On Wednesday 22 June 2011 02:55 pm, Jung-uk Kim wrote:
> 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
I just realized kern_clocksource.c was excluded for arm and ia64.
Here is updated patch. Please ignore the previous one.
Thanks,
Jung-uk Kim
Index: sys/kern/kern_tc.c
===================================================================
--- sys/kern/kern_tc.c (revision 223446)
+++ sys/kern/kern_tc.c (working copy)
@@ -492,6 +492,12 @@ tc_windup(void)
/* Now is a good time to change timecounters. */
if (th->th_counter != timecounter) {
+#if !defined(__arm__) && !defined(__ia64__)
+ 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--;
+#endif
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 223446)
+++ 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 223446)
+++ 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 223446)
+++ sys/x86/x86/tsc.c (working copy)
@@ -452,6 +452,7 @@ init_TSC_tc(void)
if (cpu_can_deep_sleep && cpu_vendor_id == CPU_VENDOR_INTEL &&
(amd_pminfo & AMDPM_TSC_INVARIANT) == 0) {
tsc_timecounter.tc_quality = -1000;
+ tsc_timecounter.tc_flags |= TC_FLAGS_C3STOP;
if (bootverbose)
printf("TSC timecounter disabled: C3 enabled.\n");
goto init;
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