From: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: tglx@linutronix.de, mingo@redhat.com, bp@suse.de,
lenb@kernel.org, rjw@rjwysocki.net, mgorman@techsingularity.net,
x86@kernel.org, linux-pm@vger.kernel.org,
viresh.kumar@linaro.org, juri.lelli@arm.com,
linux-kernel@vger.kernel.org
Subject: Re: [RFC/RFT] [PATCH 03/10] cpufreq: intel_pstate: Utility functions to boost HWP performance limits
Date: Wed, 16 May 2018 08:41:13 -0700 [thread overview]
Message-ID: <1526485273.61700.14.camel@linux.intel.com> (raw)
In-Reply-To: <20180516072202.GV12217@hirez.programming.kicks-ass.net>
On Wed, 2018-05-16 at 09:22 +0200, Peter Zijlstra wrote:
> On Tue, May 15, 2018 at 09:49:04PM -0700, Srinivas Pandruvada wrote:
> > Setup necessary infrastructure to be able to boost HWP performance
> > on a
> > remote CPU. First initialize data structure to be able to use
> > smp_call_function_single_async(). The boost up function simply set
> > HWP
> > min to HWP max value and EPP to 0. The boost down function simply
> > restores
> > to last cached HWP Request value.
> >
> > To avoid reading HWP Request MSR during dynamic update, the HWP
> > Request
> > MSR value is cached in the local memory. This caching is done
> > whenever
> > HWP request MSR is modified during driver init on in setpolicy()
> > callback
> > path.
>
> The patch does two independent things; best to split that.
I had that split before, but thought no one is consuming the cached
value in that patch, so combined them. If this is not a problem, it is
better to split the patch.
Thanks,
Srinivas
>
>
> > diff --git a/drivers/cpufreq/intel_pstate.c
> > b/drivers/cpufreq/intel_pstate.c
> > index f686bbe..dc7dfa9 100644
> > --- a/drivers/cpufreq/intel_pstate.c
> > +++ b/drivers/cpufreq/intel_pstate.c
> > @@ -221,6 +221,9 @@ struct global_params {
> > * preference/bias
> > * @epp_saved: Saved EPP/EPB during system suspend
> > or CPU offline
> > * operation
> > + * @hwp_req_cached: Cached value of the last HWP request
> > MSR
>
> That's simply not true given the code below.
>
> > @@ -763,6 +768,7 @@ static void intel_pstate_hwp_set(unsigned int
> > cpu)
> > intel_pstate_set_epb(cpu, epp);
> > }
> > skip_epp:
> > + cpu_data->hwp_req_cached = value;
> > wrmsrl_on_cpu(cpu, MSR_HWP_REQUEST, value);
> > }
> >
> > @@ -1381,6 +1387,39 @@ static void
> > intel_pstate_get_cpu_pstates(struct cpudata *cpu)
> > intel_pstate_set_min_pstate(cpu);
> > }
> >
> > +
> > +static inline void intel_pstate_hwp_boost_up(struct cpudata *cpu)
> > +{
> > + u64 hwp_req;
> > + u8 max;
> > +
> > + max = (u8) (cpu->hwp_req_cached >> 8);
> > +
> > + hwp_req = cpu->hwp_req_cached & ~GENMASK_ULL(31, 24);
> > + hwp_req = (hwp_req & ~GENMASK_ULL(7, 0)) | max;
> > +
> > + wrmsrl(MSR_HWP_REQUEST, hwp_req);
> > +}
> > +
> > +static inline void intel_pstate_hwp_boost_down(struct cpudata
> > *cpu)
> > +{
> > + wrmsrl(MSR_HWP_REQUEST, cpu->hwp_req_cached);
> > +}
>
> This is not a traditional msr shadow; that would be updated on every
> wrmsr. There is not a comment in sight explaining why this one is
> different.
next prev parent reply other threads:[~2018-05-16 15:41 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-16 4:49 [RFC/RFT] [PATCH 00/10] Intel_pstate: HWP Dynamic performance boost Srinivas Pandruvada
2018-05-16 4:49 ` [RFC/RFT] [PATCH 01/10] x86,sched: Add support for frequency invariance Srinivas Pandruvada
2018-05-16 9:56 ` Peter Zijlstra
2018-05-16 4:49 ` [RFC/RFT] [PATCH 02/10] cpufreq: intel_pstate: Conditional frequency invariant accounting Srinivas Pandruvada
2018-05-16 7:16 ` Peter Zijlstra
2018-05-16 7:29 ` Peter Zijlstra
2018-05-16 9:07 ` Rafael J. Wysocki
2018-05-16 17:32 ` Srinivas Pandruvada
2018-05-16 15:19 ` Juri Lelli
2018-05-16 15:47 ` Peter Zijlstra
2018-05-16 16:31 ` Juri Lelli
2018-05-17 10:59 ` Juri Lelli
2018-05-17 15:04 ` Juri Lelli
2018-05-17 15:41 ` Srinivas Pandruvada
2018-05-17 16:16 ` Peter Zijlstra
2018-05-17 16:42 ` Srinivas Pandruvada
2018-05-17 16:56 ` Rafael J. Wysocki
2018-05-17 18:28 ` Peter Zijlstra
2018-05-18 7:36 ` Rafael J. Wysocki
2018-05-18 10:57 ` Patrick Bellasi
2018-05-18 11:29 ` Peter Zijlstra
2018-05-18 13:33 ` Patrick Bellasi
2018-05-30 16:57 ` Patrick Bellasi
2018-05-18 14:09 ` Valentin Schneider
2018-05-16 15:58 ` Srinivas Pandruvada
2018-05-16 4:49 ` [RFC/RFT] [PATCH 03/10] cpufreq: intel_pstate: Utility functions to boost HWP performance limits Srinivas Pandruvada
2018-05-16 7:22 ` Peter Zijlstra
2018-05-16 9:15 ` Rafael J. Wysocki
2018-05-16 10:43 ` Peter Zijlstra
2018-05-16 15:39 ` Srinivas Pandruvada
2018-05-16 15:41 ` Srinivas Pandruvada [this message]
2018-05-16 4:49 ` [RFC/RFT] [PATCH 04/10] cpufreq: intel_pstate: Add update_util_hook for HWP Srinivas Pandruvada
2018-05-16 4:49 ` [RFC/RFT] [PATCH 05/10] cpufreq: intel_pstate: HWP boost performance on IO Wake Srinivas Pandruvada
2018-05-16 7:37 ` Peter Zijlstra
2018-05-16 17:55 ` Srinivas Pandruvada
2018-05-17 8:19 ` Peter Zijlstra
2018-05-16 9:45 ` Rafael J. Wysocki
2018-05-16 19:28 ` Srinivas Pandruvada
2018-05-16 4:49 ` [RFC/RFT] [PATCH 06/10] cpufreq / sched: Add interface to get utilization values Srinivas Pandruvada
2018-05-16 6:40 ` Viresh Kumar
2018-05-16 22:25 ` Srinivas Pandruvada
2018-05-16 8:11 ` Peter Zijlstra
2018-05-16 22:40 ` Srinivas Pandruvada
2018-05-17 7:50 ` Peter Zijlstra
2018-05-16 4:49 ` [RFC/RFT] [PATCH 07/10] cpufreq: intel_pstate: HWP boost performance on busy task migrate Srinivas Pandruvada
2018-05-16 9:49 ` Rafael J. Wysocki
2018-05-16 20:59 ` Srinivas Pandruvada
2018-05-16 4:49 ` [RFC/RFT] [PATCH 08/10] cpufreq: intel_pstate: Dyanmically update busy pct Srinivas Pandruvada
2018-05-16 7:43 ` Peter Zijlstra
2018-05-16 7:47 ` Peter Zijlstra
2018-05-16 4:49 ` [RFC/RFT] [PATCH 09/10] cpufreq: intel_pstate: New sysfs entry to control HWP boost Srinivas Pandruvada
2018-05-16 4:49 ` [RFC/RFT] [PATCH 10/10] cpufreq: intel_pstate: enable boost for SKX Srinivas Pandruvada
2018-05-16 7:49 ` Peter Zijlstra
2018-05-16 15:46 ` Srinivas Pandruvada
2018-05-16 15:54 ` Peter Zijlstra
2018-05-17 0:52 ` Srinivas Pandruvada
2018-05-16 6:49 ` [RFC/RFT] [PATCH 00/10] Intel_pstate: HWP Dynamic performance boost Juri Lelli
2018-05-16 15:43 ` Srinivas Pandruvada
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