I pulled this back from the 2.6 kernel to reduce some serious contention on the timerlist_lock when I had 8 gigabit cards runnings.
diff -u -r1.23 -r1.24
--- linux/linux/kernel/timer.c 2003/08/11 20:16:19 1.23
+++ linux/linux/kernel/timer.c 2003/10/01 21:09:20 1.24
@@ -207,6 +207,14 @@
int ret;
unsigned long flags;
+ /*
+ * This is a common optimization triggered by the
+ * networking code - if the timer is re-modified
+ * to be the same thing then just return:
+ */
+ if (timer->expires == expires && timer_pending(timer))
+ return 1;
+
spin_lock_irqsave(&timerlist_lock, flags);
timer->expires = expires;
ret = detach_timer(timer);