TSC as timecounter makes system lag
John Baldwin
jhb at freebsd.org
Fri Feb 24 17:57:32 UTC 2017
On Friday, February 24, 2017 10:50:19 PM Jia-Shiun Li wrote:
> On Fri, Feb 24, 2017 at 9:32 PM, Jia-Shiun Li <jiashiun at gmail.com> wrote:
>
> > On Fri, Feb 24, 2017 at 7:45 PM, Konstantin Belousov <kostikbel at gmail.com>
> > wrote:
> >
> >> On Fri, Feb 24, 2017 at 12:15:26PM +0800, Jia-Shiun Li wrote:
> >> > Tested working on E7400 against r313909. And changing timecounter
> >> from/to
> >> > TSC
> >> > correctly enables/disables C2.
> >> >
> >> > The latter part cpu_disable_c2_sleep++ is not needed. When
> >> > init_TSC_tc() got called timecounter is not yet tsc_timecounter.
> >> > inittimecounter() later will do the work calling tc_windup().
> >> >
> >>
> >> You mean, just this
> >> - if (cpu_deepest_sleep >= 2 && cpu_vendor_id == CPU_VENDOR_INTEL &&
> >> + if (cpu_vendor_id == CPU_VENDOR_INTEL &&
> >> is enough to fix the issue ? If yes, we can remove the cpu_deepest_sleep
> >> variable. This is John' observation, I think he would prefer to prepare
> >> the patch.
> >>
> >
> > Correct. That's enough.
> >
> >
> Since that's simple enough... patch attached.
> Tested against r313909 too.
Thanks for tracking down the cause and the patch!
--
John Baldwin
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