/*
* 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.
*/
#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;
kcondvar_t tq_maxalloc_cv;
int tq_maxalloc_wait;
task_t *tq_freelist;
task_t tq_task;
};
static task_t *
task_alloc(taskq_t *tq, int tqflags)
{
task_t *t;
int rv;
again: if ((t = tq->tq_freelist) != NULL && tq->tq_nalloc >= tq->tq_minalloc) {
tq->tq_freelist = t->task_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 (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);
}
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)
{
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);
}
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;
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;
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);
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);
cv_destroy(&tq->tq_maxalloc_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);
}
void
system_taskq_fini(void)
{
taskq_destroy(system_taskq);
system_taskq = NULL; /* defensive */
}