libspl: move taskq implementation from libzpool

Sponsored-by: https://despairlabs.com/sponsor/ Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Rob Norris <robn@despairlabs.com> Closes #17861
2026-05-22 02:27:36 +03:00 · 2025-10-27 09:08:01 +11:00
parent a2e10ebfd3
commit 3823492ca1
3 changed files with 1 additions and 1 deletions
@@ -25,6 +25,7 @@ libspl_la_SOURCES = \
 	%D%/rwlock.c \
 	%D%/strlcat.c \
 	%D%/strlcpy.c \
+	%D%/taskq.c \
 	%D%/thread.c \
 	%D%/timestamp.c \
 	%D%/tunables.c \
@@ -0,0 +1,417 @@
+// SPDX-License-Identifier: CDDL-1.0
+/*
+ * 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 https://opensource.org/licenses/CDDL-1.0.
+ * 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 2010 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+/*
+ * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
+ * Copyright 2012 Garrett D'Amore <garrett@damore.org>.  All rights reserved.
+ * Copyright (c) 2014 by Delphix. All rights reserved.
+ */
+
+#include <sys/zfs_context.h>
+
+int taskq_now;
+taskq_t *system_taskq;
+taskq_t *system_delay_taskq;
+
+static pthread_key_t taskq_tsd;
+
+#define	TASKQ_ACTIVE	0x00010000
+
+static taskq_ent_t *
+task_alloc(taskq_t *tq, int tqflags)
+{
+	taskq_ent_t *t;
+	int rv;
+
+again:	if ((t = tq->tq_freelist) != NULL && tq->tq_nalloc >= tq->tq_minalloc) {
+		ASSERT(!(t->tqent_flags & TQENT_FLAG_PREALLOC));
+		tq->tq_freelist = t->tqent_next;
+	} else {
+		if (tq->tq_nalloc >= tq->tq_maxalloc) {
+			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. If we have tasks
+			 * complete before one second timeout expires then
+			 * taskq_ent_free will signal us and we will
+			 * immediately retry the allocation.
+			 */
+			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 (taskq_ent_t), tqflags);
+
+		mutex_enter(&tq->tq_lock);
+		if (t != NULL) {
+			/* Make sure we start without any flags */
+			t->tqent_flags = 0;
+			tq->tq_nalloc++;
+		}
+	}
+	return (t);
+}
+
+static void
+task_free(taskq_t *tq, taskq_ent_t *t)
+{
+	if (tq->tq_nalloc <= tq->tq_minalloc) {
+		t->tqent_next = tq->tq_freelist;
+		tq->tq_freelist = t;
+	} else {
+		tq->tq_nalloc--;
+		mutex_exit(&tq->tq_lock);
+		kmem_free(t, sizeof (taskq_ent_t));
+		mutex_enter(&tq->tq_lock);
+	}
+
+	if (tq->tq_maxalloc_wait)
+		cv_signal(&tq->tq_maxalloc_cv);
+}
+
+taskqid_t
+taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t tqflags)
+{
+	taskq_ent_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);
+	}
+	if (tqflags & TQ_FRONT) {
+		t->tqent_next = tq->tq_task.tqent_next;
+		t->tqent_prev = &tq->tq_task;
+	} else {
+		t->tqent_next = &tq->tq_task;
+		t->tqent_prev = tq->tq_task.tqent_prev;
+	}
+	t->tqent_next->tqent_prev = t;
+	t->tqent_prev->tqent_next = t;
+	t->tqent_func = func;
+	t->tqent_arg = arg;
+	t->tqent_flags = 0;
+	cv_signal(&tq->tq_dispatch_cv);
+	mutex_exit(&tq->tq_lock);
+	return (1);
+}
+
+taskqid_t
+taskq_dispatch_delay(taskq_t *tq, task_func_t func, void *arg, uint_t tqflags,
+    clock_t expire_time)
+{
+	(void) tq, (void) func, (void) arg, (void) tqflags, (void) expire_time;
+	return (0);
+}
+
+int
+taskq_empty_ent(taskq_ent_t *t)
+{
+	return (t->tqent_next == NULL);
+}
+
+void
+taskq_init_ent(taskq_ent_t *t)
+{
+	t->tqent_next = NULL;
+	t->tqent_prev = NULL;
+	t->tqent_func = NULL;
+	t->tqent_arg = NULL;
+	t->tqent_flags = 0;
+}
+
+void
+taskq_dispatch_ent(taskq_t *tq, task_func_t func, void *arg, uint_t flags,
+    taskq_ent_t *t)
+{
+	ASSERT(func != NULL);
+
+	/*
+	 * Mark it as a prealloc'd task.  This is important
+	 * to ensure that we don't free it later.
+	 */
+	t->tqent_flags |= TQENT_FLAG_PREALLOC;
+	/*
+	 * Enqueue the task to the underlying queue.
+	 */
+	mutex_enter(&tq->tq_lock);
+
+	if (flags & TQ_FRONT) {
+		t->tqent_next = tq->tq_task.tqent_next;
+		t->tqent_prev = &tq->tq_task;
+	} else {
+		t->tqent_next = &tq->tq_task;
+		t->tqent_prev = tq->tq_task.tqent_prev;
+	}
+	t->tqent_next->tqent_prev = t;
+	t->tqent_prev->tqent_next = t;
+	t->tqent_func = func;
+	t->tqent_arg = arg;
+	cv_signal(&tq->tq_dispatch_cv);
+	mutex_exit(&tq->tq_lock);
+}
+
+void
+taskq_wait(taskq_t *tq)
+{
+	mutex_enter(&tq->tq_lock);
+	while (tq->tq_task.tqent_next != &tq->tq_task || tq->tq_active != 0)
+		cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
+	mutex_exit(&tq->tq_lock);
+}
+
+void
+taskq_wait_id(taskq_t *tq, taskqid_t id)
+{
+	(void) id;
+	taskq_wait(tq);
+}
+
+void
+taskq_wait_outstanding(taskq_t *tq, taskqid_t id)
+{
+	(void) id;
+	taskq_wait(tq);
+}
+
+static __attribute__((noreturn)) void
+taskq_thread(void *arg)
+{
+	taskq_t *tq = arg;
+	taskq_ent_t *t;
+	boolean_t prealloc;
+
+	VERIFY0(pthread_setspecific(taskq_tsd, tq));
+
+	mutex_enter(&tq->tq_lock);
+	while (tq->tq_flags & TASKQ_ACTIVE) {
+		if ((t = tq->tq_task.tqent_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->tqent_prev->tqent_next = t->tqent_next;
+		t->tqent_next->tqent_prev = t->tqent_prev;
+		t->tqent_next = NULL;
+		t->tqent_prev = NULL;
+		prealloc = t->tqent_flags & TQENT_FLAG_PREALLOC;
+		mutex_exit(&tq->tq_lock);
+
+		rw_enter(&tq->tq_threadlock, RW_READER);
+		t->tqent_func(t->tqent_arg);
+		rw_exit(&tq->tq_threadlock);
+
+		mutex_enter(&tq->tq_lock);
+		if (!prealloc)
+			task_free(tq, t);
+	}
+	tq->tq_nthreads--;
+	cv_broadcast(&tq->tq_wait_cv);
+	mutex_exit(&tq->tq_lock);
+	thread_exit();
+}
+
+taskq_t *
+taskq_create(const char *name, int nthreads, pri_t pri,
+    int minalloc, int maxalloc, uint_t flags)
+{
+	(void) pri;
+	taskq_t *tq = kmem_zalloc(sizeof (taskq_t), KM_SLEEP);
+	int t;
+
+	if (flags & TASKQ_THREADS_CPU_PCT) {
+		int pct;
+		ASSERT3S(nthreads, >=, 0);
+		ASSERT3S(nthreads, <=, 100);
+		pct = MIN(nthreads, 100);
+		pct = MAX(pct, 0);
+
+		nthreads = (sysconf(_SC_NPROCESSORS_ONLN) * pct) / 100;
+		nthreads = MAX(nthreads, 1);	/* need at least 1 thread */
+	} else {
+		ASSERT3S(nthreads, >=, 1);
+	}
+
+	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);
+	cv_init(&tq->tq_maxalloc_cv, NULL, CV_DEFAULT, NULL);
+	(void) strlcpy(tq->tq_name, name, sizeof (tq->tq_name));
+	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.tqent_next = &tq->tq_task;
+	tq->tq_task.tqent_prev = &tq->tq_task;
+	tq->tq_threadlist = kmem_alloc(nthreads * sizeof (kthread_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++)
+		VERIFY((tq->tq_threadlist[t] = thread_create_named(tq->tq_name,
+		    NULL, 0, taskq_thread, tq, 0, &p0, TS_RUN, pri)) != NULL);
+
+	return (tq);
+}
+
+void
+taskq_destroy(taskq_t *tq)
+{
+	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);
+		taskq_ent_t *tqent_nexttq = tq->tq_freelist->tqent_next;
+		task_free(tq, tq->tq_freelist);
+		tq->tq_freelist = tqent_nexttq;
+	}
+
+	mutex_exit(&tq->tq_lock);
+
+	kmem_free(tq->tq_threadlist, nthreads * sizeof (kthread_t *));
+
+	rw_destroy(&tq->tq_threadlock);
+	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));
+}
+
+/*
+ * Create a taskq with a specified number of pool threads. Allocate
+ * and return an array of nthreads kthread_t pointers, one for each
+ * thread in the pool. The array is not ordered and must be freed
+ * by the caller.
+ */
+taskq_t *
+taskq_create_synced(const char *name, int nthreads, pri_t pri,
+    int minalloc, int maxalloc, uint_t flags, kthread_t ***ktpp)
+{
+	taskq_t *tq;
+	kthread_t **kthreads = kmem_zalloc(sizeof (*kthreads) * nthreads,
+	    KM_SLEEP);
+
+	(void) pri; (void) minalloc; (void) maxalloc;
+
+	flags &= ~(TASKQ_DYNAMIC | TASKQ_THREADS_CPU_PCT | TASKQ_DC_BATCH);
+
+	tq = taskq_create(name, nthreads, minclsyspri, nthreads, INT_MAX,
+	    flags | TASKQ_PREPOPULATE);
+	VERIFY(tq != NULL);
+	VERIFY(tq->tq_nthreads == nthreads);
+
+	for (int i = 0; i < nthreads; i++) {
+		kthreads[i] = tq->tq_threadlist[i];
+	}
+	*ktpp = kthreads;
+	return (tq);
+}
+
+int
+taskq_member(taskq_t *tq, kthread_t *t)
+{
+	int i;
+
+	if (taskq_now)
+		return (1);
+
+	for (i = 0; i < tq->tq_nthreads; i++)
+		if (tq->tq_threadlist[i] == t)
+			return (1);
+
+	return (0);
+}
+
+taskq_t *
+taskq_of_curthread(void)
+{
+	return (pthread_getspecific(taskq_tsd));
+}
+
+int
+taskq_cancel_id(taskq_t *tq, taskqid_t id)
+{
+	(void) tq, (void) id;
+	return (ENOENT);
+}
+
+void
+system_taskq_init(void)
+{
+	VERIFY0(pthread_key_create(&taskq_tsd, NULL));
+	system_taskq = taskq_create("system_taskq", 64, maxclsyspri, 4, 512,
+	    TASKQ_DYNAMIC | TASKQ_PREPOPULATE);
+	system_delay_taskq = taskq_create("delay_taskq", 4, maxclsyspri, 4,
+	    512, TASKQ_DYNAMIC | TASKQ_PREPOPULATE);
+}
+
+void
+system_taskq_fini(void)
+{
+	taskq_destroy(system_taskq);
+	system_taskq = NULL; /* defensive */
+	taskq_destroy(system_delay_taskq);
+	system_delay_taskq = NULL;
+	VERIFY0(pthread_key_delete(taskq_tsd));
+}