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-rw-r--r--zfs/lib/libzpool/taskq.c261
1 files changed, 261 insertions, 0 deletions
diff --git a/zfs/lib/libzpool/taskq.c b/zfs/lib/libzpool/taskq.c
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+++ b/zfs/lib/libzpool/taskq.c
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+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright 2008 Sun Microsystems, Inc. All rights reserved.
+ * Use is subject to license terms.
+ */
+
+#include <sys/zfs_context.h>
+
+int taskq_now;
+taskq_t *system_taskq;
+
+typedef struct task {
+ struct task *task_next;
+ struct task *task_prev;
+ task_func_t *task_func;
+ void *task_arg;
+} task_t;
+
+#define TASKQ_ACTIVE 0x00010000
+
+struct taskq {
+ kmutex_t tq_lock;
+ krwlock_t tq_threadlock;
+ kcondvar_t tq_dispatch_cv;
+ kcondvar_t tq_wait_cv;
+ thread_t *tq_threadlist;
+ int tq_flags;
+ int tq_active;
+ int tq_nthreads;
+ int tq_nalloc;
+ int tq_minalloc;
+ int tq_maxalloc;
+ task_t *tq_freelist;
+ task_t tq_task;
+};
+
+static task_t *
+task_alloc(taskq_t *tq, int tqflags)
+{
+ task_t *t;
+
+ 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);
+ 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.
+ */
+ delay(hz);
+ }
+ t = kmem_alloc(sizeof (task_t), tqflags);
+ mutex_enter(&tq->tq_lock);
+ if (t != NULL)
+ tq->tq_nalloc++;
+ }
+ return (t);
+}
+
+static void
+task_free(taskq_t *tq, task_t *t)
+{
+ if (tq->tq_nalloc <= tq->tq_minalloc) {
+ t->task_next = tq->tq_freelist;
+ tq->tq_freelist = t;
+ } else {
+ tq->tq_nalloc--;
+ mutex_exit(&tq->tq_lock);
+ kmem_free(t, sizeof (task_t));
+ mutex_enter(&tq->tq_lock);
+ }
+}
+
+taskqid_t
+taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t tqflags)
+{
+ task_t *t;
+
+ if (taskq_now) {
+ func(arg);
+ return (1);
+ }
+
+ mutex_enter(&tq->tq_lock);
+ ASSERT(tq->tq_flags & TASKQ_ACTIVE);
+ if ((t = task_alloc(tq, tqflags)) == NULL) {
+ mutex_exit(&tq->tq_lock);
+ return (0);
+ }
+ 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;
+ t->task_arg = arg;
+ cv_signal(&tq->tq_dispatch_cv);
+ mutex_exit(&tq->tq_lock);
+ return (1);
+}
+
+void
+taskq_wait(taskq_t *tq)
+{
+ mutex_enter(&tq->tq_lock);
+ while (tq->tq_task.task_next != &tq->tq_task || tq->tq_active != 0)
+ cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
+ mutex_exit(&tq->tq_lock);
+}
+
+static void *
+taskq_thread(void *arg)
+{
+ taskq_t *tq = arg;
+ task_t *t;
+
+ mutex_enter(&tq->tq_lock);
+ while (tq->tq_flags & TASKQ_ACTIVE) {
+ if ((t = tq->tq_task.task_next) == &tq->tq_task) {
+ if (--tq->tq_active == 0)
+ cv_broadcast(&tq->tq_wait_cv);
+ cv_wait(&tq->tq_dispatch_cv, &tq->tq_lock);
+ tq->tq_active++;
+ continue;
+ }
+ t->task_prev->task_next = t->task_next;
+ t->task_next->task_prev = t->task_prev;
+ mutex_exit(&tq->tq_lock);
+
+ rw_enter(&tq->tq_threadlock, RW_READER);
+ t->task_func(t->task_arg);
+ rw_exit(&tq->tq_threadlock);
+
+ mutex_enter(&tq->tq_lock);
+ task_free(tq, t);
+ }
+ tq->tq_nthreads--;
+ cv_broadcast(&tq->tq_wait_cv);
+ mutex_exit(&tq->tq_lock);
+ return (NULL);
+}
+
+/*ARGSUSED*/
+taskq_t *
+taskq_create(const char *name, int nthreads, pri_t pri,
+ int minalloc, int maxalloc, uint_t flags)
+{
+ taskq_t *tq = kmem_zalloc(sizeof (taskq_t), KM_SLEEP);
+ int t;
+
+ rw_init(&tq->tq_threadlock, NULL, RW_DEFAULT, NULL);
+ 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);
+ tq->tq_flags = flags | TASKQ_ACTIVE;
+ tq->tq_active = nthreads;
+ tq->tq_nthreads = nthreads;
+ tq->tq_minalloc = minalloc;
+ tq->tq_maxalloc = maxalloc;
+ tq->tq_task.task_next = &tq->tq_task;
+ tq->tq_task.task_prev = &tq->tq_task;
+ tq->tq_threadlist = kmem_alloc(nthreads * sizeof (thread_t), KM_SLEEP);
+
+ if (flags & TASKQ_PREPOPULATE) {
+ mutex_enter(&tq->tq_lock);
+ while (minalloc-- > 0)
+ task_free(tq, task_alloc(tq, KM_SLEEP));
+ mutex_exit(&tq->tq_lock);
+ }
+
+ for (t = 0; t < nthreads; t++)
+ (void) thr_create(0, 0, taskq_thread,
+ tq, THR_BOUND, &tq->tq_threadlist[t]);
+
+ return (tq);
+}
+
+void
+taskq_destroy(taskq_t *tq)
+{
+ int t;
+ int nthreads = tq->tq_nthreads;
+
+ taskq_wait(tq);
+
+ mutex_enter(&tq->tq_lock);
+
+ tq->tq_flags &= ~TASKQ_ACTIVE;
+ cv_broadcast(&tq->tq_dispatch_cv);
+
+ while (tq->tq_nthreads != 0)
+ cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
+
+ tq->tq_minalloc = 0;
+ while (tq->tq_nalloc != 0) {
+ ASSERT(tq->tq_freelist != NULL);
+ task_free(tq, task_alloc(tq, KM_SLEEP));
+ }
+
+ mutex_exit(&tq->tq_lock);
+
+ for (t = 0; t < nthreads; t++)
+ (void) thr_join(tq->tq_threadlist[t], NULL, NULL);
+
+ kmem_free(tq->tq_threadlist, nthreads * sizeof (thread_t));
+
+ rw_destroy(&tq->tq_threadlock);
+ mutex_destroy(&tq->tq_lock);
+ cv_destroy(&tq->tq_dispatch_cv);
+ cv_destroy(&tq->tq_wait_cv);
+
+ kmem_free(tq, sizeof (taskq_t));
+}
+
+int
+taskq_member(taskq_t *tq, void *t)
+{
+ int i;
+
+ if (taskq_now)
+ return (1);
+
+ for (i = 0; i < tq->tq_nthreads; i++)
+ if (tq->tq_threadlist[i] == (thread_t)(uintptr_t)t)
+ return (1);
+
+ return (0);
+}
+
+void
+system_taskq_init(void)
+{
+ system_taskq = taskq_create("system_taskq", 64, minclsyspri, 4, 512,
+ TASKQ_DYNAMIC | TASKQ_PREPOPULATE);
+}