diff options
| author | Peter Lieven <pl@kamp.de> | 2017-03-16 17:02:49 +0100 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2017-03-17 12:54:21 +0100 |
| commit | b7a745dc33a18377bb4a8dfe54d1df01ea60bf66 (patch) | |
| tree | 9c74188a1a049f02e91512244913b85f7930df7f /util | |
| parent | 8cd1a3e470212685bdd48ac03fdf9721dafc100b (diff) | |
thread-pool: add missing qemu_bh_cancel in completion function
commit 3c80ca15 fixed a deadlock scenarion with nested aio_poll invocations.
However, the rescheduling of the completion BH introcuded unnecessary spinning
in the main-loop. On very fast file backends this can even lead to the
"WARNING: I/O thread spun for 1000 iterations" message popping up.
Callgrind reports about 3-4% less instructions with this patch running
qemu-img bench on a ramdisk based VMDK file.
Fixes: 3c80ca158c96ff902a30883a8933e755988948b1
Cc: qemu-stable@nongnu.org
Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'util')
| -rw-r--r-- | util/thread-pool.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/util/thread-pool.c b/util/thread-pool.c index ce6cd30193..610646d131 100644 --- a/util/thread-pool.c +++ b/util/thread-pool.c @@ -188,6 +188,13 @@ restart: aio_context_release(pool->ctx); elem->common.cb(elem->common.opaque, elem->ret); aio_context_acquire(pool->ctx); + + /* We can safely cancel the completion_bh here regardless of someone + * else having scheduled it meanwhile because we reenter the + * completion function anyway (goto restart). + */ + qemu_bh_cancel(pool->completion_bh); + qemu_aio_unref(elem); goto restart; } else { |