Re: Unified tracing buffer

[Thomas Gleixner]

On Tue, 23 Sep 2008, Masami Hiramatsu wrote:
> # cat /sys/devices/system/cpu/cpu0/cpuidle/state3/usage
> 171210

C3 stops the TSC. So depending on how many C3 entries you have on the
different cores, your TSCs will drift apart. Some BIOSes do even a
lousy job trying to fixup the TSCs on exit from C3, which makes things
even worse.

>     C1:                  type[C1] promotion[--] demotion[--] latency[001] usage[00000016] duration[00000000000000000000]
>     C2:                  type[C2] promotion[--] demotion[--] latency[001] usage[00037969] duration[00000000000024288003]
>     C3:                  type[C3] promotion[--] demotion[--] latency[057] usage[00171818] duration[00000000001881257636]
> 
> Could these help you?

Yup, explains your TSC observation. Nothing we can do about. Broken by
system design :( Welcome in the wonderful world of Inhell/BIOS/ACPI !

Thanks,

	tglx
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/