From 6e453a67510a17f01b63835f18569e8c3939a38c Mon Sep 17 00:00:00 2001 From: Venki Pallipadi Date: Tue, 8 May 2007 00:27:44 -0700 Subject: Add support for deferrable timers Introduce a new flag for timers - deferrable: Timers that work normally when system is busy. But, will not cause CPU to come out of idle (just to service this timer), when CPU is idle. Instead, this timer will be serviced when CPU eventually wakes up with a subsequent non-deferrable timer. The main advantage of this is to avoid unnecessary timer interrupts when CPU is idle. If the routine currently called by a timer can wait until next event without any issues, this new timer can be used to setup timer event for that routine. This, with dynticks, allows CPUs to be lazy, allowing them to stay in idle for extended period of time by reducing unnecesary wakeup and thereby reducing the power consumption. This patch: Builds this new timer on top of existing timer infrastructure. It uses last bit in 'base' pointer of timer_list structure to store this deferrable timer flag. __next_timer_interrupt() function skips over these deferrable timers when CPU looks for next timer event for which it has to wake up. This is exported by a new interface init_timer_deferrable() that can be called in place of regular init_timer(). [akpm@linux-foundation.org: Privatise a #define] Signed-off-by: Venkatesh Pallipadi Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Oleg Nesterov Cc: Dave Jones Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/timer.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/timer.h') diff --git a/include/linux/timer.h b/include/linux/timer.h index 719113b652dd..e0c5c16c992f 100644 --- a/include/linux/timer.h +++ b/include/linux/timer.h @@ -37,6 +37,7 @@ extern struct tvec_t_base_s boot_tvec_bases; TIMER_INITIALIZER(_function, _expires, _data) void fastcall init_timer(struct timer_list * timer); +void fastcall init_timer_deferrable(struct timer_list *timer); static inline void setup_timer(struct timer_list * timer, void (*function)(unsigned long), -- cgit v1.2.3