Date: Wed, 22 Jun 2011 14:55:05 -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: <201106221455.07540.jkim@FreeBSD.org> In-Reply-To: <4E021C8E.8010904@FreeBSD.org> References: <201106221640.p5MGejHY057164@svn.freebsd.org> <4E021C8E.8010904@FreeBSD.org>
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--Boundary-00=_LqjAOQlSv1JdSAI Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline 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. Can you please review/test the attached patch? Also available from here: http://people.freebsd.org/~jkim/tc_c3stop.diff Thanks! Jung-uk Kim --Boundary-00=_LqjAOQlSv1JdSAI Content-Type: text/plain; charset="iso-8859-1"; name="tc_c3stop.diff" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="tc_c3stop.diff" Index: sys/kern/kern_tc.c =================================================================== --- sys/kern/kern_tc.c (revision 223426) +++ sys/kern/kern_tc.c (working copy) @@ -492,6 +492,10 @@ tc_windup(void) /* Now is a good time to change timecounters. */ if (th->th_counter != timecounter) { + if ((timecounter->tc_flags & TC_FLAGS_C3STOP) != 0) + cpu_disable_deep_sleep++; + if ((th->th_counter->tc_flags & TC_FLAGS_C3STOP) != 0) + cpu_disable_deep_sleep--; th->th_counter = timecounter; th->th_offset_count = ncount; tc_min_ticktock_freq = max(1, timecounter->tc_frequency / Index: sys/sparc64/sparc64/counter.c =================================================================== --- sys/sparc64/sparc64/counter.c (revision 223426) +++ sys/sparc64/sparc64/counter.c (working copy) @@ -98,6 +98,7 @@ sparc64_counter_init(const char *name, bus_space_t tc->tc_name = strdup(name, M_DEVBUF); tc->tc_priv = sc; tc->tc_quality = COUNTER_QUALITY; + tc->tc_flags = 0; tc_init(tc); } Index: sys/sys/timetc.h =================================================================== --- sys/sys/timetc.h (revision 223426) +++ sys/sys/timetc.h (working copy) @@ -57,6 +57,8 @@ struct timecounter { * another timecounter higher means better. Negative * means "only use at explicit request". */ + u_int tc_flags; +#define TC_FLAGS_C3STOP 1 /* Timer dies in C3. */ void *tc_priv; /* Pointer to the timecounter's private parts. */ Index: sys/x86/x86/tsc.c =================================================================== --- sys/x86/x86/tsc.c (revision 223426) +++ sys/x86/x86/tsc.c (working copy) @@ -451,6 +451,7 @@ init_TSC_tc(void) */ if (cpu_can_deep_sleep && cpu_vendor_id == CPU_VENDOR_INTEL && (amd_pminfo & AMDPM_TSC_INVARIANT) == 0) { + tsc_timecounter.tc_flags |= TC_FLAGS_C3STOP; tsc_timecounter.tc_quality = -1000; if (bootverbose) printf("TSC timecounter disabled: C3 enabled.\n"); --Boundary-00=_LqjAOQlSv1JdSAI--
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