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| author | Stefan Hajnoczi | 2016-12-01 20:26:51 +0100 |
|---|---|---|
| committer | Stefan Hajnoczi | 2017-01-03 17:38:50 +0100 |
| commit | 82a41186941c419afde977f477f19c545b40c1c5 (patch) | |
| tree | 32d517c6b4b6454814fd54af17bc0b5f7f0ed82c /trace-events | |
| parent | virtio: disable virtqueue notifications during polling (diff) | |
| download | qemu-82a41186941c419afde977f477f19c545b40c1c5.tar.gz qemu-82a41186941c419afde977f477f19c545b40c1c5.tar.xz qemu-82a41186941c419afde977f477f19c545b40c1c5.zip | |
aio: self-tune polling time
This patch is based on the algorithm for the kvm.ko halt_poll_ns
parameter in Linux. The initial polling time is zero.
If the event loop is woken up within the maximum polling time it means
polling could be effective, so grow polling time.
If the event loop is woken up beyond the maximum polling time it means
polling is not effective, so shrink polling time.
If the event loop makes progress within the current polling time then
the sweet spot has been reached.
This algorithm adjusts the polling time so it can adapt to variations in
workloads. The goal is to reach the sweet spot while also recognizing
when polling would hurt more than help.
Two new trace events, poll_grow and poll_shrink, are added for observing
polling time adjustment.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20161201192652.9509-13-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'trace-events')
| -rw-r--r-- | trace-events | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/trace-events b/trace-events index 7fe3a1b0e8..1181486454 100644 --- a/trace-events +++ b/trace-events @@ -28,6 +28,8 @@ # aio-posix.c run_poll_handlers_begin(void *ctx, int64_t max_ns) "ctx %p max_ns %"PRId64 run_poll_handlers_end(void *ctx, bool progress) "ctx %p progress %d" +poll_shrink(void *ctx, int64_t old, int64_t new) "ctx %p old %"PRId64" new %"PRId64 +poll_grow(void *ctx, int64_t old, int64_t new) "ctx %p old %"PRId64" new %"PRId64 # thread-pool.c thread_pool_submit(void *pool, void *req, void *opaque) "pool %p req %p opaque %p" |