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Revert "virtio: Lazy interrupts"

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This reverts commit 817023f91741e43731823e72d60800016cbf2633; causes hangs
and throughput problems.
This commit is contained in:
Avi Kivity
2014-11-24 09:28:41 +02:00
parent 1238807d98
commit 88b38bfbdf
1 changed files with 7 additions and 22 deletions
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29
net/virtio.cc
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@@ -206,12 +206,11 @@ private:
used _used;
std::atomic<uint16_t>* _avail_event;
std::atomic<uint16_t>* _used_event;
uint16_t _used_event_last_set = 0;
semaphore _available_descriptors = { 0 };
int _free_head = -1;
int _free_last = -1;
bool _lazy_interrupts = false;
public:
explicit vring(config conf);
void set_notifier(std::unique_ptr<virtio_notifier> notifier) {
_notifier = std::move(notifier);
@@ -239,9 +238,6 @@ public:
void post(Iterator begin, Iterator end);
semaphore& available_descriptors() { return _available_descriptors; }
void set_lazy_interrupts() { _lazy_interrupts = true; }
void do_complete();
private:
// Let host know about interrupt delivery
void disable_interrupts() {
@@ -256,14 +252,7 @@ private:
if (!_config.event_index) {
_avail._shared->_flags.store(0, std::memory_order_relaxed);
} else {
auto used_event = tail;
if (_lazy_interrupts) {
used_event = uint16_t(tail + uint16_t(size() / 4));
}
if (used_event != _used_event_last_set) {
_used_event_last_set = used_event;
_used_event->store(used_event, std::memory_order_relaxed);
}
_used_event->store(tail, std::memory_order_relaxed);
}
// We need to set the host notification flag then check if the queue is
@@ -302,6 +291,7 @@ private:
}
}
void do_complete();
size_t mask() { return size() - 1; }
size_t masked(size_t idx) { return idx & mask(); }
size_t available();
@@ -505,9 +495,8 @@ public:
};
virtio_net_device::txq::txq(virtio_net_device& dev, vring::config config)
: _dev(dev) , _ring(config) {
_ring.set_lazy_interrupts();
virtio_net_device::txq::txq(virtio_net_device& dev, vring::config config)
: _dev(dev), _ring(config) {
}
future<>
@@ -553,10 +542,6 @@ virtio_net_device::txq::post(packet p) {
std::move(p));
auto nr_frags = q.nr_frags();
if (_ring.available_descriptors().current() < nr_frags) {
_ring.do_complete();
}
return _ring.available_descriptors().wait(nr_frags).then([this, nr_frags, p = std::move(q)] () mutable {
static auto fragment_to_buffer = [this] (fragment f) {
vring::buffer b;
@@ -584,8 +569,8 @@ virtio_net_device::txq::post(packet p) {
});
}
virtio_net_device::rxq::rxq(virtio_net_device& dev, vring::config config)
: _dev(dev), _ring(config) {
virtio_net_device::rxq::rxq(virtio_net_device& dev, vring::config config)
: _dev(dev), _ring(config) {
}
future<>