Date: Fri, 28 May 2010 18:15:34 +0000 (UTC) From: Zachary Loafman <zml@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r208624 - head/sys/kern Message-ID: <201005281815.o4SIFYY4070355@svn.freebsd.org>
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Author: zml Date: Fri May 28 18:15:34 2010 New Revision: 208624 URL: http://svn.freebsd.org/changeset/base/208624 Log: Avoid a wakeup(9) if we can be sure no one is waiting on the task. Submitted by: Matthew Fleming <matthew.fleming@isilon.com> Reviewed by: zml, jhb Modified: head/sys/kern/subr_taskqueue.c Modified: head/sys/kern/subr_taskqueue.c ============================================================================== --- head/sys/kern/subr_taskqueue.c Fri May 28 18:15:28 2010 (r208623) +++ head/sys/kern/subr_taskqueue.c Fri May 28 18:15:34 2010 (r208624) @@ -57,6 +57,7 @@ struct taskqueue { int tq_spin; int tq_flags; int tq_tasks_running; + int tq_task_waiters; }; #define TQ_FLAGS_ACTIVE (1 << 0) @@ -240,7 +241,8 @@ taskqueue_run(struct taskqueue *queue) TQ_LOCK(queue); queue->tq_tasks_running--; - wakeup(task); + if (queue->tq_task_waiters > 0) + wakeup(task); } /* @@ -256,15 +258,21 @@ taskqueue_drain(struct taskqueue *queue, { if (queue->tq_spin) { /* XXX */ mtx_lock_spin(&queue->tq_mutex); - while (task->ta_pending != 0 || queue->tq_tasks_running > 0) + while (task->ta_pending != 0 || queue->tq_tasks_running > 0) { + queue->tq_task_waiters++; msleep_spin(task, &queue->tq_mutex, "-", 0); + queue->tq_task_waiters--; + } mtx_unlock_spin(&queue->tq_mutex); } else { WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__); mtx_lock(&queue->tq_mutex); - while (task->ta_pending != 0 || queue->tq_tasks_running > 0) + while (task->ta_pending != 0 || queue->tq_tasks_running > 0) { + queue->tq_task_waiters++; msleep(task, &queue->tq_mutex, PWAIT, "-", 0); + queue->tq_task_waiters--; + } mtx_unlock(&queue->tq_mutex); } }
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