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New an improved taskq implementation for the SPL. It allows a
configurable number of threads like the Solaris version and almost all of the options are supported. Unfortunately, it appears to have made absolutely no difference to our performance numbers. I need to keep looking for where we are bottle necking. git-svn-id: https://outreach.scidac.gov/svn/spl/trunk@93 7e1ea52c-4ff2-0310-8f11-9dd32ca42a1c
This commit is contained in:
behlendo
+390
-72
@@ -6,109 +6,427 @@
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#define DEBUG_SUBSYSTEM S_TASKQ
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/*
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* Task queue interface
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*
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* The taskq_work_wrapper functions are used to manage the work_structs
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* which must be submitted to linux. The shim layer allocates a wrapper
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* structure for all items which contains a pointer to itself as well as
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* the real work to be performed. When the work item run the generic
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* handle is called which calls the real work function and then using
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* the self pointer frees the work_struct.
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/* NOTE: Must be called with tq->tq_lock held, returns a list_t which
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* is not attached to the free, work, or pending taskq lists.
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*/
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typedef struct taskq_work_wrapper {
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struct work_struct tww_work;
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task_func_t tww_func;
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void * tww_priv;
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} taskq_work_wrapper_t;
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static void
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taskq_work_handler(void *priv)
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static task_t *
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task_alloc(taskq_t *tq, uint_t flags)
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{
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taskq_work_wrapper_t *tww = priv;
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task_t *t;
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int count = 0;
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ENTRY;
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ASSERT(tww);
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ASSERT(tww->tww_func);
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ASSERT(tq);
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ASSERT(flags & (TQ_SLEEP | TQ_NOSLEEP)); /* One set */
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ASSERT(!((flags & TQ_SLEEP) && (flags & TQ_NOSLEEP))); /* Not both */
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ASSERT(spin_is_locked(&tq->tq_lock));
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retry:
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/* Aquire task_t's from free list if available */
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if (!list_empty(&tq->tq_free_list) && !(flags & TQ_NEW)) {
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t = list_entry(tq->tq_free_list.next, task_t, t_list);
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list_del_init(&t->t_list);
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RETURN(t);
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}
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/* Call the real function and free the wrapper */
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tww->tww_func(tww->tww_priv);
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kfree(tww);
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/* Free list is empty and memory allocs are prohibited */
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if (flags & TQ_NOALLOC)
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RETURN(NULL);
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/* Hit maximum task_t pool size */
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if (tq->tq_nalloc >= tq->tq_maxalloc) {
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if (flags & TQ_NOSLEEP)
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RETURN(NULL);
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/* Sleep periodically polling the free list for an available
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* task_t. If a full second passes and we have not found
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* one gives up and return a NULL to the caller. */
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if (flags & TQ_SLEEP) {
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spin_unlock_irq(&tq->tq_lock);
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schedule_timeout(HZ / 100);
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spin_lock_irq(&tq->tq_lock);
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if (count < 100)
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GOTO(retry, count++);
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RETURN(NULL);
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}
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/* Unreachable, TQ_SLEEP xor TQ_NOSLEEP */
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SBUG();
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}
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spin_unlock_irq(&tq->tq_lock);
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t = kmem_alloc(sizeof(task_t), flags & (TQ_SLEEP | TQ_NOSLEEP));
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spin_lock_irq(&tq->tq_lock);
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if (t) {
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spin_lock_init(&t->t_lock);
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INIT_LIST_HEAD(&t->t_list);
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t->t_id = 0;
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t->t_func = NULL;
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t->t_arg = NULL;
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tq->tq_nalloc++;
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}
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RETURN(t);
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}
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/* XXX - All flags currently ignored */
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taskqid_t
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__taskq_dispatch(taskq_t *tq, task_func_t func, void *priv, uint_t flags)
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/* NOTE: Must be called with tq->tq_lock held, expectes the task_t
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* to already be removed from the free, work, or pending taskq lists.
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*/
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static void
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task_free(taskq_t *tq, task_t *t)
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{
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ENTRY;
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ASSERT(tq);
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ASSERT(t);
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ASSERT(spin_is_locked(&tq->tq_lock));
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ASSERT(list_empty(&t->t_list));
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kmem_free(t, sizeof(task_t));
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tq->tq_nalloc--;
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EXIT;
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}
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/* NOTE: Must be called with tq->tq_lock held, either destroyes the
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* task_t if too many exist or moves it to the free list for later use.
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*/
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static void
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task_done(taskq_t *tq, task_t *t)
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{
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struct workqueue_struct *wq = tq;
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taskq_work_wrapper_t *tww;
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int rc;
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ENTRY;
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ASSERT(tq);
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ASSERT(t);
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ASSERT(spin_is_locked(&tq->tq_lock));
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list_del_init(&t->t_list);
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if (tq->tq_nalloc <= tq->tq_minalloc) {
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t->t_id = 0;
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t->t_func = NULL;
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t->t_arg = NULL;
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list_add(&t->t_list, &tq->tq_free_list);
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} else {
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task_free(tq, t);
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}
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EXIT;
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}
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/* Taskqid's are handed out in a monotonically increasing fashion per
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* taskq_t. We don't handle taskqid wrapping yet, but fortuntely it isi
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* a 64-bit value so this is probably never going to happen. The lowest
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* pending taskqid is stored in the taskq_t to make it easy for any
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* taskq_wait()'ers to know if the tasks they're waiting for have
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* completed. Unfortunately, tq_task_lowest is kept up to date is
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* a pretty brain dead way, something more clever should be done.
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*/
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static int
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taskq_wait_check(taskq_t *tq, taskqid_t id)
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{
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RETURN(tq->tq_lowest_id >= id);
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}
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/* Expected to wait for all previously scheduled tasks to complete. We do
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* not need to wait for tasked scheduled after this call to complete. In
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* otherwords we do not need to drain the entire taskq. */
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void
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__taskq_wait_id(taskq_t *tq, taskqid_t id)
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{
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ENTRY;
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ASSERT(tq);
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wait_event(tq->tq_wait_waitq, taskq_wait_check(tq, id));
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EXIT;
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}
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EXPORT_SYMBOL(__taskq_wait_id);
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void
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__taskq_wait(taskq_t *tq)
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{
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taskqid_t id;
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ENTRY;
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ASSERT(tq);
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spin_lock_irq(&tq->tq_lock);
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id = tq->tq_next_id;
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spin_unlock_irq(&tq->tq_lock);
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__taskq_wait_id(tq, id);
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EXIT;
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}
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EXPORT_SYMBOL(__taskq_wait);
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int
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__taskq_member(taskq_t *tq, void *t)
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{
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int i;
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ENTRY;
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ASSERT(tq);
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ASSERT(t);
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for (i = 0; i < tq->tq_nthreads; i++)
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if (tq->tq_threads[i] == (struct task_struct *)t)
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RETURN(1);
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RETURN(0);
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}
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EXPORT_SYMBOL(__taskq_member);
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taskqid_t
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__taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t flags)
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{
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task_t *t;
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taskqid_t rc = 0;
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ENTRY;
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ASSERT(tq);
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ASSERT(func);
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if (unlikely(in_atomic() && (flags & TQ_SLEEP))) {
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CERROR("May schedule while atomic: %s/0x%08x/%d\n",
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current->comm, preempt_count(), current->pid);
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SBUG();
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}
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/* Use GFP_ATOMIC since this may be called in interrupt context */
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tww = (taskq_work_wrapper_t *)kmalloc(sizeof(*tww), GFP_ATOMIC);
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if (!tww)
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RETURN((taskqid_t)0);
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spin_lock_irq(&tq->tq_lock);
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INIT_WORK(&(tww->tww_work), taskq_work_handler, tww);
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tww->tww_func = func;
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tww->tww_priv = priv;
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/* Taskq being destroyed and all tasks drained */
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if (!(tq->tq_flags & TQ_ACTIVE))
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GOTO(out, rc = 0);
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rc = queue_work(wq, &(tww->tww_work));
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if (!rc) {
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kfree(tww);
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RETURN((taskqid_t)0);
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}
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/* Do not queue the task unless there is idle thread for it */
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ASSERT(tq->tq_nactive <= tq->tq_nthreads);
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if ((flags & TQ_NOQUEUE) && (tq->tq_nactive == tq->tq_nthreads))
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GOTO(out, rc = 0);
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RETURN((taskqid_t)wq);
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if ((t = task_alloc(tq, flags)) == NULL)
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GOTO(out, rc = 0);
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spin_lock(&t->t_lock);
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list_add(&t->t_list, &tq->tq_pend_list);
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t->t_id = rc = tq->tq_next_id;
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tq->tq_next_id++;
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t->t_func = func;
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t->t_arg = arg;
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spin_unlock(&t->t_lock);
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wake_up(&tq->tq_work_waitq);
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out:
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spin_unlock_irq(&tq->tq_lock);
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RETURN(rc);
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}
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EXPORT_SYMBOL(__taskq_dispatch);
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/* XXX - We must fully implement dynamic workqueues since they make a
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* significant impact in terms of performance. For now I've made
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* a trivial compromise. If you ask for one thread you get one
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* thread, if you ask for more than that you get one per core.
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* It's unclear if you ever really need/want more than one per-core
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* anyway. More analysis is required.
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*
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* name - Workqueue names are limited to 10 chars
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* pri - Ignore priority
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* min - Ignored until this is a dynamic thread pool
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* max - Ignored until this is a dynamic thread pool
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* flags - Ignored until this is a dynamic thread_pool
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*/
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/* NOTE: Must be called with tq->tq_lock held */
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static taskqid_t
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taskq_lowest_id(taskq_t *tq)
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{
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taskqid_t lowest_id = ~0;
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task_t *t;
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ENTRY;
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ASSERT(tq);
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ASSERT(spin_is_locked(&tq->tq_lock));
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list_for_each_entry(t, &tq->tq_pend_list, t_list)
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if (t->t_id < lowest_id)
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lowest_id = t->t_id;
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list_for_each_entry(t, &tq->tq_work_list, t_list)
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if (t->t_id < lowest_id)
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lowest_id = t->t_id;
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RETURN(lowest_id);
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}
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static int
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taskq_thread(void *args)
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{
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DECLARE_WAITQUEUE(wait, current);
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sigset_t blocked;
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taskqid_t id;
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taskq_t *tq = args;
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task_t *t;
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ENTRY;
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ASSERT(tq);
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current->flags |= PF_NOFREEZE;
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sigfillset(&blocked);
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sigprocmask(SIG_BLOCK, &blocked, NULL);
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flush_signals(current);
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spin_lock_irq(&tq->tq_lock);
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tq->tq_nthreads++;
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wake_up(&tq->tq_wait_waitq);
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set_current_state(TASK_INTERRUPTIBLE);
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while (!kthread_should_stop()) {
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add_wait_queue(&tq->tq_work_waitq, &wait);
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if (list_empty(&tq->tq_pend_list)) {
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spin_unlock_irq(&tq->tq_lock);
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schedule();
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spin_lock_irq(&tq->tq_lock);
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} else {
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__set_current_state(TASK_RUNNING);
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}
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remove_wait_queue(&tq->tq_work_waitq, &wait);
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if (!list_empty(&tq->tq_pend_list)) {
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t = list_entry(tq->tq_pend_list.next, task_t, t_list);
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list_del_init(&t->t_list);
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list_add(&t->t_list, &tq->tq_work_list);
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tq->tq_nactive++;
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spin_unlock_irq(&tq->tq_lock);
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/* Perform the requested task */
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t->t_func(t->t_arg);
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spin_lock_irq(&tq->tq_lock);
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tq->tq_nactive--;
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id = t->t_id;
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task_done(tq, t);
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/* Update the lowest remaining taskqid yet to run */
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if (tq->tq_lowest_id == id) {
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tq->tq_lowest_id = taskq_lowest_id(tq);
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ASSERT(tq->tq_lowest_id > id);
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}
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wake_up_all(&tq->tq_wait_waitq);
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}
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set_current_state(TASK_INTERRUPTIBLE);
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}
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__set_current_state(TASK_RUNNING);
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tq->tq_nthreads--;
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spin_unlock_irq(&tq->tq_lock);
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RETURN(0);
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}
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taskq_t *
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__taskq_create(const char *name, int nthreads, pri_t pri,
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int minalloc, int maxalloc, uint_t flags)
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{
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taskq_t *tq;
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ENTRY;
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taskq_t *tq;
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struct task_struct *t;
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int rc = 0, i, j = 0;
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ENTRY;
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if (nthreads == 1)
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tq = create_singlethread_workqueue(name);
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else
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tq = create_workqueue(name);
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ASSERT(name != NULL);
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ASSERT(pri <= maxclsyspri);
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ASSERT(minalloc >= 0);
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ASSERT(maxalloc <= INT_MAX);
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ASSERT(!(flags & (TASKQ_CPR_SAFE | TASKQ_DYNAMIC))); /* Unsupported */
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return tq;
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tq = kmem_alloc(sizeof(*tq), KM_SLEEP);
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if (tq == NULL)
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RETURN(NULL);
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tq->tq_threads = kmem_alloc(nthreads * sizeof(t), KM_SLEEP);
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if (tq->tq_threads == NULL) {
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kmem_free(tq, sizeof(*tq));
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RETURN(NULL);
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}
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spin_lock_init(&tq->tq_lock);
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spin_lock_irq(&tq->tq_lock);
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tq->tq_name = name;
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tq->tq_nactive = 0;
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tq->tq_nthreads = 0;
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tq->tq_pri = pri;
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tq->tq_minalloc = minalloc;
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tq->tq_maxalloc = maxalloc;
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tq->tq_nalloc = 0;
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tq->tq_flags = (flags | TQ_ACTIVE);
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tq->tq_next_id = 1;
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tq->tq_lowest_id = 1;
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INIT_LIST_HEAD(&tq->tq_free_list);
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INIT_LIST_HEAD(&tq->tq_work_list);
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INIT_LIST_HEAD(&tq->tq_pend_list);
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init_waitqueue_head(&tq->tq_work_waitq);
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init_waitqueue_head(&tq->tq_wait_waitq);
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if (flags & TASKQ_PREPOPULATE)
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for (i = 0; i < minalloc; i++)
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task_done(tq, task_alloc(tq, TQ_SLEEP | TQ_NEW));
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spin_unlock_irq(&tq->tq_lock);
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for (i = 0; i < nthreads; i++) {
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t = kthread_create(taskq_thread, tq, "%s/%d", name, i);
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if (t) {
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tq->tq_threads[i] = t;
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kthread_bind(t, i % num_online_cpus());
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set_user_nice(t, PRIO_TO_NICE(pri));
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wake_up_process(t);
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j++;
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} else {
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tq->tq_threads[i] = NULL;
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rc = 1;
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}
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}
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/* Wait for all threads to be started before potential destroy */
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wait_event(tq->tq_wait_waitq, tq->tq_nthreads == j);
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if (rc) {
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__taskq_destroy(tq);
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tq = NULL;
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}
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RETURN(tq);
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}
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EXPORT_SYMBOL(__taskq_create);
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void
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__taskq_destroy(taskq_t *tq)
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{
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task_t *t;
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int i, nthreads;
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ENTRY;
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destroy_workqueue(tq);
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ASSERT(tq);
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spin_lock_irq(&tq->tq_lock);
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tq->tq_flags &= ~TQ_ACTIVE;
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spin_unlock_irq(&tq->tq_lock);
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/* TQ_ACTIVE cleared prevents new tasks being added to pending */
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__taskq_wait(tq);
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nthreads = tq->tq_nthreads;
|
||||
for (i = 0; i < nthreads; i++)
|
||||
if (tq->tq_threads[i])
|
||||
kthread_stop(tq->tq_threads[i]);
|
||||
|
||||
spin_lock_irq(&tq->tq_lock);
|
||||
|
||||
while (!list_empty(&tq->tq_free_list)) {
|
||||
t = list_entry(tq->tq_free_list.next, task_t, t_list);
|
||||
list_del_init(&t->t_list);
|
||||
task_free(tq, t);
|
||||
}
|
||||
|
||||
ASSERT(tq->tq_nthreads == 0);
|
||||
ASSERT(tq->tq_nalloc == 0);
|
||||
ASSERT(list_empty(&tq->tq_free_list));
|
||||
ASSERT(list_empty(&tq->tq_work_list));
|
||||
ASSERT(list_empty(&tq->tq_pend_list));
|
||||
|
||||
spin_unlock_irq(&tq->tq_lock);
|
||||
kmem_free(tq->tq_threads, nthreads * sizeof(task_t *));
|
||||
kmem_free(tq, sizeof(taskq_t));
|
||||
|
||||
EXIT;
|
||||
}
|
||||
EXPORT_SYMBOL(__taskq_destroy);
|
||||
|
||||
void
|
||||
__taskq_wait(taskq_t *tq)
|
||||
{
|
||||
ENTRY;
|
||||
flush_workqueue(tq);
|
||||
EXIT;
|
||||
}
|
||||
EXPORT_SYMBOL(__taskq_wait);
|
||||
|
||||
Reference in New Issue
Block a user