diff options
| author | jkim <jkim@FreeBSD.org> | 2011-06-22 16:40:45 +0000 |
|---|---|---|
| committer | jkim <jkim@FreeBSD.org> | 2011-06-22 16:40:45 +0000 |
| commit | 6da60ac39ebac7fcdb953979962ecb5f7658196a (patch) | |
| tree | 6b94ee5ab496f2fdf62f7cc9586df69cb8a162a4 /sys/kern/kern_clocksource.c | |
| parent | a0627f2e3f8b11a06d848f46dcd73032ded3bf5f (diff) | |
| download | FreeBSD-src-6da60ac39ebac7fcdb953979962ecb5f7658196a.zip FreeBSD-src-6da60ac39ebac7fcdb953979962ecb5f7658196a.tar.gz | |
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)
Diffstat (limited to 'sys/kern/kern_clocksource.c')
| -rw-r--r-- | sys/kern/kern_clocksource.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/sys/kern/kern_clocksource.c b/sys/kern/kern_clocksource.c index dd8bab5..ecfd408 100644 --- a/sys/kern/kern_clocksource.c +++ b/sys/kern/kern_clocksource.c @@ -59,6 +59,7 @@ __FBSDID("$FreeBSD$"); cyclic_clock_func_t cyclic_clock_func = NULL; #endif +int cpu_can_deep_sleep = 0; /* C3 state is available. */ int cpu_disable_deep_sleep = 0; /* Timer dies in C3. */ static void setuptimer(void); |
