Date: Thu, 17 May 2007 10:59:12 -0700 From: Nate Lawson <nate@root.org> To: Peter Jeremy <peterjeremy@optushome.com.au> Cc: acpi@freebsd.org Subject: Re: PowerTOP for FreeBSD ? Message-ID: <464C97F0.5000709@root.org> In-Reply-To: <20070516193130.GG1162@turion.vk2pj.dyndns.org> References: <20070515050404.GK49628@obelix.dsto.defence.gov.au> <1179249135.1149.21.camel@vonnegut> <20070516032813.GB3773@obelix.dsto.defence.gov.au> <464AAC1E.7060002@root.org> <20070516193130.GG1162@turion.vk2pj.dyndns.org>
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Peter Jeremy wrote: > On 2007-May-16 00:00:46 -0700, Nate Lawson <nate@root.org> wrote: >> Normally timers tick every 1 us on FreeBSD. > > Unless something has changed massively, tradtiionally, hardclock > interrupts every 1msec and statclick interrupts at 128Hz (approx > 8msec). > Oops, yes it's every 1 ms (1/1000 sec). I didn't bother mentioning stat clock since it's derived from hardclock and that's the only one that makes the CPU exit its idle state. >> Most interrupts are >> serviced with no work to be performed, so it's just wasted computation. > > Using the lapic timer is an excellent example of this. By default it > runs at 2000Hz to run hardclock() every 1msec and statclock() every > 7.5 msec - just under 50% of the interrupts are completely wasted. > Absolutely. -- Nate
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