Messages in this thread Patch in this message | | | Date | Tue, 28 Dec 2021 18:46:25 +0100 (CET) | From | Julia Lawall <> | Subject | Re: cpufreq: intel_pstate: map utilization into the pstate range |
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On Tue, 28 Dec 2021, Rafael J. Wysocki wrote:
> On Tue, Dec 28, 2021 at 5:58 PM Julia Lawall <julia.lawall@inria.fr> wrote: > > > > I looked a bit more into why pstate 20 is always using the least energy. I > > have just one thread spinning for 10 seconds, I use a fixed value for the > > pstate, and I measure the energy usage with turbostat. > > How exactly do you fix the pstate?
diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index e7af18857371..19440b15454c 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -400,7 +402,7 @@ static void sugov_update_single_perf(struct update_util_data *hook, u64 time, sg_cpu->util = prev_util;
cpufreq_driver_adjust_perf(sg_cpu->cpu, map_util_perf(sg_cpu->bw_dl), - map_util_perf(sg_cpu->util), sg_cpu->max); + sysctl_sched_fixedfreq, sg_cpu->max);
sg_cpu->sg_policy->last_freq_update_time = time; } ------------------------------ sysctl_sched_fixedfreq is a variable that I added to sysfs.
> > > I tried this on a > > 2-socket Intel 6130 and a 4-socket Intel 6130. The experiment runs 40 > > times. > > > > There seem to be only two levels of CPU energy usage. On the 2-socket > > machine the energy usage is around 600J up to pstate 20 and around 1000J > > after that. On the 4-socket machine it is twice that. > > These are the package power numbers from turbostat, aren't they?
Yes.
julia
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