Messages in this thread | | | Date | Sat, 1 Mar 2008 13:31:27 +0100 | From | Pierre Ossman <> | Subject | Re: [RFC][PATCH] cpuidle: avoid singing capacitors |
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On Fri, 29 Feb 2008 16:44:07 -0500 lsorense@csclub.uwaterloo.ca (Lennart Sorensen) wrote:
> On Fri, Feb 29, 2008 at 07:38:12PM +0100, Pierre Ossman wrote: > > +/* > > + * The minimum number of ticks needed to not oscillate faster than > > + * 500 Hz. > > + */ > > +#define MIN_DEEP_INTERVAL (HZ / 500) > > What happens here if HZ < 500? Or does the fact that you have less than > 500HZ jiffies automatically imply that you can't go to sleep more than > the jiffy rate times per second?
A low HZ will still go to sleep very often (provided NO_HZ is in effect). But a HZ < 500 makes that number up there turn to zero. But the check further down makes sure that at least 1 tick passes. So that means it will not enter C3 more often than min(HZ, 500) Hz. Another reason to stop using jiffies.
-- -- Pierre Ossman
Linux kernel, MMC maintainer http://www.kernel.org PulseAudio, core developer http://pulseaudio.org rdesktop, core developer http://www.rdesktop.org
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