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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.

  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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