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
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");
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