Update.
2000-06-13 Kaz Kylheku <kaz@ashi.footprints.net> A few optimizations. Got rid of unnecessary wakeups of timer threads, tightened up some critical regions and micro-optimized some list manipulation code. * sysdeps/pthread/timer_routines.c (__timer_thread_queue_timer): Returns int value now to indicate whether timer was queued at head. * sysdeps/pthread/posix-timer.h: Likewise. * sysdeps/pthread/timer_settime.c (timer_settime): Takes advantage of new return value from __timer_thread_queue_timer to avoid waking up timer thread unnecessarily. * sysdeps/pthread/posix-timer.h (timer_id2ptr): No longer checks inuse flag, because this requires mutex to be held. Callers updated to do the check when they have the mutex. * sysdeps/pthread/timer_getoverr.c: Add check for inuse here. * sysdeps/pthread/timer_settime.c (timer_settime): Tighter critical regions: avoids making system calls while holding timer mutex, and a few computations were moved outside of the mutex as well. * sysdeps/pthread/timer_gettime.c (timer_gettime): Likewise. * sysdeps/pthread/posix-timer.h (list_unlink_ip): Function name changed to list_unlink_ip, meaning idempotent. Pointer manipulation changed to get better better code out of gcc. * sysdeps/pthread/timer_routines.c (list_unlink): Non-idempotent version of list_unlink added here. * sysdeps/pthread/timer_delete.c: Use appropriate list unlink function in all places: idempotent one for timers, non-idempotent one for thread nodes. * sysdeps/pthread/timer_settime: Likewise. * sysdeps/pthread/timer_routines.c: Likewise.
This commit is contained in:
Ulrich Drepper
parent
1bfae4012a
commit
38161ac76e
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@ -1,3 +1,37 @@
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2000-06-13 Kaz Kylheku <kaz@ashi.footprints.net>
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A few optimizations. Got rid of unnecessary wakeups of timer threads,
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tightened up some critical regions and micro-optimized some list
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manipulation code.
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* sysdeps/pthread/timer_routines.c (__timer_thread_queue_timer):
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Returns int value now to indicate whether timer was queued at head.
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* sysdeps/pthread/posix-timer.h: Likewise.
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* sysdeps/pthread/timer_settime.c (timer_settime): Takes advantage of
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new return value from __timer_thread_queue_timer to avoid waking
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up timer thread unnecessarily.
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* sysdeps/pthread/posix-timer.h (timer_id2ptr): No longer checks
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inuse flag, because this requires mutex to be held. Callers updated
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to do the check when they have the mutex.
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* sysdeps/pthread/timer_getoverr.c: Add check for inuse here.
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* sysdeps/pthread/timer_settime.c (timer_settime): Tighter critical
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regions: avoids making system calls while holding timer mutex, and
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a few computations were moved outside of the mutex as well.
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* sysdeps/pthread/timer_gettime.c (timer_gettime): Likewise.
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* sysdeps/pthread/posix-timer.h (list_unlink_ip): Function name changed
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to list_unlink_ip, meaning idempotent. Pointer manipulation
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changed to get better better code out of gcc.
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* sysdeps/pthread/timer_routines.c (list_unlink): Non-idempotent
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version of list_unlink added here.
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* sysdeps/pthread/timer_delete.c: Use appropriate list unlink
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function in all places: idempotent one for timers, non-idempotent
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one for thread nodes.
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* sysdeps/pthread/timer_settime: Likewise.
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* sysdeps/pthread/timer_routines.c: Likewise.
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2000-06-13 Ulrich Drepper <drepper@redhat.com>
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* sysdeps/unix/sysv/linux/bits/posix_opt.h (_POSIX_TIMERS): Define.
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@ -93,7 +93,7 @@ extern struct thread_node __timer_signal_thread_tclk;
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static inline struct timer_node *
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timer_id2ptr (timer_t timerid)
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{
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if (timerid >= 0 && timerid < TIMER_MAX && __timer_array[timerid].inuse)
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if (timerid >= 0 && timerid < TIMER_MAX)
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return &__timer_array[timerid];
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return NULL;
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@ -155,10 +155,17 @@ timespec_sub (struct timespec *diff, const struct timespec *left,
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/* We need one of the list functions in the other modules. */
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static inline void
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list_unlink (struct list_links *list)
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list_unlink_ip (struct list_links *list)
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{
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list->next->prev = list->prev;
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list->prev->next = list->next;
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struct list_links *lnext = list->next, *lprev = list->prev;
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lnext->prev = lprev;
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lprev->next = lnext;
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/* The suffix ip means idempotent; list_unlink_ip can be called
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* two or more times on the same node.
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*/
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list->next = list;
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list->prev = list;
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}
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@ -173,6 +180,6 @@ extern struct thread_node *__timer_thread_find_matching (const pthread_attr_t *d
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extern struct thread_node *__timer_thread_alloc (const pthread_attr_t *desired_attr, clockid_t);
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extern void __timer_dealloc (struct timer_node *timer);
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extern void __timer_thread_dealloc (struct thread_node *thread);
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extern void __timer_thread_queue_timer (struct thread_node *thread,
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extern int __timer_thread_queue_timer (struct thread_node *thread,
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struct timer_node *insert);
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extern void __timer_thread_wakeup (struct thread_node *thread);
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@ -36,7 +36,7 @@ timer_delete (timerid)
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pthread_mutex_lock (&__timer_mutex);
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timer = timer_id2ptr (timerid);
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if (timer == NULL)
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if (timer == NULL || !timer->inuse)
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/* Invalid timer ID or the timer is not in use. */
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errno = EINVAL;
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else
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@ -58,7 +58,7 @@ timer_delete (timerid)
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}
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/* Remove timer from whatever queue it may be on and deallocate it. */
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list_unlink (&timer->links);
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list_unlink_ip (&timer->links);
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__timer_dealloc (timer);
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retval = 0;
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}
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@ -29,16 +29,15 @@ int
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timer_getoverrun (timerid)
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timer_t timerid;
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{
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struct timer_node *timer;
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int retval = -1;
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pthread_mutex_lock (&__timer_mutex);
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if (timer_id2ptr (timerid) == NULL)
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if ((timer = timer_id2ptr (timerid)) == NULL || !timer->inuse)
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errno = EINVAL;
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else
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{
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retval = 0; /* TODO: overrun counting not supported */
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}
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retval = 0; /* TODO: overrun counting not supported */
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pthread_mutex_lock (&__timer_mutex);
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@ -37,7 +37,7 @@ timer_gettime (timerid, value)
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pthread_mutex_lock (&__timer_mutex);
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timer = timer_id2ptr (timerid);
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if (timer == NULL)
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if (timer == NULL && !timer->inuse)
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/* Invalid timer ID or the timer is not in use. */
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errno = EINVAL;
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else
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@ -46,7 +46,9 @@ timer_gettime (timerid, value)
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if (timer->armed)
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{
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pthread_mutex_unlock (&__timer_mutex);
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clock_gettime (timer->clock, &now);
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pthread_mutex_lock (&__timer_mutex);
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timespec_sub (&value->it_value, &timer->expirytime, &now);
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}
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else
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@ -90,6 +90,20 @@ list_insbefore (struct list_links *list, struct list_links *newp)
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list_append (list, newp);
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}
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/*
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* Like list_unlink_ip, except that calling it on a node that
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* is already unlinked is disastrous rather than a noop.
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*/
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static inline void
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list_unlink (struct list_links *list)
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{
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struct list_links *lnext = list->next, *lprev = list->prev;
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lnext->prev = lprev;
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lprev->next = lnext;
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}
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static inline struct list_links *
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list_first (struct list_links *list)
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{
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@ -279,10 +293,7 @@ thread_cleanup (void *val)
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thread->current_timer = 0;
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if (list_isempty (&thread->timer_queue))
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{
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list_unlink (&thread->links);
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__timer_thread_dealloc (thread);
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}
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else
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(void) __timer_thread_start (thread);
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@ -394,7 +405,7 @@ thread_func (void *arg)
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if (timespec_compare (&now, &timer->expirytime) < 0)
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break;
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list_unlink (first);
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list_unlink_ip (first);
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if (__builtin_expect (timer->value.it_interval.tv_sec, 0) != 0
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|| timer->value.it_interval.tv_nsec != 0)
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@ -432,12 +443,16 @@ thread_func (void *arg)
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}
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/* Enqueue a timer in wakeup order in the thread's timer queue. */
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void
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/* Enqueue a timer in wakeup order in the thread's timer queue.
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Returns 1 if the timer was inserted at the head of the queue,
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causing the queue's next wakeup time to change. */
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int
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__timer_thread_queue_timer (struct thread_node *thread,
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struct timer_node *insert)
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{
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struct list_links *iter;
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int athead = 1;
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for (iter = list_first (&thread->timer_queue);
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iter != list_null (&thread->timer_queue);
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@ -447,9 +462,11 @@ __timer_thread_queue_timer (struct thread_node *thread,
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if (timespec_compare (&insert->expirytime, &timer->expirytime) < 0)
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break;
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athead = 0;
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}
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list_insbefore (iter, &insert->links);
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return athead;
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}
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@ -533,7 +550,7 @@ __timer_alloc (void)
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if (node != list_null (&timer_free_list))
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{
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struct timer_node *timer = timer_links2ptr (node);
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list_unlink (node);
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list_unlink_ip (node);
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timer->inuse = 1;
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return timer;
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}
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@ -35,11 +35,9 @@ timer_settime (timerid, flags, value, ovalue)
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struct timer_node *timer;
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struct thread_node *thread = NULL;
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struct timespec now;
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int have_now = 0;
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int have_now = 0, need_wakeup = 0;
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int retval = -1;
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pthread_mutex_lock (&__timer_mutex);
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timer = timer_id2ptr (timerid);
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if (timer == NULL)
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{
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@ -56,14 +54,40 @@ timer_settime (timerid, flags, value, ovalue)
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goto bail;
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}
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/* Will need to know current time since this is a relative timer;
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might as well make the system call outside of the lock now! */
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if ((flags & TIMER_ABSTIME) == 0)
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{
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clock_gettime (timer->clock, &now);
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have_now = 1;
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}
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pthread_mutex_lock (&__timer_mutex);
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/* One final check of timer validity; this one is possible only
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until we have the mutex, which guards the inuse flag. */
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if (!timer->inuse)
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{
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errno = EINVAL;
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goto unlock_bail;
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}
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if (ovalue != NULL)
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{
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ovalue->it_interval = timer->value.it_interval;
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if (timer->armed)
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{
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clock_gettime (timer->clock, &now);
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have_now = 1;
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if (! have_now)
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{
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pthread_mutex_unlock (&__timer_mutex);
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clock_gettime (timer->clock, &now);
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have_now = 1;
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pthread_mutex_lock (&__timer_mutex);
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}
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timespec_sub (&ovalue->it_value, &timer->expirytime, &now);
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}
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else
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@ -75,11 +99,12 @@ timer_settime (timerid, flags, value, ovalue)
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timer->value = *value;
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list_unlink (&timer->links);
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list_unlink_ip (&timer->links);
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timer->armed = 0;
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thread = timer->thread;
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/* A value of { 0, 0 } causes the timer to be stopped. */
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if (value->it_value.tv_sec != 0
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|| __builtin_expect (value->it_value.tv_nsec != 0, 1))
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{
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@ -87,25 +112,21 @@ timer_settime (timerid, flags, value, ovalue)
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/* The user specified the expiration time. */
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timer->expirytime = value->it_value;
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else
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{
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if (! have_now)
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clock_gettime (timer->clock, &now);
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timespec_add (&timer->expirytime, &now, &value->it_value);
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timespec_add (&timer->expirytime, &now, &value->it_value);
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}
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__timer_thread_queue_timer (thread, timer);
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/* Only need to wake up the thread if timer is inserted
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at the head of the queue. */
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need_wakeup = __timer_thread_queue_timer (thread, timer);
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timer->armed = 1;
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}
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retval = 0;
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bail:
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unlock_bail:
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pthread_mutex_unlock (&__timer_mutex);
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/* TODO: optimize this. Only need to wake up the thread if inserting
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a new timer at the head of the queue. */
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if (thread != NULL)
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bail:
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if (thread != NULL && need_wakeup)
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__timer_thread_wakeup (thread);
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return retval;
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