zfs-builds-mm/zfs-0.8.0/lib/libzpool/taskq.c

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2019-07-06 23:40:11 +02:00
/*
* 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 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;
#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)
{
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)
{
taskq_wait(tq);
}
void
taskq_wait_outstanding(taskq_t *tq, taskqid_t id)
{
taskq_wait(tq);
}
static void
taskq_thread(void *arg)
{
taskq_t *tq = arg;
taskq_ent_t *t;
boolean_t prealloc;
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();
}
/*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;
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) strncpy(tq->tq_name, name, TASKQ_NAMELEN);
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(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);
task_free(tq, task_alloc(tq, KM_SLEEP));
}
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));
}
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);
}
int
taskq_cancel_id(taskq_t *tq, taskqid_t id)
{
return (ENOENT);
}
void
system_taskq_init(void)
{
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;
}