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authorUlrich Drepper <drepper@redhat.com>2000-06-14 06:13:45 +0000
committerUlrich Drepper <drepper@redhat.com>2000-06-14 06:13:45 +0000
commit38161ac76efe4c50f13e244903a44645023fec83 (patch)
treee6dc04e6c057d7536f0927162ae40e756e621ee1 /linuxthreads
parent1bfae4012a34b5bf976ff0ddfe65f535b86a22f2 (diff)
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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.
Diffstat (limited to 'linuxthreads')
-rw-r--r--linuxthreads/ChangeLog34
-rw-r--r--linuxthreads/sysdeps/pthread/posix-timer.h17
-rw-r--r--linuxthreads/sysdeps/pthread/timer_delete.c4
-rw-r--r--linuxthreads/sysdeps/pthread/timer_getoverr.c7
-rw-r--r--linuxthreads/sysdeps/pthread/timer_gettime.c4
-rw-r--r--linuxthreads/sysdeps/pthread/timer_routines.c31
-rw-r--r--linuxthreads/sysdeps/pthread/timer_settime.c55
7 files changed, 116 insertions, 36 deletions
diff --git a/linuxthreads/ChangeLog b/linuxthreads/ChangeLog
index 795c064f90..121eceb83e 100644
--- a/linuxthreads/ChangeLog
+++ b/linuxthreads/ChangeLog
@@ -1,3 +1,37 @@
+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.
+
2000-06-13 Ulrich Drepper <drepper@redhat.com>
* sysdeps/unix/sysv/linux/bits/posix_opt.h (_POSIX_TIMERS): Define.
diff --git a/linuxthreads/sysdeps/pthread/posix-timer.h b/linuxthreads/sysdeps/pthread/posix-timer.h
index bb66c2d3d8..feeff39fa8 100644
--- a/linuxthreads/sysdeps/pthread/posix-timer.h
+++ b/linuxthreads/sysdeps/pthread/posix-timer.h
@@ -93,7 +93,7 @@ extern struct thread_node __timer_signal_thread_tclk;
static inline struct timer_node *
timer_id2ptr (timer_t timerid)
{
- if (timerid >= 0 && timerid < TIMER_MAX && __timer_array[timerid].inuse)
+ if (timerid >= 0 && timerid < TIMER_MAX)
return &__timer_array[timerid];
return NULL;
@@ -155,10 +155,17 @@ timespec_sub (struct timespec *diff, const struct timespec *left,
/* We need one of the list functions in the other modules. */
static inline void
-list_unlink (struct list_links *list)
+list_unlink_ip (struct list_links *list)
{
- list->next->prev = list->prev;
- list->prev->next = list->next;
+ struct list_links *lnext = list->next, *lprev = list->prev;
+
+ lnext->prev = lprev;
+ lprev->next = lnext;
+
+ /* The suffix ip means idempotent; list_unlink_ip can be called
+ * two or more times on the same node.
+ */
+
list->next = list;
list->prev = list;
}
@@ -173,6 +180,6 @@ extern struct thread_node *__timer_thread_find_matching (const pthread_attr_t *d
extern struct thread_node *__timer_thread_alloc (const pthread_attr_t *desired_attr, clockid_t);
extern void __timer_dealloc (struct timer_node *timer);
extern void __timer_thread_dealloc (struct thread_node *thread);
-extern void __timer_thread_queue_timer (struct thread_node *thread,
+extern int __timer_thread_queue_timer (struct thread_node *thread,
struct timer_node *insert);
extern void __timer_thread_wakeup (struct thread_node *thread);
diff --git a/linuxthreads/sysdeps/pthread/timer_delete.c b/linuxthreads/sysdeps/pthread/timer_delete.c
index 9e83ae1ab7..4636bf707a 100644
--- a/linuxthreads/sysdeps/pthread/timer_delete.c
+++ b/linuxthreads/sysdeps/pthread/timer_delete.c
@@ -36,7 +36,7 @@ timer_delete (timerid)
pthread_mutex_lock (&__timer_mutex);
timer = timer_id2ptr (timerid);
- if (timer == NULL)
+ if (timer == NULL || !timer->inuse)
/* Invalid timer ID or the timer is not in use. */
errno = EINVAL;
else
@@ -58,7 +58,7 @@ timer_delete (timerid)
}
/* Remove timer from whatever queue it may be on and deallocate it. */
- list_unlink (&timer->links);
+ list_unlink_ip (&timer->links);
__timer_dealloc (timer);
retval = 0;
}
diff --git a/linuxthreads/sysdeps/pthread/timer_getoverr.c b/linuxthreads/sysdeps/pthread/timer_getoverr.c
index f3aee45e8d..8630f57829 100644
--- a/linuxthreads/sysdeps/pthread/timer_getoverr.c
+++ b/linuxthreads/sysdeps/pthread/timer_getoverr.c
@@ -29,16 +29,15 @@ int
timer_getoverrun (timerid)
timer_t timerid;
{
+ struct timer_node *timer;
int retval = -1;
pthread_mutex_lock (&__timer_mutex);
- if (timer_id2ptr (timerid) == NULL)
+ if ((timer = timer_id2ptr (timerid)) == NULL || !timer->inuse)
errno = EINVAL;
else
- {
- retval = 0; /* TODO: overrun counting not supported */
- }
+ retval = 0; /* TODO: overrun counting not supported */
pthread_mutex_lock (&__timer_mutex);
diff --git a/linuxthreads/sysdeps/pthread/timer_gettime.c b/linuxthreads/sysdeps/pthread/timer_gettime.c
index 2db89a06eb..43b07598b7 100644
--- a/linuxthreads/sysdeps/pthread/timer_gettime.c
+++ b/linuxthreads/sysdeps/pthread/timer_gettime.c
@@ -37,7 +37,7 @@ timer_gettime (timerid, value)
pthread_mutex_lock (&__timer_mutex);
timer = timer_id2ptr (timerid);
- if (timer == NULL)
+ if (timer == NULL && !timer->inuse)
/* Invalid timer ID or the timer is not in use. */
errno = EINVAL;
else
@@ -46,7 +46,9 @@ timer_gettime (timerid, value)
if (timer->armed)
{
+ pthread_mutex_unlock (&__timer_mutex);
clock_gettime (timer->clock, &now);
+ pthread_mutex_lock (&__timer_mutex);
timespec_sub (&value->it_value, &timer->expirytime, &now);
}
else
diff --git a/linuxthreads/sysdeps/pthread/timer_routines.c b/linuxthreads/sysdeps/pthread/timer_routines.c
index 520f6ee2e7..ddf02fadd6 100644
--- a/linuxthreads/sysdeps/pthread/timer_routines.c
+++ b/linuxthreads/sysdeps/pthread/timer_routines.c
@@ -90,6 +90,20 @@ list_insbefore (struct list_links *list, struct list_links *newp)
list_append (list, newp);
}
+/*
+ * Like list_unlink_ip, except that calling it on a node that
+ * is already unlinked is disastrous rather than a noop.
+ */
+
+static inline void
+list_unlink (struct list_links *list)
+{
+ struct list_links *lnext = list->next, *lprev = list->prev;
+
+ lnext->prev = lprev;
+ lprev->next = lnext;
+}
+
static inline struct list_links *
list_first (struct list_links *list)
{
@@ -279,10 +293,7 @@ thread_cleanup (void *val)
thread->current_timer = 0;
if (list_isempty (&thread->timer_queue))
- {
- list_unlink (&thread->links);
__timer_thread_dealloc (thread);
- }
else
(void) __timer_thread_start (thread);
@@ -394,7 +405,7 @@ thread_func (void *arg)
if (timespec_compare (&now, &timer->expirytime) < 0)
break;
- list_unlink (first);
+ list_unlink_ip (first);
if (__builtin_expect (timer->value.it_interval.tv_sec, 0) != 0
|| timer->value.it_interval.tv_nsec != 0)
@@ -432,12 +443,16 @@ thread_func (void *arg)
}
-/* Enqueue a timer in wakeup order in the thread's timer queue. */
-void
+/* Enqueue a timer in wakeup order in the thread's timer queue.
+ Returns 1 if the timer was inserted at the head of the queue,
+ causing the queue's next wakeup time to change. */
+
+int
__timer_thread_queue_timer (struct thread_node *thread,
struct timer_node *insert)
{
struct list_links *iter;
+ int athead = 1;
for (iter = list_first (&thread->timer_queue);
iter != list_null (&thread->timer_queue);
@@ -447,9 +462,11 @@ __timer_thread_queue_timer (struct thread_node *thread,
if (timespec_compare (&insert->expirytime, &timer->expirytime) < 0)
break;
+ athead = 0;
}
list_insbefore (iter, &insert->links);
+ return athead;
}
@@ -533,7 +550,7 @@ __timer_alloc (void)
if (node != list_null (&timer_free_list))
{
struct timer_node *timer = timer_links2ptr (node);
- list_unlink (node);
+ list_unlink_ip (node);
timer->inuse = 1;
return timer;
}
diff --git a/linuxthreads/sysdeps/pthread/timer_settime.c b/linuxthreads/sysdeps/pthread/timer_settime.c
index 63b117f797..858edc7657 100644
--- a/linuxthreads/sysdeps/pthread/timer_settime.c
+++ b/linuxthreads/sysdeps/pthread/timer_settime.c
@@ -35,11 +35,9 @@ timer_settime (timerid, flags, value, ovalue)
struct timer_node *timer;
struct thread_node *thread = NULL;
struct timespec now;
- int have_now = 0;
+ int have_now = 0, need_wakeup = 0;
int retval = -1;
- pthread_mutex_lock (&__timer_mutex);
-
timer = timer_id2ptr (timerid);
if (timer == NULL)
{
@@ -56,14 +54,40 @@ timer_settime (timerid, flags, value, ovalue)
goto bail;
}
+ /* Will need to know current time since this is a relative timer;
+ might as well make the system call outside of the lock now! */
+
+ if ((flags & TIMER_ABSTIME) == 0)
+ {
+ clock_gettime (timer->clock, &now);
+ have_now = 1;
+ }
+
+ pthread_mutex_lock (&__timer_mutex);
+
+ /* One final check of timer validity; this one is possible only
+ until we have the mutex, which guards the inuse flag. */
+
+ if (!timer->inuse)
+ {
+ errno = EINVAL;
+ goto unlock_bail;
+ }
+
if (ovalue != NULL)
{
ovalue->it_interval = timer->value.it_interval;
if (timer->armed)
{
- clock_gettime (timer->clock, &now);
- have_now = 1;
+ if (! have_now)
+ {
+ pthread_mutex_unlock (&__timer_mutex);
+ clock_gettime (timer->clock, &now);
+ have_now = 1;
+ pthread_mutex_lock (&__timer_mutex);
+ }
+
timespec_sub (&ovalue->it_value, &timer->expirytime, &now);
}
else
@@ -75,11 +99,12 @@ timer_settime (timerid, flags, value, ovalue)
timer->value = *value;
- list_unlink (&timer->links);
+ list_unlink_ip (&timer->links);
timer->armed = 0;
thread = timer->thread;
+ /* A value of { 0, 0 } causes the timer to be stopped. */
if (value->it_value.tv_sec != 0
|| __builtin_expect (value->it_value.tv_nsec != 0, 1))
{
@@ -87,25 +112,21 @@ timer_settime (timerid, flags, value, ovalue)
/* The user specified the expiration time. */
timer->expirytime = value->it_value;
else
- {
- if (! have_now)
- clock_gettime (timer->clock, &now);
-
- timespec_add (&timer->expirytime, &now, &value->it_value);
- }
+ timespec_add (&timer->expirytime, &now, &value->it_value);
- __timer_thread_queue_timer (thread, timer);
+ /* Only need to wake up the thread if timer is inserted
+ at the head of the queue. */
+ need_wakeup = __timer_thread_queue_timer (thread, timer);
timer->armed = 1;
}
retval = 0;
-bail:
+unlock_bail:
pthread_mutex_unlock (&__timer_mutex);
- /* TODO: optimize this. Only need to wake up the thread if inserting
- a new timer at the head of the queue. */
- if (thread != NULL)
+bail:
+ if (thread != NULL && need_wakeup)
__timer_thread_wakeup (thread);
return retval;