Messages in this thread | | | Date | Tue, 23 Sep 2008 12:38:36 -0700 | From | "Martin Bligh" <> | Subject | Re: Unified tracing buffer |
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On Tue, Sep 23, 2008 at 12:36 PM, Thomas Gleixner <tglx@linutronix.de> wrote: > 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 !
We have linux patches that sync the TSC on exit_idle. I'll see if I can get Michael to send them out.
M.
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