From 75ada6b7631bdf5d9f56af845c5096f5d75d33bf Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Tue, 15 Jul 2014 16:44:25 +0200 Subject: thread-pool: avoid per-thread-pool EventNotifier EventNotifier is implemented using an eventfd or pipe. It therefore consumes file descriptors, which can be limited by rlimits and should therefore be used sparingly. Switch from EventNotifier to QEMUBH in thread-pool.c. Originally EventNotifier was used because qemu_bh_schedule() was not thread-safe yet. Reported-by: Christian Borntraeger Signed-off-by: Stefan Hajnoczi (cherry picked from commit c2e50e3d11a0bf4c973cc30478c1af0f2d5f8e81) Signed-off-by: Michael Roth --- thread-pool.c | 21 ++++++++------------- 1 file changed, 8 insertions(+), 13 deletions(-) diff --git a/thread-pool.c b/thread-pool.c index dfb699dd94..4cfd07893f 100644 --- a/thread-pool.c +++ b/thread-pool.c @@ -21,7 +21,6 @@ #include "block/coroutine.h" #include "trace.h" #include "block/block_int.h" -#include "qemu/event_notifier.h" #include "block/thread-pool.h" #include "qemu/main-loop.h" @@ -57,8 +56,8 @@ struct ThreadPoolElement { }; struct ThreadPool { - EventNotifier notifier; AioContext *ctx; + QEMUBH *completion_bh; QemuMutex lock; QemuCond check_cancel; QemuCond worker_stopped; @@ -119,7 +118,7 @@ static void *worker_thread(void *opaque) qemu_cond_broadcast(&pool->check_cancel); } - event_notifier_set(&pool->notifier); + qemu_bh_schedule(pool->completion_bh); } pool->cur_threads--; @@ -168,12 +167,11 @@ static void spawn_thread(ThreadPool *pool) } } -static void event_notifier_ready(EventNotifier *notifier) +static void thread_pool_completion_bh(void *opaque) { - ThreadPool *pool = container_of(notifier, ThreadPool, notifier); + ThreadPool *pool = opaque; ThreadPoolElement *elem, *next; - event_notifier_test_and_clear(notifier); restart: QLIST_FOREACH_SAFE(elem, &pool->head, all, next) { if (elem->state != THREAD_CANCELED && elem->state != THREAD_DONE) { @@ -215,7 +213,7 @@ static void thread_pool_cancel(BlockDriverAIOCB *acb) qemu_sem_timedwait(&pool->sem, 0) == 0) { QTAILQ_REMOVE(&pool->request_list, elem, reqs); elem->state = THREAD_CANCELED; - event_notifier_set(&pool->notifier); + qemu_bh_schedule(pool->completion_bh); } else { pool->pending_cancellations++; while (elem->state != THREAD_CANCELED && elem->state != THREAD_DONE) { @@ -224,7 +222,7 @@ static void thread_pool_cancel(BlockDriverAIOCB *acb) pool->pending_cancellations--; } qemu_mutex_unlock(&pool->lock); - event_notifier_ready(&pool->notifier); + thread_pool_completion_bh(pool); } static const AIOCBInfo thread_pool_aiocb_info = { @@ -293,8 +291,8 @@ static void thread_pool_init_one(ThreadPool *pool, AioContext *ctx) } memset(pool, 0, sizeof(*pool)); - event_notifier_init(&pool->notifier, false); pool->ctx = ctx; + pool->completion_bh = aio_bh_new(ctx, thread_pool_completion_bh, pool); qemu_mutex_init(&pool->lock); qemu_cond_init(&pool->check_cancel); qemu_cond_init(&pool->worker_stopped); @@ -304,8 +302,6 @@ static void thread_pool_init_one(ThreadPool *pool, AioContext *ctx) QLIST_INIT(&pool->head); QTAILQ_INIT(&pool->request_list); - - aio_set_event_notifier(ctx, &pool->notifier, event_notifier_ready); } ThreadPool *thread_pool_new(AioContext *ctx) @@ -339,11 +335,10 @@ void thread_pool_free(ThreadPool *pool) qemu_mutex_unlock(&pool->lock); - aio_set_event_notifier(pool->ctx, &pool->notifier, NULL); + qemu_bh_delete(pool->completion_bh); qemu_sem_destroy(&pool->sem); qemu_cond_destroy(&pool->check_cancel); qemu_cond_destroy(&pool->worker_stopped); qemu_mutex_destroy(&pool->lock); - event_notifier_cleanup(&pool->notifier); g_free(pool); } -- cgit v1.2.1