tree facfe4ad3bb3638d8ee6f6b3e7fc75a0a02e304a
parent 5466b456ed6748e0bfe02831e570004d4c04c1d7
author Arjan van de Ven <arjan@linux.intel.com> 1165746084 -0800
committer Linus Torvalds <torvalds@woody.osdl.org> 1165773442 -0800

[PATCH] round_jiffies infrastructure

Introduce a round_jiffies() function as well as a round_jiffies_relative()
function.  These functions round a jiffies value to the next whole second.
The primary purpose of this rounding is to cause all "we don't care exactly
when" timers to happen at the same jiffy.

This avoids multiple timers firing within the second for no real reason;
with dynamic ticks these extra timers cause wakeups from deep sleep CPU
sleep states and thus waste power.

The exact wakeup moment is skewed by the cpu number, to avoid all cpus from
waking up at the exact same time (and hitting the same lock/cachelines
there)

[akpm@osdl.org: fix variable type]
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>