// 3. Finally, the algorithm ties to compact and evict data stored in LSA
|
|
// memory in order to reclaim enough segments.
|
|
//
|
|
do {
|
|
tracker_reclaimer_lock rl;
|
|
if (_free_segments > reserve) {
|
|
auto free_idx = _lsa_free_segments_bitmap.find_last_set();
|
|
_lsa_free_segments_bitmap.clear(free_idx);
|
|
auto seg = segment_from_idx(free_idx);
|
|
--_free_segments;
|
|
return seg;
|
|
}
|
|
if (can_allocate_more_segments()) {
|
|
memory::disable_abort_on_alloc_failure_temporarily dfg;
|
|
auto p = aligned_alloc(segment::size, segment::size);
|
|
if (!p) {
|
|
continue;
|
|
}
|
|
auto seg = new (p) segment;
|
|
poison(seg, sizeof(segment));
|
|
auto idx = _store.new_idx_for_segment(seg);
|
|
_lsa_owned_segments_bitmap.set(idx);
|
|
return seg;
|
|
}
|
|
} while (shard_tracker().get_impl().compact_and_evict(reserve, shard_tracker().reclamation_step() * segment::size, is_preemptible::no));
|
|
return nullptr;
|
|
}
|
|
|
|
void segment_pool::deallocate_segment(segment* seg)
|
|
{
|
|
assert(_lsa_owned_segments_bitmap.test(idx_from_segment(seg)));
|
|
_lsa_free_segments_bitmap.set(idx_from_segment(seg));
|
|
_free_segments++;
|
|
}
|
|
|
|
void segment_pool::refill_emergency_reserve() {
|
|
while (_free_segments < _emergency_reserve_max) {
|
|
auto seg = allocate_segment(_emergency_reserve_max);
|
|
if (!seg) {
|
|
throw std::bad_alloc();
|
|
}
|
|
++_segments_in_use;
|
|
free_segment(seg);
|
|
}
|
|
}
|
|
|
|
segment_descriptor&
|
|
segment_pool::descriptor(segment* seg) {
|
|
uintptr_t index = idx_from_segment(seg);
|
|
return _segments[index];
|
|
}
|
|
|
|
segment*
|
|
segment_pool::containing_segment(const void* obj) {
|
|
auto addr = reinterpret_cast<uintptr_t>(obj);
|
|
auto offset = addr & (segment::size - 1);
|
|
auto seg = reinterpret_cast<segment*>(addr - offset);
|
|
auto index = idx_from_segment(seg);
|
|
auto& desc = _segments[index];
|
|
if (desc._region) {
|
|
return seg;
|
|
} else {
|
|
return nullptr;
|
|
}
|
|
}
|
|
|
|
segment*
|
|
segment_pool::segment_from(const segment_descriptor& desc) {
|
|
assert(desc._region);
|
|
auto index = &desc - &_segments[0];
|
|
return segment_from_idx(index);
|
|
}
|
|
|
|
segment*
|
|
segment_pool::allocate_or_fallback_to_reserve() {
|
|
auto seg = allocate_segment(_current_emergency_reserve_goal);
|
|
if (!seg) {
|
|
_allocation_failure_flag = true;
|
|
throw std::bad_alloc();
|
|
}
|
|
return seg;
|
|
}
|
|
|
|
segment*
|
|
segment_pool::new_segment(region::impl* r) {
|
|
auto seg = allocate_or_fallback_to_reserve();
|
|
++_segments_in_use;
|
|
segment_descriptor& desc = descriptor(seg);
|
|
desc._free_space = segment::size;
|
|
desc._region = r;
|
|
return seg;
|
|
}
|
|
|
|
void segment_pool::free_segment(segment* seg) noexcept {
|
|
free_segment(seg, descriptor(seg));
|
|
}
|
|
|
|
void segment_pool::free_segment(segment* seg, segment_descriptor& desc) noexcept {
|
|
llogger.trace("Releasing segment {}", fmt::ptr(seg));
|
|
desc._region = nullptr;
|
|
deallocate_segment(seg);
|
|
--_segments_in_use;
|
|
}
|
|
|
|
segment_pool::segment_pool()
|
|
: _segments(max_segments())
|
|
, _lsa_owned_segments_bitmap(max_segments())
|
|
, _lsa_free_segments_bitmap(max_segments())
|
|
{
|
|
}
|
|
|
|
void segment_pool::prime(size_t available_memory, size_t min_free_memory) {
|
|
auto old_emergency_reserve = std::exchange(_emergency_reserve_max, std::numeric_limits<size_t>::max());
|
|
try {
|
|
// Allocate all of memory so that we occupy the top part. Afterwards, we'll start
|
|
// freeing from the bottom.
|
|
_store.non_lsa_reserve = 0;
|
|
refill_emergency_reserve();
|
|
} catch (std::bad_alloc&) {
|
|
_emergency_reserve_max = old_emergency_reserve;
|
|
}
|
|
// We want to leave more free memory than just min_free_memory() in order to reduce
|
|
// the frequency of expensive segment-migrating reclaim() called by the seastar allocator.
|
|
size_t min_gap = 1 * 1024 * 1024;
|
|
size_t max_gap = 32 * 1024 * 1024;
|
|
size_t gap = std::min(max_gap, std::max(available_memory / 16, min_gap));
|
|
_store.non_lsa_reserve = min_free_memory + gap;
|
|
// Since the reclaimer is not yet in place, free some low memory for general use
|
|
reclaim_segments(_store.non_lsa_reserve / segment::size, is_preemptible::no);
|
|
}
|
|
|
|
void segment_pool::on_segment_compaction(size_t used_size) {
|
|
_stats.segments_compacted++;
|
|
_stats.memory_compacted += used_size;
|
|
}
|
|
|
|
void segment_pool::on_memory_allocation(size_t size) {
|
|
_stats.memory_allocated += size;
|
|
}
|
|
|
|
// RAII wrapper to maintain segment_pool::current_emergency_reserve_goal()
|
|
class segment_pool::reservation_goal {
|
|
segment_pool& _sp;
|
|
size_t _old_goal;
|
|
public:
|
|
reservation_goal(segment_pool& sp, size_t goal)
|
|
: _sp(sp), _old_goal(_sp.current_emergency_reserve_goal()) {
|
|
_sp.set_current_emergency_reserve_goal(goal);
|
|
}
|
|
~reservation_goal() {
|
|
_sp.set_current_emergency_reserve_goal(_old_goal);
|
|
}
|
|
};
|
|
|
|
size_t segment_pool::segments_in_use() const {
|
|
return _segments_in_use;
|
|
}
|
|
|
|
static segment_pool& get_shard_segment_pool() noexcept {
|
|
memory::scoped_critical_alloc_section dfg;
|
|
static thread_local segment_pool obj;
|
|
return obj;
|
|
}
|
|
|
|
static thread_local segment_pool& shard_segment_pool = get_shard_segment_pool();
|
|
|
|
void segment::record_alloc(segment::size_type size) {
|
|
shard_segment_pool.descriptor(this).record_alloc(size);
|
|
}
|
|
|
|
void segment::record_free(segment::size_type size) {
|
|
shard_segment_pool.descriptor(this).record_free(size);
|
|
}
|
|
|
|
bool segment::is_empty() {
|
|
return shard_segment_pool.descriptor(this).is_empty();
|
|
}
|
|
|
|
occupancy_stats
|
|
segment::occupancy() {
|
|
return { shard_segment_pool.descriptor(this)._free_space, segment::size };
|
|
}
|
|
|
|
//
|
|
// For interface documentation see logalloc::region and allocation_strategy.
|
|
//
|
|
// Allocation dynamics.
|
|
//
|
|
// Objects are allocated inside fixed-size segments. Objects don't cross
|
|
// segment boundary. Active allocations are served from a single segment using
|
|
// bump-the-pointer method. That segment is called the active segment. When
|
|
// active segment fills up, it is closed. Closed segments are kept in a heap
|
|
// which orders them by occupancy. As objects are freed, the segment become
|
|
// sparser and are eventually released. Objects which are too large are
|
|
// allocated using standard allocator.
|
|
//
|
|
// Segment layout.
|
|
//
|
|
// Objects in a segment are laid out sequentially. Each object is preceded by
|
|
// a descriptor (see object_descriptor). Object alignment is respected, so if
|
|
// there is a gap between the end of current object and the next object's
|
|
// descriptor, a trunk of the object descriptor is left right after the
|
|
// current object with the flags byte indicating the amount of padding.
|
|
//
|
|
// Per-segment metadata is kept in a separate array, managed by segment_pool
|
|
// object.
|
|
//
|
|
class region_impl final : public basic_region_impl {
|
|
// Serialized object descriptor format:
|
|
// byte0 byte1 ... byte[n-1]
|
|
// bit0-bit5: ULEB64 significand
|
|
// bit6: 1 iff first byte
|
|
// bit7: 1 iff last byte
|
|
// This format allows decoding both forwards and backwards (by scanning for bit7/bit6 respectively);
|
|
// backward decoding is needed to recover the descriptor from the object pointer when freeing.
|
|
//
|
|
// Significand interpretation (value = n):
|
|
// even: dead object, size n/2 (including descriptor)
|
|
// odd: migrate_fn_type at index n/2, from static_migrators()
|
|
class object_descriptor {
|
|
private:
|
|
uint32_t _n;
|
|
private:
|
|
explicit object_descriptor(uint32_t n) : _n(n) {}
|
|
public:
|
|
object_descriptor(allocation_strategy::migrate_fn migrator)
|
|
: _n(migrator->index() * 2 + 1)
|
|
{ }
|
|
|
|
static object_descriptor make_dead(size_t size) {
|
|
return object_descriptor(size * 2);
|
|
}
|
|
|
|
allocation_strategy::migrate_fn migrator() const {
|
|
return static_migrators()[_n / 2];
|
|
}
|
|
|
|
uint8_t alignment() const {
|
|
return migrator()->align();
|
|
}
|
|
|
|
// excluding descriptor
|
|
segment::size_type live_size(const void* obj) const {
|
|
return migrator()->size(obj);
|
|
}
|
|
|
|
// including descriptor
|
|
segment::size_type dead_size() const {
|
|
return _n / 2;
|
|
}
|
|
|
|
bool is_live() const {
|
|
return (_n & 1) == 1;
|
|
}
|
|
|
|
segment::size_type encoded_size() const {
|
|
return log2floor(_n) / 6 + 1; // 0 is illegal
|
|
}
|
|
|
|
void encode(char*& pos) const {
|
|
uint64_t b = 64;
|
|
auto n = _n;
|
|
auto start = pos;
|
|
do {
|
|
b |= n & 63;
|
|
n >>= 6;
|
|
if (!n) {
|
|
b |= 128;
|
|
}
|
|
unpoison(pos, 1);
|
|
*pos++ = b;
|
|
b = 0;
|
|
} while (n);
|
|
poison(start, pos - start);
|
|
}
|
|
|
|
// non-canonical encoding to allow padding (for alignment); encoded_size must be
|
|
// sufficient (greater than this->encoded_size())
|
|
void encode(char*& pos, size_t encoded_size) const {
|
|
uint64_t b = 64;
|
|
auto start = pos;
|
|
unpoison(start, encoded_size);
|
|
auto n = _n;
|
|
do {
|
|
b |= n & 63;
|
|
n >>= 6;
|
|
if (!--encoded_size) {
|
|
b |= 128;
|
|
}
|
|
*pos++ = b;
|
|
b = 0;
|
|
} while (encoded_size);
|
|
poison(start, pos - start);
|
|
}
|
|
|
|
static object_descriptor decode_forwards(const char*& pos) {
|
|
unsigned n = 0;
|
|
unsigned shift = 0;
|
|
auto p = pos; // avoid aliasing; p++ doesn't touch memory
|
|
uint8_t b;
|
|
do {
|
|
unpoison(p, 1);
|
|
b = *p++;
|
|
if (shift < 32) {
|
|
// non-canonical encoding can cause large shift; undefined in C++
|
|
n |= uint32_t(b & 63) << shift;
|
|
}
|
|
shift += 6;
|
|
} while ((b & 128) == 0);
|
|
poison(pos, p - pos);
|
|
pos = p;
|
|
return object_descriptor(n);
|
|
}
|
|
|
|
static object_descriptor decode_backwards(const char*& pos) {
|
|
unsigned n = 0;
|
|
uint8_t b;
|
|
auto p = pos; // avoid aliasing; --p doesn't touch memory
|
|
do {
|
|
--p;
|
|
unpoison(p, 1);
|
|
b = *p;
|
|
n = (n << 6) | (b & 63);
|
|
} while ((b & 64) == 0);
|
|
poison(p, pos - p);
|
|
pos = p;
|
|
return object_descriptor(n);
|
|
}
|
|
|
|
friend std::ostream& operator<<(std::ostream& out, const object_descriptor& desc) {
|
|
if (!desc.is_live()) {
|
|
return out << format("{{free {:d}}}", desc.dead_size());
|
|
} else {
|
|
auto m = desc.migrator();
|
|
auto x = reinterpret_cast<uintptr_t>(&desc) + sizeof(desc);
|
|
x = align_up(x, m->align());
|
|
auto obj = reinterpret_cast<const void*>(x);
|
|
return out << format("{{migrator={:p}, alignment={:d}, size={:d}}}",
|
|
(void*)m, m->align(), m->size(obj));
|
|
}
|
|
}
|
|
};
|
|
private:
|
|
region* _region = nullptr;
|
|
region_group* _group = nullptr;
|
|
segment* _active = nullptr;
|
|
size_t _active_offset;
|
|
segment_descriptor_hist _segment_descs; // Contains only closed segments
|
|
occupancy_stats _closed_occupancy;
|
|
occupancy_stats _non_lsa_occupancy;
|
|
// This helps us keeping track of the region_group* heap. That's because we call update before
|
|
// we have a chance to update the occupancy stats - mainly because at this point we don't know
|
|
// what will we do with the new segment. Also, because we are not ever interested in the
|
|
// fraction used, we'll keep it as a scalar and convert when we need to present it as an
|
|
// occupancy. We could actually just present this as a scalar as well and never use occupancies,
|
|
// but consistency is good.
|
|
size_t _evictable_space = 0;
|
|
// This is a mask applied to _evictable_space with bitwise-and before it's returned from evictable_space().
|
|
// Used for forcing the result to zero without using conditionals.
|
|
size_t _evictable_space_mask = std::numeric_limits<size_t>::max();
|
|
bool _evictable = false;
|
|
region_sanitizer _sanitizer;
|
|
uint64_t _id;
|
|
eviction_fn _eviction_fn;
|
|
|
|
region_group::region_heap::handle_type _heap_handle;
|
|
private:
|
|
struct compaction_lock {
|
|
region_impl& _region;
|
|
bool _prev;
|
|
compaction_lock(region_impl& r)
|
|
: _region(r)
|
|
, _prev(r._reclaiming_enabled)
|
|
{
|
|
_region._reclaiming_enabled = false;
|
|
}
|
|
~compaction_lock() {
|
|
_region._reclaiming_enabled = _prev;
|
|
}
|
|
};
|
|
|
|
void* alloc_small(const object_descriptor& desc, segment::size_type size, size_t alignment) {
|
|
if (!_active) {
|
|
_active = new_segment();
|
|
_active_offset = 0;
|
|
}
|
|
|
|
auto desc_encoded_size = desc.encoded_size();
|
|
|
|
size_t obj_offset = align_up_for_asan(align_up(_active_offset + desc_encoded_size, alignment));
|
|
if (obj_offset + size > segment::size) {
|
|
close_and_open();
|
|
return alloc_small(desc, size, alignment);
|
|
}
|
|
|
|
auto old_active_offset = _active_offset;
|
|
auto pos = _active->at<char>(_active_offset);
|
|
// Use non-canonical encoding to allow for alignment pad
|
|
desc.encode(pos, obj_offset - _active_offset);
|
|
unpoison(pos, size);
|
|
_active_offset = obj_offset + size;
|
|
|
|
// Align the end of the value so that the next descriptor is aligned
|
|
_active_offset = align_up_for_asan(_active_offset);
|
|
_active->record_alloc(_active_offset - old_active_offset);
|
|
return pos;
|
|
}
|
|
|
|
template<typename Func>
|
|
void for_each_live(segment* seg, Func&& func) {
|
|
// scylla-gdb.py:scylla_lsa_segment is coupled with this implementation.
|
|
|
|
static_assert(std::is_same<void, std::result_of_t<Func(const object_descriptor*, void*, size_t)>>::value, "bad Func signature");
|
|
|
|
auto pos = align_up_for_asan(seg->at<const char>(0));
|
|
while (pos < seg->at<const char>(segment::size)) {
|
|
auto old_pos = pos;
|
|
const auto desc = object_descriptor::decode_forwards(pos);
|
|
if (desc.is_live()) {
|
|
auto size = desc.live_size(pos);
|
|
func(&desc, const_cast<char*>(pos), size);
|
|
pos += size;
|
|
} else {
|
|
pos = old_pos + desc.dead_size();
|
|
}
|
|
pos = align_up_for_asan(pos);
|
|
}
|
|
}
|
|
|
|
void close_active() {
|
|
if (!_active) {
|
|
return;
|
|
}
|
|
if (_active_offset < segment::size) {
|
|
auto desc = object_descriptor::make_dead(segment::size - _active_offset);
|
|
auto pos =_active->at<char>(_active_offset);
|
|
desc.encode(pos);
|
|
}
|
|
llogger.trace("Closing segment {}, used={}, waste={} [B]", fmt::ptr(_active), _active->occupancy(), segment::size - _active_offset);
|
|
_closed_occupancy += _active->occupancy();
|
|
|
|
_segment_descs.push(shard_segment_pool.descriptor(_active));
|
|
_active = nullptr;
|
|
}
|
|
|
|
void free_segment(segment_descriptor& desc) noexcept {
|
|
free_segment(shard_segment_pool.segment_from(desc), desc);
|
|
}
|
|
|
|
void free_segment(segment* seg) noexcept {
|
|
free_segment(seg, shard_segment_pool.descriptor(seg));
|
|
}
|
|
|
|
void free_segment(segment* seg, segment_descriptor& desc) noexcept {
|
|
shard_segment_pool.free_segment(seg, desc);
|
|
if (_group) {
|
|
_evictable_space -= segment_size;
|
|
_group->decrease_usage(_heap_handle, -segment::size);
|
|
}
|
|
}
|
|
|
|
segment* new_segment() {
|
|
segment* seg = shard_segment_pool.new_segment(this);
|
|
if (_group) {
|
|
_evictable_space += segment_size;
|
|
_group->increase_usage(_heap_handle, segment::size);
|
|
}
|
|
return seg;
|
|
}
|
|
|
|
void compact_segment_locked(segment* seg, segment_descriptor& desc) {
|
|
auto seg_occupancy = desc.occupancy();
|
|
llogger.debug("Compacting segment {} from region {}, {}", fmt::ptr(seg), id(), seg_occupancy);
|
|
|
|
++_invalidate_counter;
|
|
|
|
for_each_live(seg, [this] (const object_descriptor* desc, void* obj, size_t size) {
|
|
auto dst = alloc_small(*desc, size, desc->alignment());
|
|
_sanitizer.on_migrate(obj, size, dst);
|
|
desc->migrator()->migrate(obj, dst, size);
|
|
});
|
|
|
|
free_segment(seg, desc);
|
|
shard_segment_pool.on_segment_compaction(seg_occupancy.used_space());
|
|
}
|
|
|
|
void close_and_open() {
|
|
segment* new_active = new_segment();
|
|
close_active();
|
|
_active = new_active;
|
|
_active_offset = 0;
|
|
}
|
|
|
|
static uint64_t next_id() {
|
|
static std::atomic<uint64_t> id{0};
|
|
return id.fetch_add(1);
|
|
}
|
|
struct degroup_temporarily {
|
|
region_impl* impl;
|
|
region_group* group;
|
|
explicit degroup_temporarily(region_impl* impl)
|
|
: impl(impl), group(impl->_group) {
|
|
if (group) {
|
|
group->del(impl);
|
|
}
|
|
}
|
|
~degroup_temporarily() {
|
|
if (group) {
|
|
group->add(impl);
|
|
}
|
|
}
|
|
};
|
|
|
|
public:
|
|
explicit region_impl(region* region, region_group* group = nullptr)
|
|
: _region(region), _group(group), _id(next_id())
|
|
{
|
|
_preferred_max_contiguous_allocation = max_managed_object_size;
|
|
tracker_instance._impl->register_region(this);
|
|
try {
|
|
if (group) {
|
|
group->add(this);
|
|
}
|
|
} catch (...) {
|
|
tracker_instance._impl->unregister_region(this);
|
|
throw;
|
|
}
|
|
}
|
|
|
|
virtual ~region_impl() {
|
|
_sanitizer.on_region_destruction();
|
|
|
|
tracker_instance._impl->unregister_region(this);
|
|
|
|
while (!_segment_descs.empty()) {
|
|
auto& desc = _segment_descs.one_of_largest();
|
|
_segment_descs.pop_one_of_largest();
|
|
assert(desc.is_empty());
|
|
free_segment(desc);
|
|
}
|
|
_closed_occupancy = {};
|
|
if (_active) {
|
|
assert(_active->is_empty());
|
|
free_segment(_active);
|
|
_active = nullptr;
|
|
}
|
|
if (_group) {
|
|
_group->del(this);
|
|
}
|
|
}
|
|
|
|
region_impl(region_impl&&) = delete;
|
|
region_impl(const region_impl&) = delete;
|
|
|
|
bool empty() const {
|
|
return occupancy().used_space() == 0;
|
|
}
|
|
|
|
occupancy_stats occupancy() const {
|
|
occupancy_stats total = _non_lsa_occupancy;
|
|
total += _closed_occupancy;
|
|
if (_active) {
|
|
total += _active->occupancy();
|
|
}
|
|
return total;
|
|
}
|
|
|
|
region_group* group() {
|
|
return _group;
|
|
}
|
|
|
|
occupancy_stats compactible_occupancy() const {
|
|
return _closed_occupancy;
|
|
}
|
|
|
|
occupancy_stats evictable_occupancy() const {
|
|
return occupancy_stats(0, _evictable_space & _evictable_space_mask);
|
|
}
|
|
|
|
void ground_evictable_occupancy() {
|
|
_evictable_space_mask = 0;
|
|
if (_group) {
|
|
_group->decrease_evictable_usage(_heap_handle);
|
|
}
|
|
}
|
|
|
|
//
|
|
// Returns true if this region can be compacted and compact() will make forward progress,
|
|
// so that this will eventually stop:
|
|
//
|
|
// while (is_compactible()) { compact(); }
|
|
//
|
|
bool is_compactible() const {
|
|
return _reclaiming_enabled
|
|
&& (_closed_occupancy.free_space() >= 2 * segment::size)
|
|
&& _segment_descs.contains_above_min();
|
|
}
|
|
|
|
bool is_idle_compactible() {
|
|
return is_compactible();
|
|
}
|
|
|
|
virtual void* alloc(allocation_strategy::migrate_fn migrator, size_t size, size_t alignment) override {
|
|
compaction_lock _(*this);
|
|
memory::on_alloc_point();
|
|
shard_segment_pool.on_memory_allocation(size);
|
|
if (size > max_managed_object_size) {
|
|
auto ptr = standard_allocator().alloc(migrator, size, alignment);
|
|
// This isn't very acurrate, the correct free_space value would be
|
|
// malloc_usable_size(ptr) - size, but there is no way to get
|
|
// the exact object size at free.
|
|
auto allocated_size = malloc_usable_size(ptr);
|
|
_non_lsa_occupancy += occupancy_stats(0, allocated_size);
|
|
if (_group) {
|
|
_evictable_space += allocated_size;
|
|
_group->increase_usage(_heap_handle, allocated_size);
|
|
}
|
|
shard_segment_pool.update_non_lsa_memory_in_use(allocated_size);
|
|
return ptr;
|
|
} else {
|
|
auto ptr = alloc_small(object_descriptor(migrator), (segment::size_type) size, alignment);
|
|
_sanitizer.on_allocation(ptr, size);
|
|
return ptr;
|
|
}
|
|
}
|
|
|
|
private:
|
|
void on_non_lsa_free(void* obj) noexcept {
|
|
auto allocated_size = malloc_usable_size(obj);
|
|
_non_lsa_occupancy -= occupancy_stats(0, allocated_size);
|
|
if (_group) {
|
|
_evictable_space -= allocated_size;
|
|
_group->decrease_usage(_heap_handle, allocated_size);
|
|
}
|
|
shard_segment_pool.update_non_lsa_memory_in_use(-allocated_size);
|
|
}
|
|
public:
|
|
virtual void free(void* obj) noexcept override {
|
|
compaction_lock _(*this);
|
|
segment* seg = shard_segment_pool.containing_segment(obj);
|
|
if (!seg) {
|
|
on_non_lsa_free(obj);
|
|
standard_allocator().free(obj);
|
|
return;
|
|
}
|
|
|
|
auto pos = reinterpret_cast<const char*>(obj);
|
|
auto desc = object_descriptor::decode_backwards(pos);
|
|
free(obj, desc.live_size(obj));
|
|
}
|
|
|
|
virtual void free(void* obj, size_t size) noexcept override {
|
|
compaction_lock _(*this);
|
|
segment* seg = shard_segment_pool.containing_segment(obj);
|
|
|
|
if (!seg) {
|
|
on_non_lsa_free(obj);
|
|
standard_allocator().free(obj, size);
|
|
return;
|
|
}
|
|
|
|
_sanitizer.on_free(obj, size);
|
|
|
|
segment_descriptor& seg_desc = shard_segment_pool.descriptor(seg);
|
|
|
|
auto pos = reinterpret_cast<const char*>(obj);
|
|
auto old_pos = pos;
|
|
auto desc = object_descriptor::decode_backwards(pos);
|
|
auto dead_size = align_up_for_asan(size + (old_pos - pos));
|
|
desc = object_descriptor::make_dead(dead_size);
|
|
auto npos = const_cast<char*>(pos);
|
|
desc.encode(npos);
|
|
poison(pos, dead_size);
|
|
|
|
if (seg != _active) {
|
|
_closed_occupancy -= seg->occupancy();
|
|
}
|
|
|
|
seg_desc.record_free(dead_size);
|
|
|
|
if (seg != _active) {
|
|
if (seg_desc.is_empty()) {
|
|
_segment_descs.erase(seg_desc);
|
|
free_segment(seg, seg_desc);
|
|
} else {
|
|
_segment_descs.adjust_up(seg_desc);
|
|
_closed_occupancy += seg_desc.occupancy();
|
|
}
|
|
}
|
|
}
|
|
|
|
virtual size_t object_memory_size_in_allocator(const void* obj) const noexcept override {
|
|
segment* seg = shard_segment_pool.containing_segment(obj);
|
|
|
|
if (!seg) {
|
|
return standard_allocator().object_memory_size_in_allocator(obj);
|
|
} else {
|
|
auto pos = reinterpret_cast<const char*>(obj);
|
|
auto desc = object_descriptor::decode_backwards(pos);
|
|
return desc.encoded_size() + desc.live_size(obj);
|
|
}
|
|
}
|
|
|
|
// Merges another region into this region. The other region is made
|
|
// to refer to this region.
|
|
// Doesn't invalidate references to allocated objects.
|
|
void merge(region_impl& other) noexcept {
|
|
// degroup_temporarily allocates via binomial_heap::push(), which should not
|
|
// fail, because we have a matching deallocation before that and we don't
|
|
// allocate between them.
|
|
memory::scoped_critical_alloc_section dfg;
|
|
|
|
compaction_lock dct1(*this);
|
|
compaction_lock dct2(other);
|
|
degroup_temporarily dgt1(this);
|
|
degroup_temporarily dgt2(&other);
|
|
|
|
if (_active && _active->is_empty()) {
|
|
shard_segment_pool.free_segment(_active);
|
|
_active = nullptr;
|
|
}
|
|
if (!_active) {
|
|
_active = other._active;
|
|
other._active = nullptr;
|
|
_active_offset = other._active_offset;
|
|
if (_active) {
|
|
shard_segment_pool.set_region(_active, this);
|
|
}
|
|
} else {
|
|
other.close_active();
|
|
}
|
|
|
|
for (auto& desc : other._segment_descs) {
|
|
shard_segment_pool.set_region(desc, this);
|
|
}
|
|
_segment_descs.merge(other._segment_descs);
|
|
|
|
_closed_occupancy += other._closed_occupancy;
|
|
_non_lsa_occupancy += other._non_lsa_occupancy;
|
|
other._closed_occupancy = {};
|
|
other._non_lsa_occupancy = {};
|
|
|
|
// Make sure both regions will notice a future increment
|
|
// to the reclaim counter
|
|
_invalidate_counter = std::max(_invalidate_counter, other._invalidate_counter);
|
|
|
|
_sanitizer.merge(other._sanitizer);
|
|
other._sanitizer = { };
|
|
}
|
|
|
|
// Returns occupancy of the sparsest compactible segment.
|
|
occupancy_stats min_occupancy() const {
|
|
if (_segment_descs.empty()) {
|
|
return {};
|
|
}
|
|
return _segment_descs.one_of_largest().occupancy();
|
|
}
|
|
|
|
// Compacts a single segment, most appropriate for it
|
|
void compact() {
|
|
compaction_lock _(*this);
|
|
auto& desc = _segment_descs.one_of_largest();
|
|
_segment_descs.pop_one_of_largest();
|
|
_closed_occupancy -= desc.occupancy();
|
|
segment* seg = shard_segment_pool.segment_from(desc);
|
|
compact_segment_locked(seg, desc);
|
|
}
|
|
|
|
// Compacts everything. Mainly for testing.
|
|
// Invalidates references to allocated objects.
|
|
void full_compaction() {
|
|
compaction_lock _(*this);
|
|
llogger.debug("Full compaction, {}", occupancy());
|
|
close_and_open();
|
|
segment_descriptor_hist all;
|
|
std::swap(all, _segment_descs);
|
|
_closed_occupancy = {};
|
|
while (!all.empty()) {
|
|
auto& desc = all.one_of_largest();
|
|
all.pop_one_of_largest();
|
|
compact_segment_locked(shard_segment_pool.segment_from(desc), desc);
|
|
}
|
|
llogger.debug("Done, {}", occupancy());
|
|
}
|
|
|
|
void compact_segment(segment* seg, segment_descriptor& desc) {
|
|
compaction_lock _(*this);
|
|
if (_active == seg) {
|
|
close_active();
|
|
}
|
|
_segment_descs.erase(desc);
|
|
_closed_occupancy -= desc.occupancy();
|
|
compact_segment_locked(seg, desc);
|
|
}
|
|
|
|
allocation_strategy& allocator() {
|
|
return *this;
|
|
}
|
|
|
|
uint64_t id() const {
|
|
return _id;
|
|
}
|
|
|
|
// Returns true if this pool is evictable, so that evict_some() can be called.
|
|
bool is_evictable() const {
|
|
return _evictable && _reclaiming_enabled;
|
|
}
|
|
|
|
memory::reclaiming_result evict_some() {
|
|
++_invalidate_counter;
|
|
return _eviction_fn();
|
|
}
|
|
|
|
void make_not_evictable() {
|
|
_evictable = false;
|
|
_eviction_fn = {};
|
|
}
|
|
|
|
void make_evictable(eviction_fn fn) {
|
|
_evictable = true;
|
|
_eviction_fn = std::move(fn);
|
|
}
|
|
|
|
const eviction_fn& evictor() const {
|
|
return _eviction_fn;
|
|
}
|
|
|
|
friend class region;
|
|
friend class region_group;
|
|
friend class region_group::region_evictable_occupancy_ascending_less_comparator;
|
|
};
|
|
|
|
inline void
|
|
region_group_binomial_group_sanity_check(const region_group::region_heap& bh) {
|
|
#ifdef SEASTAR_DEBUG
|
|
bool failed = false;
|
|
size_t last = std::numeric_limits<size_t>::max();
|
|
for (auto b = bh.ordered_begin(); b != bh.ordered_end(); b++) {
|
|
auto t = (*b)->evictable_occupancy().total_space();
|
|
if (!(t <= last)) {
|
|
failed = true;
|
|
break;
|
|
}
|
|
last = t;
|
|
}
|
|
if (!failed) {
|
|
return;
|
|
}
|
|
|
|
printf("Sanity checking FAILED, size %ld\n", bh.size());
|
|
for (auto b = bh.ordered_begin(); b != bh.ordered_end(); b++) {
|
|
auto r = (*b);
|
|
auto t = r->evictable_occupancy().total_space();
|
|
printf(" r = %p (id=%ld), occupancy = %ld\n",r, r->id(), t);
|
|
}
|
|
assert(0);
|
|
#endif
|
|
}
|
|
|
|
size_t tracker::reclamation_step() const {
|
|
return _impl->reclamation_step();
|
|
}
|
|
|
|
bool tracker::should_abort_on_bad_alloc() {
|
|
return _impl->should_abort_on_bad_alloc();
|
|
}
|
|
|
|
void tracker::configure(const config& cfg) {
|
|
if (cfg.defragment_on_idle) {
|
|
engine().set_idle_cpu_handler([this] (reactor::work_waiting_on_reactor check_for_work) {
|
|
return _impl->compact_on_idle(check_for_work);
|
|
});
|
|
}
|
|
|
|
_impl->set_reclamation_step(cfg.lsa_reclamation_step);
|
|
if (cfg.abort_on_lsa_bad_alloc) {
|
|
_impl->enable_abort_on_bad_alloc();
|
|
}
|
|
_impl->setup_background_reclaim(cfg.background_reclaim_sched_group);
|
|
}
|
|
|
|
memory::reclaiming_result tracker::reclaim(seastar::memory::reclaimer::request r) {
|
|
return reclaim(std::max(r.bytes_to_reclaim, _impl->reclamation_step() * segment::size))
|
|
? memory::reclaiming_result::reclaimed_something
|
|
: memory::reclaiming_result::reclaimed_nothing;
|
|
}
|
|
|
|
bool
|
|
region_group::region_evictable_occupancy_ascending_less_comparator::operator()(region_impl* r1, region_impl* r2) const {
|
|
return r1->evictable_occupancy().total_space() < r2->evictable_occupancy().total_space();
|
|
}
|
|
|
|
region::region()
|
|
: _impl(make_shared<impl>(this))
|
|
{ }
|
|
|
|
region::region(region_group& group)
|
|
: _impl(make_shared<impl>(this, &group)) {
|
|
}
|
|
|
|
region_impl& region::get_impl() {
|
|
return *static_cast<region_impl*>(_impl.get());
|
|
}
|
|
const region_impl& region::get_impl() const {
|
|
return *static_cast<const region_impl*>(_impl.get());
|
|
}
|
|
|
|
region::region(region&& other) {
|
|
this->_impl = std::move(other._impl);
|
|
get_impl()._region = this;
|
|
}
|
|
|
|
region& region::operator=(region&& other) {
|
|
this->_impl = std::move(other._impl);
|
|
get_impl()._region = this;
|
|
return *this;
|
|
}
|
|
|
|
region::~region() {
|
|
}
|
|
|
|
occupancy_stats region::occupancy() const {
|
|
return get_impl().occupancy();
|
|
}
|
|
|
|
region_group* region::group() {
|
|
return get_impl().group();
|
|
}
|
|
|
|
void region::merge(region& other) noexcept {
|
|
if (_impl != other._impl) {
|
|
get_impl().merge(other.get_impl());
|
|
other._impl = _impl;
|
|
}
|
|
}
|
|
|
|
void region::full_compaction() {
|
|
get_impl().full_compaction();
|
|
}
|
|
|
|
memory::reclaiming_result region::evict_some() {
|
|
if (get_impl().is_evictable()) {
|
|
return get_impl().evict_some();
|
|
}
|
|
return memory::reclaiming_result::reclaimed_nothing;
|
|
}
|
|
|
|
void region::make_evictable(eviction_fn fn) {
|
|
get_impl().make_evictable(std::move(fn));
|
|
}
|
|
|
|
void region::ground_evictable_occupancy() {
|
|
get_impl().ground_evictable_occupancy();
|
|
}
|
|
|
|
occupancy_stats region::evictable_occupancy() {
|
|
return get_impl().evictable_occupancy();
|
|
}
|
|
|
|
const eviction_fn& region::evictor() const {
|
|
return get_impl().evictor();
|
|
}
|
|
|
|
std::ostream& operator<<(std::ostream& out, const occupancy_stats& stats) {
|
|
return out << format("{:.2f}%, {:d} / {:d} [B]",
|
|
stats.used_fraction() * 100, stats.used_space(), stats.total_space());
|
|
}
|
|
|
|
occupancy_stats tracker::impl::region_occupancy() {
|
|
reclaiming_lock _(*this);
|
|
occupancy_stats total{};
|
|
for (auto&& r: _regions) {
|
|
total += r->occupancy();
|
|
}
|
|
return total;
|
|
}
|
|
|
|
occupancy_stats tracker::impl::occupancy() {
|
|
reclaiming_lock _(*this);
|
|
auto occ = region_occupancy();
|
|
{
|
|
auto s = shard_segment_pool.free_segments() * segment::size;
|
|
occ += occupancy_stats(s, s);
|
|
}
|
|
return occ;
|
|
}
|
|
|
|
size_t tracker::impl::non_lsa_used_space() {
|
|
#ifdef SEASTAR_DEFAULT_ALLOCATOR
|
|
return 0;
|
|
#else
|
|
auto free_space_in_lsa = shard_segment_pool.free_segments() * segment_size;
|
|
return memory::stats().allocated_memory() - region_occupancy().total_space() - free_space_in_lsa;
|
|
#endif
|
|
}
|
|
|
|
void tracker::impl::reclaim_all_free_segments()
|
|
{
|
|
llogger.debug("Reclaiming all free segments");
|
|
shard_segment_pool.reclaim_all_free_segments();
|
|
llogger.debug("Reclamation done");
|
|
}
|
|
|
|
void tracker::impl::full_compaction() {
|
|
reclaiming_lock _(*this);
|
|
|
|
llogger.debug("Full compaction on all regions, {}", region_occupancy());
|
|
|
|
for (region_impl* r : _regions) {
|
|
if (r->reclaiming_enabled()) {
|
|
r->full_compaction();
|
|
}
|
|
}
|
|
|
|
llogger.debug("Compaction done, {}", region_occupancy());
|
|
}
|
|
|
|
static void reclaim_from_evictable(region::impl& r, size_t target_mem_in_use, is_preemptible preempt) {
|
|
while (true) {
|
|
auto deficit = shard_segment_pool.total_memory_in_use() - target_mem_in_use;
|
|
auto occupancy = r.occupancy();
|
|
auto used = occupancy.used_space();
|
|
if (used == 0) {
|
|
break;
|
|
}
|
|
// Before attempting segment compaction, try to evict at least deficit and one segment more so that
|
|
// for workloads in which eviction order matches allocation order we will reclaim full segments
|
|
// without needing to perform expensive compaction.
|
|
auto used_target = used - std::min(used, deficit + segment::size);
|
|
llogger.debug("Evicting {} bytes from region {}, occupancy={}", used - used_target, r.id(), r.occupancy());
|
|
while (r.occupancy().used_space() > used_target || !r.is_compactible()) {
|
|
if (r.evict_some() == memory::reclaiming_result::reclaimed_nothing) {
|
|
if (r.is_compactible()) { // Need to make forward progress in case there is nothing to evict.
|
|
break;
|
|
}
|
|
llogger.debug("Unable to evict more, evicted {} bytes", used - r.occupancy().used_space());
|
|
return;
|
|
}
|
|
if (shard_segment_pool.total_memory_in_use() <= target_mem_in_use) {
|
|
llogger.debug("Target met after evicting {} bytes", used - r.occupancy().used_space());
|
|
return;
|
|
}
|
|
if (r.empty()) {
|
|
return;
|
|
}
|
|
if (preempt && need_preempt()) {
|
|
return;
|
|
}
|
|
}
|
|
llogger.debug("Compacting after evicting {} bytes", used - r.occupancy().used_space());
|
|
r.compact();
|
|
}
|
|
}
|
|
|
|
struct reclaim_timer {
|
|
clock::time_point start;
|
|
bool enabled;
|
|
reclaim_timer() {
|
|
if (timing_logger.is_enabled(logging::log_level::debug)) {
|
|
start = clock::now();
|
|
enabled = true;
|
|
} else {
|
|
enabled = false;
|
|
}
|
|
}
|
|
~reclaim_timer() {
|
|
if (enabled) {
|
|
auto duration = clock::now() - start;
|
|
timing_logger.debug("Reclamation cycle took {} us.",
|
|
std::chrono::duration_cast<std::chrono::duration<double, std::micro>>(duration).count());
|
|
}
|
|
}
|
|
void stop(size_t released) {
|
|
if (enabled) {
|
|
enabled = false;
|
|
auto duration = clock::now() - start;
|
|
auto bytes_per_second = static_cast<float>(released) / std::chrono::duration_cast<std::chrono::duration<float>>(duration).count();
|
|
timing_logger.debug("Reclamation cycle took {} us. Reclamation rate = {} MiB/s",
|
|
std::chrono::duration_cast<std::chrono::duration<double, std::micro>>(duration).count(),
|
|
format("{:.3f}", bytes_per_second / (1024*1024)));
|
|
}
|
|
}
|
|
};
|
|
|
|
idle_cpu_handler_result tracker::impl::compact_on_idle(work_waiting_on_reactor check_for_work) {
|
|
if (!_reclaiming_enabled) {
|
|
return idle_cpu_handler_result::no_more_work;
|
|
}
|
|
reclaiming_lock rl(*this);
|
|
if (_regions.empty()) {
|
|
return idle_cpu_handler_result::no_more_work;
|
|
}
|
|
segment_pool::reservation_goal open_emergency_pool(shard_segment_pool, 0);
|
|
|
|
auto cmp = [] (region::impl* c1, region::impl* c2) {
|
|
if (c1->is_idle_compactible() != c2->is_idle_compactible()) {
|
|
return !c1->is_idle_compactible();
|
|
}
|
|
return c2->min_occupancy() < c1->min_occupancy();
|
|
};
|
|
|
|
boost::range::make_heap(_regions, cmp);
|
|
|
|
while (!check_for_work()) {
|
|
boost::range::pop_heap(_regions, cmp);
|
|
region::impl* r = _regions.back();
|
|
|
|
if (!r->is_idle_compactible()) {
|
|
return idle_cpu_handler_result::no_more_work;
|
|
}
|
|
|
|
r->compact();
|
|
|
|
boost::range::push_heap(_regions, cmp);
|
|
}
|
|
return idle_cpu_handler_result::interrupted_by_higher_priority_task;
|
|
}
|
|
|
|
size_t tracker::impl::reclaim(size_t memory_to_release, is_preemptible preempt) {
|
|
// Reclamation steps:
|
|
// 1. Try to release free segments from segment pool and emergency reserve.
|
|
// 2. Compact used segments and/or evict data.
|
|
|
|
if (!_reclaiming_enabled) {
|
|
return 0;
|
|
}
|
|
reclaiming_lock rl(*this);
|
|
reclaim_timer timing_guard;
|
|
|
|
constexpr auto max_bytes = std::numeric_limits<size_t>::max() - segment::size;
|
|
auto segments_to_release = align_up(std::min(max_bytes, memory_to_release), segment::size) >> segment::size_shift;
|
|
auto nr_released = shard_segment_pool.reclaim_segments(segments_to_release, preempt);
|
|
size_t mem_released = nr_released * segment::size;
|
|
if (mem_released >= memory_to_release) {
|
|
return memory_to_release;
|
|
}
|
|
if (preempt && need_preempt()) {
|
|
return mem_released;
|
|
}
|
|
|
|
auto compacted = compact_and_evict_locked(shard_segment_pool.current_emergency_reserve_goal(), memory_to_release - mem_released, preempt);
|
|
|
|
if (compacted == 0) {
|
|
return mem_released;
|
|
}
|
|
|
|
// compact_and_evict_locked() will not return segments to the standard allocator,
|
|
// so do it here:
|
|
nr_released = shard_segment_pool.reclaim_segments(compacted / segment::size, preempt);
|
|
|
|
return mem_released + nr_released * segment::size;
|
|
}
|
|
|
|
size_t tracker::impl::compact_and_evict(size_t reserve_segments, size_t memory_to_release, is_preemptible preempt) {
|
|
if (!_reclaiming_enabled) {
|
|
return 0;
|
|
}
|
|
reclaiming_lock rl(*this);
|
|
reclaim_timer timing_guard;
|
|
size_t released = compact_and_evict_locked(reserve_segments, memory_to_release, preempt);
|
|
timing_guard.stop(released);
|
|
return released;
|
|
}
|
|
|
|
size_t tracker::impl::compact_and_evict_locked(size_t reserve_segments, size_t memory_to_release, is_preemptible preempt) {
|
|
//
|
|
// Algorithm outline.
|
|
//
|
|
// Regions are kept in a max-heap ordered so that regions with
|
|
// sparser segments are picked first. Non-compactible regions will be
|
|
// picked last. In each iteration we try to release one whole segment from
|
|
// the region which has the sparsest segment. We do it until we released
|
|
// enough segments or there are no more regions we can compact.
|
|
//
|
|
// When compaction is not sufficient to reclaim space, we evict data from
|
|
// evictable regions.
|
|
//
|
|
|
|
// This may run synchronously with allocation, so we should not allocate
|
|
// memory, otherwise we may get std::bad_alloc. Currently we only allocate
|
|
// in the logger when debug level is enabled. It's disabled during normal
|
|
// operation. Having it is still valuable during testing and in most cases
|
|
// should work just fine even if allocates.
|
|
|
|
size_t mem_released = 0;
|
|
|
|
size_t mem_in_use = shard_segment_pool.total_memory_in_use();
|
|
memory_to_release += (reserve_segments - std::min(reserve_segments, shard_segment_pool.free_segments())) * segment::size;
|
|
auto target_mem = mem_in_use - std::min(mem_in_use, memory_to_release - mem_released);
|
|
|
|
llogger.debug("Compacting, requested {} bytes, {} bytes in use, target is {}",
|
|
memory_to_release, mem_in_use, target_mem);
|
|
|
|
// Allow dipping into reserves while compacting
|
|
segment_pool::reservation_goal open_emergency_pool(shard_segment_pool, 0);
|
|
|
|
auto cmp = [] (region::impl* c1, region::impl* c2) {
|
|
if (c1->is_compactible() != c2->is_compactible()) {
|
|
return !c1->is_compactible();
|
|
}
|
|
return c2->min_occupancy() < c1->min_occupancy();
|
|
};
|
|
|
|
boost::range::make_heap(_regions, cmp);
|
|
|
|
if (llogger.is_enabled(logging::log_level::debug)) {
|
|
llogger.debug("Occupancy of regions:");
|
|
for (region::impl* r : _regions) {
|
|
llogger.debug(" - {}: min={}, avg={}", r->id(), r->min_occupancy(), r->compactible_occupancy());
|
|
}
|
|
}
|
|
|
|
while (shard_segment_pool.total_memory_in_use() > target_mem) {
|
|
boost::range::pop_heap(_regions, cmp);
|
|
region::impl* r = _regions.back();
|
|
|
|
if (!r->is_compactible()) {
|
|
llogger.trace("Unable to release segments, no compactible pools.");
|
|
break;
|
|
}
|
|
|
|
// Prefer evicting if average occupancy ratio is above the compaction threshold to avoid
|
|
// overhead of compaction in workloads where allocation order matches eviction order, where
|
|
// we can reclaim memory by eviction only. In some cases the cost of compaction on allocation
|
|
// would be higher than the cost of repopulating the region with evicted items.
|
|
if (r->is_evictable() && r->occupancy().used_space() >= max_used_space_ratio_for_compaction * r->occupancy().total_space()) {
|
|
reclaim_from_evictable(*r, target_mem, preempt);
|
|
} else {
|
|
r->compact();
|
|
}
|
|
|
|
boost::range::push_heap(_regions, cmp);
|
|
|
|
if (preempt && need_preempt()) {
|
|
break;
|
|
}
|
|
}
|
|
|
|
auto released_during_compaction = mem_in_use - shard_segment_pool.total_memory_in_use();
|
|
|
|
if (shard_segment_pool.total_memory_in_use() > target_mem) {
|
|
llogger.debug("Considering evictable regions.");
|
|
// FIXME: Fair eviction
|
|
for (region::impl* r : _regions) {
|
|
if (preempt && need_preempt()) {
|
|
break;
|
|
}
|
|
if (r->is_evictable()) {
|
|
reclaim_from_evictable(*r, target_mem, preempt);
|
|
if (shard_segment_pool.total_memory_in_use() <= target_mem) {
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
mem_released += mem_in_use - shard_segment_pool.total_memory_in_use();
|
|
|
|
llogger.debug("Released {} bytes (wanted {}), {} during compaction",
|
|
mem_released, memory_to_release, released_during_compaction);
|
|
|
|
return mem_released;
|
|
}
|
|
|
|
void tracker::impl::register_region(region::impl* r) {
|
|
// If needed, increase capacity of regions before taking the reclaim lock,
|
|
// to avoid failing an allocation when push_back() tries to increase
|
|
// capacity.
|
|
//
|
|
// The capacity increase is atomic (wrt _regions) so it cannot be
|
|
// observed
|
|
if (_regions.size() == _regions.capacity()) {
|
|
auto copy = _regions;
|
|
copy.reserve(copy.capacity() * 2);
|
|
_regions = std::move(copy);
|
|
}
|
|
reclaiming_lock _(*this);
|
|
_regions.push_back(r);
|
|
llogger.debug("Registered region @{} with id={}", fmt::ptr(r), r->id());
|
|
}
|
|
|
|
void tracker::impl::unregister_region(region::impl* r) noexcept {
|
|
reclaiming_lock _(*this);
|
|
llogger.debug("Unregistering region, id={}", r->id());
|
|
_regions.erase(std::remove(_regions.begin(), _regions.end(), r), _regions.end());
|
|
}
|
|
|
|
tracker::impl::impl() {
|
|
namespace sm = seastar::metrics;
|
|
|
|
_metrics.add_group("lsa", {
|
|
sm::make_gauge("total_space_bytes", [this] { return region_occupancy().total_space(); },
|
|
sm::description("Holds a current size of allocated memory in bytes.")),
|
|
|
|
sm::make_gauge("used_space_bytes", [this] { return region_occupancy().used_space(); },
|
|
sm::description("Holds a current amount of used memory in bytes.")),
|
|
|
|
sm::make_gauge("small_objects_total_space_bytes", [this] { return region_occupancy().total_space() - shard_segment_pool.non_lsa_memory_in_use(); },
|
|
sm::description("Holds a current size of \"small objects\" memory region in bytes.")),
|
|
|
|
sm::make_gauge("small_objects_used_space_bytes", [this] { return region_occupancy().used_space() - shard_segment_pool.non_lsa_memory_in_use(); },
|
|
sm::description("Holds a current amount of used \"small objects\" memory in bytes.")),
|
|
|
|
sm::make_gauge("large_objects_total_space_bytes", [this] { return shard_segment_pool.non_lsa_memory_in_use(); },
|
|
sm::description("Holds a current size of allocated non-LSA memory.")),
|
|
|
|
sm::make_gauge("non_lsa_used_space_bytes", [this] { return non_lsa_used_space(); },
|
|
sm::description("Holds a current amount of used non-LSA memory.")),
|
|
|
|
sm::make_gauge("free_space", [this] { return shard_segment_pool.unreserved_free_segments() * segment_size; },
|
|
sm::description("Holds a current amount of free memory that is under lsa control.")),
|
|
|
|
sm::make_gauge("occupancy", [this] { return region_occupancy().used_fraction() * 100; },
|
|
sm::description("Holds a current portion (in percents) of the used memory.")),
|
|
|
|
sm::make_derive("segments_compacted", [this] { return shard_segment_pool.statistics().segments_compacted; },
|
|
sm::description("Counts a number of compacted segments.")),
|
|
|
|
sm::make_derive("memory_compacted", [this] { return shard_segment_pool.statistics().memory_compacted; },
|
|
sm::description("Counts number of bytes which were copied as part of segment compaction.")),
|
|
|
|
sm::make_derive("memory_allocated", [this] { return shard_segment_pool.statistics().memory_allocated; },
|
|
sm::description("Counts number of bytes which were requested from LSA allocator.")),
|
|
});
|
|
}
|
|
|
|
tracker::impl::~impl() {
|
|
if (!_regions.empty()) {
|
|
for (auto&& r : _regions) {
|
|
llogger.error("Region with id={} not unregistered!", r->id());
|
|
}
|
|
abort();
|
|
}
|
|
}
|
|
|
|
bool segment_pool::compact_segment(segment* seg) {
|
|
auto& desc = descriptor(seg);
|
|
if (!desc._region->reclaiming_enabled()) {
|
|
return false;
|
|
}
|
|
|
|
// Called with emergency reserve, open one for
|
|
// region::alloc_small not to throw if it needs
|
|
// one more segment
|
|
reservation_goal open_emergency_pool(*this, 0);
|
|
allocation_lock no_alloc(*this);
|
|
tracker_reclaimer_lock no_reclaim;
|
|
|
|
desc._region->compact_segment(seg, desc);
|
|
return true;
|
|
}
|
|
|
|
region_group_reclaimer region_group::no_reclaimer;
|
|
|
|
uint64_t region_group::top_region_evictable_space() const {
|
|
return _regions.empty() ? 0 : _regions.top()->evictable_occupancy().total_space();
|
|
}
|
|
|
|
region* region_group::get_largest_region() {
|
|
if (!_maximal_rg || _maximal_rg->_regions.empty()) {
|
|
return nullptr;
|
|
}
|
|
return _maximal_rg->_regions.top()->_region;
|
|
}
|
|
|
|
void
|
|
region_group::add(region_group* child) {
|
|
child->_subgroup_heap_handle = _subgroups.push(child);
|
|
update(child->_total_memory);
|
|
}
|
|
|
|
void
|
|
region_group::del(region_group* child) {
|
|
_subgroups.erase(child->_subgroup_heap_handle);
|
|
update(-child->_total_memory);
|
|
}
|
|
|
|
void
|
|
region_group::add(region_impl* child) {
|
|
child->_heap_handle = _regions.push(child);
|
|
region_group_binomial_group_sanity_check(_regions);
|
|
update(child->occupancy().total_space());
|
|
}
|
|
|
|
void
|
|
region_group::del(region_impl* child) {
|
|
_regions.erase(child->_heap_handle);
|
|
region_group_binomial_group_sanity_check(_regions);
|
|
update(-child->occupancy().total_space());
|
|
}
|
|
|
|
bool
|
|
region_group::execution_permitted() noexcept {
|
|
return do_for_each_parent(this, [] (auto rg) {
|
|
return rg->under_pressure() ? stop_iteration::yes : stop_iteration::no;
|
|
}) == nullptr;
|
|
}
|
|
|
|
future<>
|
|
region_group::start_releaser(scheduling_group deferred_work_sg) {
|
|
return with_scheduling_group(deferred_work_sg, [this] {
|
|
return later().then([this] {
|
|
return repeat([this] () noexcept {
|
|
if (_shutdown_requested) {
|
|
return make_ready_future<stop_iteration>(stop_iteration::yes);
|
|
}
|
|
|
|
if (!_blocked_requests.empty() && execution_permitted()) {
|
|
auto req = std::move(_blocked_requests.front());
|
|
_blocked_requests.pop_front();
|
|
req->allocate();
|
|
return make_ready_future<stop_iteration>(stop_iteration::no);
|
|
} else {
|
|
// Block reclaiming to prevent signal() from being called by reclaimer inside wait()
|
|
// FIXME: handle allocation failures (not very likely) like allocating_section does
|
|
tracker_reclaimer_lock rl;
|
|
return _relief.wait().then([] {
|
|
return stop_iteration::no;
|
|
});
|
|
}
|
|
});
|
|
});
|
|
});
|
|
}
|
|
|
|
region_group::region_group(sstring name, region_group *parent,
|
|
region_group_reclaimer& reclaimer, scheduling_group deferred_work_sg)
|
|
: _parent(parent)
|
|
, _reclaimer(reclaimer)
|
|
, _blocked_requests(on_request_expiry{std::move(name)})
|
|
, _releaser(reclaimer_can_block() ? start_releaser(deferred_work_sg) : make_ready_future<>())
|
|
{
|
|
if (_parent) {
|
|
_parent->add(this);
|
|
}
|
|
}
|
|
|
|
bool region_group::reclaimer_can_block() const {
|
|
return _reclaimer.throttle_threshold() != std::numeric_limits<size_t>::max();
|
|
}
|
|
|
|
void region_group::notify_relief() {
|
|
_relief.signal();
|
|
for (region_group* child : _subgroups) {
|
|
child->notify_relief();
|
|
}
|
|
}
|
|
|
|
void region_group::update(ssize_t delta) {
|
|
// Most-enclosing group which was relieved.
|
|
region_group* top_relief = nullptr;
|
|
|
|
do_for_each_parent(this, [&top_relief, delta] (region_group* rg) mutable {
|
|
rg->update_maximal_rg();
|
|
rg->_total_memory += delta;
|
|
|
|
if (rg->_total_memory >= rg->_reclaimer.soft_limit_threshold()) {
|
|
rg->_reclaimer.notify_soft_pressure();
|
|
} else {
|
|
rg->_reclaimer.notify_soft_relief();
|
|
}
|
|
|
|
if (rg->_total_memory > rg->_reclaimer.throttle_threshold()) {
|
|
rg->_reclaimer.notify_pressure();
|
|
} else if (rg->_reclaimer.under_pressure()) {
|
|
rg->_reclaimer.notify_relief();
|
|
top_relief = rg;
|
|
}
|
|
|
|
return stop_iteration::no;
|
|
});
|
|
|
|
if (top_relief) {
|
|
top_relief->notify_relief();
|
|
}
|
|
}
|
|
|
|
allocating_section::guard::guard()
|
|
: _prev(shard_segment_pool.emergency_reserve_max())
|
|
{ }
|
|
|
|
allocating_section::guard::~guard() {
|
|
shard_segment_pool.set_emergency_reserve_max(_prev);
|
|
}
|
|
|
|
void allocating_section::maybe_decay_reserve() {
|
|
// The decay rate is inversely proportional to the reserve
|
|
// (every (s_segments_per_decay/_lsa_reserve) allocations).
|
|
//
|
|
// If the reserve is high, it is expensive since we may need to
|
|
// evict a lot of memory to satisfy the reserve. Hence, we are
|
|
// willing to risk a more frequent bad_alloc in order to decay it.
|
|
// The cost of a bad_alloc is also lower compared to maintaining
|
|
// the reserve.
|
|
//
|
|
// If the reserve is low, it is not expensive to maintain, so we
|
|
// decay it at a lower rate.
|
|
|
|
_remaining_lsa_segments_until_decay -= _lsa_reserve;
|
|
if (_remaining_lsa_segments_until_decay < 0) {
|
|
_remaining_lsa_segments_until_decay = s_segments_per_decay;
|
|
_lsa_reserve = std::max(s_min_lsa_reserve, _lsa_reserve / 2);
|
|
llogger.debug("Decaying LSA reserve in section {} to {} segments", static_cast<void*>(this), _lsa_reserve);
|
|
}
|
|
|
|
_remaining_std_bytes_until_decay -= _std_reserve;
|
|
if (_remaining_std_bytes_until_decay < 0) {
|
|
_remaining_std_bytes_until_decay = s_bytes_per_decay;
|
|
_std_reserve = std::max(s_min_std_reserve, _std_reserve / 2);
|
|
llogger.debug("Decaying standard allocator head-room in section {} to {} [B]", static_cast<void*>(this), _std_reserve);
|
|
}
|
|
}
|
|
|
|
void allocating_section::reserve() {
|
|
try {
|
|
shard_segment_pool.set_emergency_reserve_max(std::max(_lsa_reserve, _minimum_lsa_emergency_reserve));
|
|
shard_segment_pool.refill_emergency_reserve();
|
|
|
|
while (true) {
|
|
size_t free = memory::stats().free_memory();
|
|
if (free >= _std_reserve) {
|
|
break;
|
|
}
|
|
if (!tracker_instance.reclaim(_std_reserve - free)) {
|
|
throw std::bad_alloc();
|
|
}
|
|
}
|
|
|
|
shard_segment_pool.clear_allocation_failure_flag();
|
|
} catch (const std::bad_alloc&) {
|
|
if (shard_tracker().should_abort_on_bad_alloc()) {
|
|
llogger.error("Aborting due to allocation failure");
|
|
abort();
|
|
}
|
|
throw;
|
|
}
|
|
}
|
|
|
|
void allocating_section::on_alloc_failure(logalloc::region& r) {
|
|
r.allocator().invalidate_references();
|
|
if (shard_segment_pool.allocation_failure_flag()) {
|
|
_lsa_reserve *= 2;
|
|
llogger.debug("LSA allocation failure, increasing reserve in section {} to {} segments", fmt::ptr(this), _lsa_reserve);
|
|
} else {
|
|
_std_reserve *= 2;
|
|
llogger.debug("Standard allocator failure, increasing head-room in section {} to {} [B]", fmt::ptr(this), _std_reserve);
|
|
}
|
|
reserve();
|
|
}
|
|
|
|
void allocating_section::set_lsa_reserve(size_t reserve) {
|
|
_lsa_reserve = reserve;
|
|
}
|
|
|
|
void allocating_section::set_std_reserve(size_t reserve) {
|
|
_std_reserve = reserve;
|
|
}
|
|
|
|
void region_group::on_request_expiry::operator()(std::unique_ptr<allocating_function>& func) noexcept {
|
|
func->fail(std::make_exception_ptr(blocked_requests_timed_out_error{_name}));
|
|
}
|
|
|
|
future<> prime_segment_pool(size_t available_memory, size_t min_free_memory) {
|
|
return smp::invoke_on_all([=] {
|
|
shard_segment_pool.prime(available_memory, min_free_memory);
|
|
});
|
|
}
|
|
|
|
uint64_t memory_allocated() {
|
|
return shard_segment_pool.statistics().memory_allocated;
|
|
}
|
|
|
|
uint64_t memory_compacted() {
|
|
return shard_segment_pool.statistics().memory_compacted;
|
|
}
|
|
|
|
occupancy_stats lsa_global_occupancy_stats() {
|
|
return occupancy_stats(shard_segment_pool.total_free_memory(), shard_segment_pool.total_memory_in_use());
|
|
}
|
|
|
|
}
|
|
|
|
// Orders segments by free space, assuming all segments have the same size.
|
|
// This avoids using the occupancy, which entails extra division operations.
|
|
template<>
|
|
size_t hist_key<logalloc::segment_descriptor>(const logalloc::segment_descriptor& desc) {
|
|
return desc._free_space;
|
|
}
|