diff mbox

[24/25] thread-pool: avoid per-thread-pool EventNotifier

Message ID 1409160982-16389-25-git-send-email-mdroth@linux.vnet.ibm.com
State New
Headers show

Commit Message

Michael Roth Aug. 27, 2014, 5:36 p.m. UTC 
From: Stefan Hajnoczi <stefanha@redhat.com>

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>
(cherry picked from commit c2e50e3d11a0bf4c973cc30478c1af0f2d5f8e81)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
---
 thread-pool.c | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)
diff mbox

Patch

diff --git a/thread-pool.c b/thread-pool.c
index dfb699d..4cfd078 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);
 }