Update core ZFS code from build 121 to build 141.

[zfs.git] / lib / libzpool / taskq.c

diff --git a/lib/libzpool/taskq.c b/lib/libzpool/taskq.c
index 1a73fe8..8db5d11 100644 (file)
--- a/lib/libzpool/taskq.c
+++ b/lib/libzpool/taskq.c
@@ -19,7 +19,7 @@
  * CDDL HEADER END
  */
 /*
- * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
+ * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
 
@@ -49,6 +49,8 @@ struct taskq {
        int             tq_nalloc;
        int             tq_minalloc;
        int             tq_maxalloc;
+       kcondvar_t      tq_maxalloc_cv;
+       int             tq_maxalloc_wait;
        task_t          *tq_freelist;
        task_t          tq_task;
 };
@@ -57,26 +59,36 @@ static task_t *
 task_alloc(taskq_t *tq, int tqflags)
 {
        task_t *t;
+       int rv;
 
-       if ((t = tq->tq_freelist) != NULL && tq->tq_nalloc >= tq->tq_minalloc) {
+again: if ((t = tq->tq_freelist) != NULL && tq->tq_nalloc >= tq->tq_minalloc) {
                tq->tq_freelist = t->task_next;
        } else {
-               mutex_exit(&tq->tq_lock);
                if (tq->tq_nalloc >= tq->tq_maxalloc) {
-                       if (!(tqflags & KM_SLEEP)) {
-                               mutex_enter(&tq->tq_lock);
+                       if (!(tqflags & KM_SLEEP))
                                return (NULL);
-                       }
+
                        /*
                         * We don't want to exceed tq_maxalloc, but we can't
                         * wait for other tasks to complete (and thus free up
                         * task structures) without risking deadlock with
                         * the caller.  So, we just delay for one second
-                        * to throttle the allocation rate.
+                        * to throttle the allocation rate. If we have tasks
+                        * complete before one second timeout expires then
+                        * taskq_ent_free will signal us and we will
+                        * immediately retry the allocation.
                         */
-                       delay(hz);
+                       tq->tq_maxalloc_wait++;
+                       rv = cv_timedwait(&tq->tq_maxalloc_cv,
+                           &tq->tq_lock, ddi_get_lbolt() + hz);
+                       tq->tq_maxalloc_wait--;
+                       if (rv > 0)
+                               goto again;             /* signaled */
                }
+               mutex_exit(&tq->tq_lock);
+
                t = kmem_alloc(sizeof (task_t), tqflags);
+
                mutex_enter(&tq->tq_lock);
                if (t != NULL)
                        tq->tq_nalloc++;
@@ -96,6 +108,9 @@ task_free(taskq_t *tq, task_t *t)
                kmem_free(t, sizeof (task_t));
                mutex_enter(&tq->tq_lock);
        }
+
+       if (tq->tq_maxalloc_wait)
+               cv_signal(&tq->tq_maxalloc_cv);
 }
 
 taskqid_t
@@ -114,8 +129,13 @@ taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t tqflags)
                mutex_exit(&tq->tq_lock);
                return (0);
        }
-       t->task_next = &tq->tq_task;
-       t->task_prev = tq->tq_task.task_prev;
+       if (tqflags & TQ_FRONT) {
+               t->task_next = tq->tq_task.task_next;
+               t->task_prev = &tq->tq_task;
+       } else {
+               t->task_next = &tq->tq_task;
+               t->task_prev = tq->tq_task.task_prev;
+       }
        t->task_next->task_prev = t;
        t->task_prev->task_next = t;
        t->task_func = func;
@@ -191,6 +211,7 @@ taskq_create(const char *name, int nthreads, pri_t pri,
        mutex_init(&tq->tq_lock, NULL, MUTEX_DEFAULT, NULL);
        cv_init(&tq->tq_dispatch_cv, NULL, CV_DEFAULT, NULL);
        cv_init(&tq->tq_wait_cv, NULL, CV_DEFAULT, NULL);
+       cv_init(&tq->tq_maxalloc_cv, NULL, CV_DEFAULT, NULL);
        tq->tq_flags = flags | TASKQ_ACTIVE;
        tq->tq_active = nthreads;
        tq->tq_nthreads = nthreads;
@@ -247,6 +268,7 @@ taskq_destroy(taskq_t *tq)
        mutex_destroy(&tq->tq_lock);
        cv_destroy(&tq->tq_dispatch_cv);
        cv_destroy(&tq->tq_wait_cv);
+       cv_destroy(&tq->tq_maxalloc_cv);
 
        kmem_free(tq, sizeof (taskq_t));
 }
@@ -272,3 +294,10 @@ system_taskq_init(void)
        system_taskq = taskq_create("system_taskq", 64, minclsyspri, 4, 512,
            TASKQ_DYNAMIC | TASKQ_PREPOPULATE);
 }
+
+void
+system_taskq_fini(void)
+{
+       taskq_destroy(system_taskq);
+       system_taskq = NULL; /* defensive */
+}