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.

1 files changed, 12 insertions, 5 deletions

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);