module_param(spl_taskq_thread_bind, int, 0644);
MODULE_PARM_DESC(spl_taskq_thread_bind, "Bind taskq thread to CPU by default");
+
+int spl_taskq_thread_dynamic = 1;
+module_param(spl_taskq_thread_dynamic, int, 0644);
+MODULE_PARM_DESC(spl_taskq_thread_dynamic, "Allow dynamic taskq threads");
+
+int spl_taskq_thread_priority = 1;
+module_param(spl_taskq_thread_priority, int, 0644);
+MODULE_PARM_DESC(spl_taskq_thread_priority,
+ "Allow non-default priority for taskq threads");
+
+int spl_taskq_thread_sequential = 4;
+module_param(spl_taskq_thread_sequential, int, 0644);
+MODULE_PARM_DESC(spl_taskq_thread_sequential,
+ "Create new taskq threads after N sequential tasks");
+
/* Global system-wide dynamic task queue available for all consumers */
taskq_t *system_taskq;
EXPORT_SYMBOL(system_taskq);
+/* Private dedicated taskq for creating new taskq threads on demand. */
+static taskq_t *dynamic_taskq;
+static taskq_thread_t *taskq_thread_create(taskq_t *);
+
static int
task_km_flags(uint_t flags)
{
}
EXPORT_SYMBOL(taskq_wait);
-int
-taskq_member(taskq_t *tq, void *t)
+static int
+taskq_member_impl(taskq_t *tq, void *t)
{
struct list_head *l;
taskq_thread_t *tqt;
+ int found = 0;
ASSERT(tq);
ASSERT(t);
+ ASSERT(spin_is_locked(&tq->tq_lock));
list_for_each(l, &tq->tq_thread_list) {
tqt = list_entry(l, taskq_thread_t, tqt_thread_list);
- if (tqt->tqt_thread == (struct task_struct *)t)
- return (1);
+ if (tqt->tqt_thread == (struct task_struct *)t) {
+ found = 1;
+ break;
+ }
}
+ return (found);
+}
- return (0);
+int
+taskq_member(taskq_t *tq, void *t)
+{
+ int found;
+
+ spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
+ found = taskq_member_impl(tq, t);
+ spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
+
+ return (found);
}
EXPORT_SYMBOL(taskq_member);
}
EXPORT_SYMBOL(taskq_cancel_id);
+static int taskq_thread_spawn(taskq_t *tq);
+
taskqid_t
taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t flags)
{
spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
/* Taskq being destroyed and all tasks drained */
- if (!(tq->tq_flags & TQ_ACTIVE))
+ if (!(tq->tq_flags & TASKQ_ACTIVE))
goto out;
/* Do not queue the task unless there is idle thread for it */
wake_up(&tq->tq_work_waitq);
out:
+ /* Spawn additional taskq threads if required. */
+ if (tq->tq_nactive == tq->tq_nthreads)
+ (void) taskq_thread_spawn(tq);
+
spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
return (rc);
}
spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
/* Taskq being destroyed and all tasks drained */
- if (!(tq->tq_flags & TQ_ACTIVE))
+ if (!(tq->tq_flags & TASKQ_ACTIVE))
goto out;
if ((t = task_alloc(tq, flags)) == NULL)
spin_unlock(&t->tqent_lock);
out:
+ /* Spawn additional taskq threads if required. */
+ if (tq->tq_nactive == tq->tq_nthreads)
+ (void) taskq_thread_spawn(tq);
spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
return (rc);
}
{
ASSERT(tq);
ASSERT(func);
- ASSERT(!(tq->tq_flags & TASKQ_DYNAMIC));
spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
/* Taskq being destroyed and all tasks drained */
- if (!(tq->tq_flags & TQ_ACTIVE)) {
+ if (!(tq->tq_flags & TASKQ_ACTIVE)) {
t->tqent_id = 0;
goto out;
}
wake_up(&tq->tq_work_waitq);
out:
+ /* Spawn additional taskq threads if required. */
+ if (tq->tq_nactive == tq->tq_nthreads)
+ (void) taskq_thread_spawn(tq);
spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
}
EXPORT_SYMBOL(taskq_dispatch_ent);
}
EXPORT_SYMBOL(taskq_init_ent);
+/*
+ * Return the next pending task, preference is given to tasks on the
+ * priority list which were dispatched with TQ_FRONT.
+ */
+static taskq_ent_t *
+taskq_next_ent(taskq_t *tq)
+{
+ struct list_head *list;
+
+ ASSERT(spin_is_locked(&tq->tq_lock));
+
+ if (!list_empty(&tq->tq_prio_list))
+ list = &tq->tq_prio_list;
+ else if (!list_empty(&tq->tq_pend_list))
+ list = &tq->tq_pend_list;
+ else
+ return (NULL);
+
+ return (list_entry(list->next, taskq_ent_t, tqent_list));
+}
+
+/*
+ * Spawns a new thread for the specified taskq.
+ */
+static void
+taskq_thread_spawn_task(void *arg)
+{
+ taskq_t *tq = (taskq_t *)arg;
+
+ (void) taskq_thread_create(tq);
+
+ spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
+ tq->tq_nspawn--;
+ spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
+}
+
+/*
+ * Spawn addition threads for dynamic taskqs (TASKQ_DYNMAIC) the current
+ * number of threads is insufficient to handle the pending tasks. These
+ * new threads must be created by the dedicated dynamic_taskq to avoid
+ * deadlocks between thread creation and memory reclaim. The system_taskq
+ * which is also a dynamic taskq cannot be safely used for this.
+ */
+static int
+taskq_thread_spawn(taskq_t *tq)
+{
+ int spawning = 0;
+
+ if (!(tq->tq_flags & TASKQ_DYNAMIC))
+ return (0);
+
+ if ((tq->tq_nthreads + tq->tq_nspawn < tq->tq_maxthreads) &&
+ (tq->tq_flags & TASKQ_ACTIVE)) {
+ spawning = (++tq->tq_nspawn);
+ taskq_dispatch(dynamic_taskq, taskq_thread_spawn_task,
+ tq, TQ_NOSLEEP);
+ }
+
+ return (spawning);
+}
+
+/*
+ * Threads in a dynamic taskq should only exit once it has been completely
+ * drained and no other threads are actively servicing tasks. This prevents
+ * threads from being created and destroyed more than is required.
+ *
+ * The first thread is the thread list is treated as the primary thread.
+ * There is nothing special about the primary thread but in order to avoid
+ * all the taskq pids from changing we opt to make it long running.
+ */
+static int
+taskq_thread_should_stop(taskq_t *tq, taskq_thread_t *tqt)
+{
+ ASSERT(spin_is_locked(&tq->tq_lock));
+
+ if (!(tq->tq_flags & TASKQ_DYNAMIC))
+ return (0);
+
+ if (list_first_entry(&(tq->tq_thread_list), taskq_thread_t,
+ tqt_thread_list) == tqt)
+ return (0);
+
+ return
+ ((tq->tq_nspawn == 0) && /* No threads are being spawned */
+ (tq->tq_nactive == 0) && /* No threads are handling tasks */
+ (tq->tq_nthreads > 1) && /* More than 1 thread is running */
+ (!taskq_next_ent(tq)) && /* There are no pending tasks */
+ (spl_taskq_thread_dynamic));/* Dynamic taskqs are allowed */
+}
+
static int
taskq_thread(void *args)
{
taskq_thread_t *tqt = args;
taskq_t *tq;
taskq_ent_t *t;
- struct list_head *pend_list;
+ int seq_tasks = 0;
ASSERT(tqt);
tq = tqt->tqt_tq;
current->flags |= PF_NOFREEZE;
+ #if defined(PF_MEMALLOC_NOIO)
+ (void) memalloc_noio_save();
+ #endif
+
sigfillset(&blocked);
sigprocmask(SIG_BLOCK, &blocked, NULL);
flush_signals(current);
spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
+
+ /* Immediately exit if more threads than allowed were created. */
+ if (tq->tq_nthreads >= tq->tq_maxthreads)
+ goto error;
+
tq->tq_nthreads++;
+ list_add_tail(&tqt->tqt_thread_list, &tq->tq_thread_list);
wake_up(&tq->tq_wait_waitq);
set_current_state(TASK_INTERRUPTIBLE);
if (list_empty(&tq->tq_pend_list) &&
list_empty(&tq->tq_prio_list)) {
+
+ if (taskq_thread_should_stop(tq, tqt)) {
+ wake_up_all(&tq->tq_wait_waitq);
+ break;
+ }
+
add_wait_queue_exclusive(&tq->tq_work_waitq, &wait);
spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
+
schedule();
+ seq_tasks = 0;
+
spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
remove_wait_queue(&tq->tq_work_waitq, &wait);
} else {
__set_current_state(TASK_RUNNING);
}
-
- if (!list_empty(&tq->tq_prio_list))
- pend_list = &tq->tq_prio_list;
- else if (!list_empty(&tq->tq_pend_list))
- pend_list = &tq->tq_pend_list;
- else
- pend_list = NULL;
-
- if (pend_list) {
- t = list_entry(pend_list->next,taskq_ent_t,tqent_list);
+ if ((t = taskq_next_ent(tq)) != NULL) {
list_del_init(&t->tqent_list);
/* In order to support recursively dispatching a
tqt->tqt_task = NULL;
/* For prealloc'd tasks, we don't free anything. */
- if ((tq->tq_flags & TASKQ_DYNAMIC) ||
- !(tqt->tqt_flags & TQENT_FLAG_PREALLOC))
+ if (!(tqt->tqt_flags & TQENT_FLAG_PREALLOC))
task_done(tq, t);
/* When the current lowest outstanding taskqid is
ASSERT3S(tq->tq_lowest_id, >, tqt->tqt_id);
}
+ /* Spawn additional taskq threads if required. */
+ if ((++seq_tasks) > spl_taskq_thread_sequential &&
+ taskq_thread_spawn(tq))
+ seq_tasks = 0;
+
tqt->tqt_id = 0;
tqt->tqt_flags = 0;
wake_up_all(&tq->tq_wait_waitq);
+ } else {
+ if (taskq_thread_should_stop(tq, tqt))
+ break;
}
set_current_state(TASK_INTERRUPTIBLE);
__set_current_state(TASK_RUNNING);
tq->tq_nthreads--;
list_del_init(&tqt->tqt_thread_list);
- kmem_free(tqt, sizeof(taskq_thread_t));
-
+error:
+ kmem_free(tqt, sizeof (taskq_thread_t));
spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
return (0);
}
+static taskq_thread_t *
+taskq_thread_create(taskq_t *tq)
+{
+ static int last_used_cpu = 0;
+ taskq_thread_t *tqt;
+
+ tqt = kmem_alloc(sizeof (*tqt), KM_PUSHPAGE);
+ INIT_LIST_HEAD(&tqt->tqt_thread_list);
+ INIT_LIST_HEAD(&tqt->tqt_active_list);
+ tqt->tqt_tq = tq;
+ tqt->tqt_id = 0;
+
+ tqt->tqt_thread = spl_kthread_create(taskq_thread, tqt,
+ "%s", tq->tq_name);
+ if (tqt->tqt_thread == NULL) {
+ kmem_free(tqt, sizeof (taskq_thread_t));
+ return (NULL);
+ }
+
+ if (spl_taskq_thread_bind) {
+ last_used_cpu = (last_used_cpu + 1) % num_online_cpus();
+ kthread_bind(tqt->tqt_thread, last_used_cpu);
+ }
+
+ if (spl_taskq_thread_priority)
+ set_user_nice(tqt->tqt_thread, PRIO_TO_NICE(tq->tq_pri));
+
+ wake_up_process(tqt->tqt_thread);
+
+ return (tqt);
+}
+
taskq_t *
taskq_create(const char *name, int nthreads, pri_t pri,
int minalloc, int maxalloc, uint_t flags)
{
- static int last_used_cpu = 0;
taskq_t *tq;
taskq_thread_t *tqt;
- int rc = 0, i, j = 0;
+ int count = 0, rc = 0, i;
ASSERT(name != NULL);
- ASSERT(pri <= maxclsyspri);
ASSERT(minalloc >= 0);
ASSERT(maxalloc <= INT_MAX);
- ASSERT(!(flags & (TASKQ_CPR_SAFE | TASKQ_DYNAMIC))); /* Unsupported */
+ ASSERT(!(flags & (TASKQ_CPR_SAFE))); /* Unsupported */
/* Scale the number of threads using nthreads as a percentage */
if (flags & TASKQ_THREADS_CPU_PCT) {
nthreads = MAX((num_online_cpus() * nthreads) / 100, 1);
}
- tq = kmem_alloc(sizeof(*tq), KM_PUSHPAGE);
+ tq = kmem_alloc(sizeof (*tq), KM_PUSHPAGE);
if (tq == NULL)
return (NULL);
spin_lock_init(&tq->tq_lock);
- spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
INIT_LIST_HEAD(&tq->tq_thread_list);
INIT_LIST_HEAD(&tq->tq_active_list);
- tq->tq_name = name;
- tq->tq_nactive = 0;
- tq->tq_nthreads = 0;
- tq->tq_pri = pri;
- tq->tq_minalloc = minalloc;
- tq->tq_maxalloc = maxalloc;
- tq->tq_nalloc = 0;
- tq->tq_flags = (flags | TQ_ACTIVE);
- tq->tq_next_id = 1;
- tq->tq_lowest_id = 1;
+ tq->tq_name = strdup(name);
+ tq->tq_nactive = 0;
+ tq->tq_nthreads = 0;
+ tq->tq_nspawn = 0;
+ tq->tq_maxthreads = nthreads;
+ tq->tq_pri = pri;
+ tq->tq_minalloc = minalloc;
+ tq->tq_maxalloc = maxalloc;
+ tq->tq_nalloc = 0;
+ tq->tq_flags = (flags | TASKQ_ACTIVE);
+ tq->tq_next_id = 1;
+ tq->tq_lowest_id = 1;
INIT_LIST_HEAD(&tq->tq_free_list);
INIT_LIST_HEAD(&tq->tq_pend_list);
INIT_LIST_HEAD(&tq->tq_prio_list);
init_waitqueue_head(&tq->tq_work_waitq);
init_waitqueue_head(&tq->tq_wait_waitq);
- if (flags & TASKQ_PREPOPULATE)
+ if (flags & TASKQ_PREPOPULATE) {
+ spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
+
for (i = 0; i < minalloc; i++)
task_done(tq, task_alloc(tq, TQ_PUSHPAGE | TQ_NEW));
- spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
+ spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
+ }
+
+ if ((flags & TASKQ_DYNAMIC) && spl_taskq_thread_dynamic)
+ nthreads = 1;
for (i = 0; i < nthreads; i++) {
- tqt = kmem_alloc(sizeof(*tqt), KM_PUSHPAGE);
- INIT_LIST_HEAD(&tqt->tqt_thread_list);
- INIT_LIST_HEAD(&tqt->tqt_active_list);
- tqt->tqt_tq = tq;
- tqt->tqt_id = 0;
-
- tqt->tqt_thread = spl_kthread_create(taskq_thread, tqt,
- "%s/%d", name, i);
- if (tqt->tqt_thread) {
- list_add(&tqt->tqt_thread_list, &tq->tq_thread_list);
- if (spl_taskq_thread_bind) {
- last_used_cpu = (last_used_cpu + 1) % num_online_cpus();
- kthread_bind(tqt->tqt_thread, last_used_cpu);
- }
- set_user_nice(tqt->tqt_thread, PRIO_TO_NICE(pri));
- wake_up_process(tqt->tqt_thread);
- j++;
- } else {
- kmem_free(tqt, sizeof(taskq_thread_t));
+ tqt = taskq_thread_create(tq);
+ if (tqt == NULL)
rc = 1;
- }
+ else
+ count++;
}
/* Wait for all threads to be started before potential destroy */
- wait_event(tq->tq_wait_waitq, tq->tq_nthreads == j);
+ wait_event(tq->tq_wait_waitq, tq->tq_nthreads == count);
if (rc) {
taskq_destroy(tq);
ASSERT(tq);
spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
- tq->tq_flags &= ~TQ_ACTIVE;
+ tq->tq_flags &= ~TASKQ_ACTIVE;
spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
- /* TQ_ACTIVE cleared prevents new tasks being added to pending */
+ /*
+ * When TASKQ_ACTIVE is clear new tasks may not be added nor may
+ * new worker threads be spawned for dynamic taskq.
+ */
+ if (dynamic_taskq != NULL)
+ taskq_wait_outstanding(dynamic_taskq, 0);
+
taskq_wait(tq);
spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
*/
while (!list_empty(&tq->tq_thread_list)) {
tqt = list_entry(tq->tq_thread_list.next,
- taskq_thread_t, tqt_thread_list);
+ taskq_thread_t, tqt_thread_list);
thread = tqt->tqt_thread;
spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
task_free(tq, t);
}
- ASSERT(tq->tq_nthreads == 0);
- ASSERT(tq->tq_nalloc == 0);
+ ASSERT0(tq->tq_nthreads);
+ ASSERT0(tq->tq_nalloc);
+ ASSERT0(tq->tq_nspawn);
ASSERT(list_empty(&tq->tq_thread_list));
ASSERT(list_empty(&tq->tq_active_list));
ASSERT(list_empty(&tq->tq_free_list));
spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
- kmem_free(tq, sizeof(taskq_t));
+ strfree(tq->tq_name);
+ kmem_free(tq, sizeof (taskq_t));
}
EXPORT_SYMBOL(taskq_destroy);
int
spl_taskq_init(void)
{
- /* Solaris creates a dynamic taskq of up to 64 threads, however in
- * a Linux environment 1 thread per-core is usually about right */
- system_taskq = taskq_create("spl_system_taskq", num_online_cpus(),
- minclsyspri, 4, 512, TASKQ_PREPOPULATE);
+ system_taskq = taskq_create("spl_system_taskq", MAX(boot_ncpus, 64),
+ maxclsyspri, boot_ncpus, INT_MAX, TASKQ_PREPOPULATE|TASKQ_DYNAMIC);
if (system_taskq == NULL)
return (1);
+ dynamic_taskq = taskq_create("spl_dynamic_taskq", 1,
+ maxclsyspri, boot_ncpus, INT_MAX, TASKQ_PREPOPULATE);
+ if (dynamic_taskq == NULL) {
+ taskq_destroy(system_taskq);
+ return (1);
+ }
+
return (0);
}
void
spl_taskq_fini(void)
{
+ taskq_destroy(dynamic_taskq);
+ dynamic_taskq = NULL;
+
taskq_destroy(system_taskq);
+ system_taskq = NULL;
}
projects / mirror_spl.git / blobdiff