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authorStefan Hajnoczi <stefanha@redhat.com>2014-07-15 16:44:25 +0200
committerKevin Wolf <kwolf@redhat.com>2014-08-15 15:07:14 +0200
commitc2e50e3d11a0bf4c973cc30478c1af0f2d5f8e81 (patch)
tree1a825a1c605343e093dde7b3db50530fa25518cf /thread-pool.c
parent2a87151fb2725658f7419038a80f91065159f34b (diff)
downloadqemu-arm-c2e50e3d11a0bf4c973cc30478c1af0f2d5f8e81.tar.gz
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 <borntraeger@de.ibm.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'thread-pool.c')
-rw-r--r--thread-pool.c21
1 files 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);
}