Date: Wed, 22 Jun 2011 13:02:20 -0400 From: Jung-uk Kim <jkim@FreeBSD.org> To: Andriy Gapon <avg@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r223426 - in head/sys: dev/acpica kern sys x86/x86 Message-ID: <201106221302.23375.jkim@FreeBSD.org> In-Reply-To: <4E021C8E.8010904@FreeBSD.org> References: <201106221640.p5MGejHY057164@svn.freebsd.org> <4E021C8E.8010904@FreeBSD.org>
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On Wednesday 22 June 2011 12:47 pm, Andriy Gapon wrote: > on 22/06/2011 19:40 Jung-uk Kim said the following: > > Author: jkim > > Date: Wed Jun 22 16:40:45 2011 > > New Revision: 223426 > > URL: http://svn.freebsd.org/changeset/base/223426 > > > > Log: > > Set negative quality to TSC timecounter when C3 state is > > enabled for Intel processors unless the invariant TSC bit of > > CPUID is set. Intel processors may stop incrementing TSC when > > DPSLP# pin is asserted, according to Intel processor manuals, i. > > e., TSC timecounter is useless if the processor can enter deep > > sleep state (C3/C4). This problem was accidentally uncovered by > > r222869, which increased timecounter quality of P-state invariant > > TSC, e.g., for Core2 Duo T5870 (Family 6, Model f) and Atom N270 > > (Family 6, Model 1c). > > > > Reported by: Fabian Keil (freebsd-listen at fabiankeil dot de) > > Ian FREISLICH (ianf at clue dot co dot za) > > Tested by: Fabian Keil (freebsd-listen at fabiankeil dot de) > > - Core2 Duo T5870 (C3 state available/enabled) > > jkim - Xeon X5150 (C3 state unavailable) > > I think that this change should have a counterpart similar to what > was done for event timers. That is, if a user forces use of TSC as > a timecounter vis sysctl and it is known that TSC stops in the deep > C-state, then the deep C-states should not be entered. This is > what cpu_disable_deep_sleep does for LAPIC timers. Yes. We have to teach tc_windup() to increase/decrease cpu_disable_deep_sleep. Currently, the user must disable C3 and force TSC timecounter manually if power consumption is not important, e.g., /etc/rc.conf: economy_cx_lowest="C2" /etc/sysctl.conf: kern.timecounter.hardware=TSC Jung-uk Kim
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