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[PATCH v2 1/3] thread-pool: optimize scheduling of completion bottom hal
From: |
Paolo Bonzini |
Subject: |
[PATCH v2 1/3] thread-pool: optimize scheduling of completion bottom half |
Date: |
Thu, 12 May 2022 12:43:44 +0200 |
The completion bottom half was scheduled within the pool->lock
critical section. That actually results in worse performance,
because the worker thread can run its own small critical section
and go to sleep before the bottom half starts running.
Note that this simple change does not produce an improvement without
changing the thread pool QemuSemaphore to a condition variable.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
util/thread-pool.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/util/thread-pool.c b/util/thread-pool.c
index 196835b4d3..4979f30ca3 100644
--- a/util/thread-pool.c
+++ b/util/thread-pool.c
@@ -127,9 +127,8 @@ static void *worker_thread(void *opaque)
smp_wmb();
req->state = THREAD_DONE;
- qemu_mutex_lock(&pool->lock);
-
qemu_bh_schedule(pool->completion_bh);
+ qemu_mutex_lock(&pool->lock);
}
pool->cur_threads--;
--
2.36.0