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logalloc: report increases of reserves

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The log-structured allocator maintains memory reserves to so that
operations using log-strucutured allocator memory can have some
working memory and can allocate. The reserves start small and are
increased if allocation failures are encountered. Before starting
an operation, the allocator first frees memory to satisfy the reserves.

One problem is that if the reserves are set to a high value and
we encounter a stall, then, first, we have no idea what value
the reserves are set to, and second, we have no idea what operation
caused the reserves to be increased.

We fix this problem by promoting the log reports of reserve increases
from DEBUG level to INFO level and by attaching a stack trace to
those reports. This isn't optimal since the messages are used
for debugging, not for informing the user about anything important
for the operation of the node, but I see no other way to obtain
the information.

Ref #13930.

Closes scylladb/scylladb#15153
This commit is contained in:
Avi Kivity
2023-08-24 12:37:02 +03:00
committed by Tomasz Grabiec
parent 4af585ec0e
commit ee9cc450d4
1 changed files with 2 additions and 2 deletions
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4
utils/logalloc.cc
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@@ -2924,10 +2924,10 @@ void allocating_section::on_alloc_failure(logalloc::region& r) {
r.allocator().invalidate_references();
if (r.get_tracker().get_impl().segment_pool().allocation_failure_flag()) {
_lsa_reserve *= 2;
llogger.debug("LSA allocation failure, increasing reserve in section {} to {} segments", fmt::ptr(this), _lsa_reserve);
llogger.info("LSA allocation failure, increasing reserve in section {} to {} segments; trace: {}", fmt::ptr(this), _lsa_reserve, current_backtrace());
} else {
_std_reserve *= 2;
llogger.debug("Standard allocator failure, increasing head-room in section {} to {} [B]", fmt::ptr(this), _std_reserve);
llogger.info("Standard allocator failure, increasing head-room in section {} to {} [B]; trace: {}", fmt::ptr(this), _std_reserve, current_backtrace());
}
reserve(r.get_tracker().get_impl());
}