Re: [PATCH 4/5] intel_pstate: Remove C0 tracking

Rafael J. Wysocki
2014-05-12T00:09:33Z

On Thursday, May 08, 2014 12:57:26 PM dirk.brandewie@gmail.com wrote:
> From: Dirk Brandewie <dirk.j.brandewie@intel.com>
>
> Commit fcb6a15c intel_pstate: Take core C0 time into account for core busy
> introduced a regression referenced below. The issue with "lockup"
> after suspend that this commit was addressing is now dealt with in the
> suspend path.
>
> References:
> https://bugzilla.kernel.org/show_bug.cgi?id=66581
> https://bugzilla.kernel.org/show_bug.cgi?id=75121
>
> Reported-by: Doug Smythies <dsmythies@telus.net>
> Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>

Do we need this in -stable?

> ---
> drivers/cpufreq/intel_pstate.c | 13 +------------
> 1 file changed, 1 insertion(+), 12 deletions(-)
>
> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
> index bb20881..4c26faf 100644
> --- a/drivers/cpufreq/intel_pstate.c
> +++ b/drivers/cpufreq/intel_pstate.c
> @@ -59,7 +59,6 @@ struct sample {
> int32_t core_pct_busy;
> u64 aperf;
> u64 mperf;
> - unsigned long long tsc;
> int freq;
> };
>
> @@ -100,7 +99,6 @@ struct cpudata {
>
> u64 prev_aperf;
> u64 prev_mperf;
> - unsigned long long prev_tsc;
> struct sample sample;
> };
>
> @@ -561,46 +559,37 @@ static inline void intel_pstate_calc_busy(struct cpudata *cpu,
> struct sample *sample)
> {
> int32_t core_pct;
> - int32_t c0_pct;
>
> core_pct = div_fp(int_tofp((sample->aperf)),
> int_tofp((sample->mperf)));
> core_pct = mul_fp(core_pct, int_tofp(100));
> FP_ROUNDUP(core_pct);
>
> - c0_pct = div_fp(int_tofp(sample->mperf), int_tofp(sample->tsc));
> -
> sample->freq = fp_toint(
> mul_fp(int_tofp(cpu->pstate.max_pstate * 1000), core_pct));
>
> - sample->core_pct_busy = mul_fp(core_pct, c0_pct);
> + sample->core_pct_busy = core_pct;
> }
>
> static inline void intel_pstate_sample(struct cpudata *cpu)
> {
> u64 aperf, mperf;
> - unsigned long long tsc;
>
> rdmsrl(MSR_IA32_APERF, aperf);
> rdmsrl(MSR_IA32_MPERF, mperf);
> - tsc = native_read_tsc();
>
> aperf = aperf >> FRAC_BITS;
> mperf = mperf >> FRAC_BITS;
> - tsc = tsc >> FRAC_BITS;
>
> cpu->sample.aperf = aperf;
> cpu->sample.mperf = mperf;
> - cpu->sample.tsc = tsc;
> cpu->sample.aperf -= cpu->prev_aperf;
> cpu->sample.mperf -= cpu->prev_mperf;
> - cpu->sample.tsc -= cpu->prev_tsc;
>
> intel_pstate_calc_busy(cpu, &cpu->sample);
>
> cpu->prev_aperf = aperf;
> cpu->prev_mperf = mperf;
> - cpu->prev_tsc = tsc;
> }
>
> static inline void intel_pstate_set_sample_time(struct cpudata *cpu)
>

--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.