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From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Francisco Jerez <currojerez@riseup.net>
Cc: Linux PM <linux-pm@vger.kernel.org>,
	Linux Documentation <linux-doc@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
	Giovanni Gherdovich <ggherdovich@suse.cz>,
	Doug Smythies <dsmythies@telus.net>,
	Viresh Kumar <viresh.kumar@linaro.org>
Subject: Re: [PATCH v7] cpufreq: intel_pstate: Implement passive mode with HWP enabled
Date: Tue, 11 Aug 2020 17:33:49 +0200
Message-ID: <4931766.VNY61sLD3B@kreacher> (raw)
In-Reply-To: <87mu32atsy.fsf@riseup.net>

On Tuesday, August 11, 2020 2:51:41 AM CEST Francisco Jerez wrote:
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> "Rafael J. Wysocki" <rjw@rjwysocki.net> writes:
> 
> > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> >
> > Allow intel_pstate to work in the passive mode with HWP enabled and
> > make it set the HWP minimum performance limit (HWP floor) to the
> > P-state value given by the target frequency supplied by the cpufreq
> > governor, so as to prevent the HWP algorithm and the CPU scheduler
> > from working against each other, at least when the schedutil governor
> > is in use, and update the intel_pstate documentation accordingly.
> >
> > Among other things, this allows utilization clamps to be taken
> > into account, at least to a certain extent, when intel_pstate is
> > in use and makes it more likely that sufficient capacity for
> > deadline tasks will be provided.
> >
> > After this change, the resulting behavior of an HWP system with
> > intel_pstate in the passive mode should be close to the behavior
> > of the analogous non-HWP system with intel_pstate in the passive
> > mode, except that in the frequency range below the base frequency
> > (ie. the frequency retured by the base_frequency cpufreq attribute
> > in sysfs on HWP systems) the HWP algorithm is allowed to make the
> > CPU run at a frequency above the floor P-state set by intel_pstate,
> > with or without hardware coordination of P-states among CPUs in the
> > same package.
> >
> 
> The "frequency range below the base frequency" part of the paragraph
> above seems somewhat misleading, since AFAICT the same thing will happen
> in the P-state range above the base frequency. 

Fair enough.  I rephrased the changelog when applying the patch.

> Another minor comment below, other than that LGTM:

And this one has been fixed too.

> Reviewed-by: Francisco Jerez <currojerez@riseup.net>

Thanks!




  reply index

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-16 17:37 [PATCH v2 0/2] " Rafael J. Wysocki
2020-07-16 17:38 ` [PATCH v2 1/2] cpufreq: intel_pstate: Rearrange the storing of newv EPP values Rafael J. Wysocki
2020-07-16 17:42 ` [PATCH v2 2/2] cpufreq: intel_pstate: Implement passive mode with HWP enabled Rafael J. Wysocki
2020-07-27 15:13 ` [PATCH v3 0/2] " Rafael J. Wysocki
2020-07-27 15:15   ` [PATCH v3 1/2] cpufreq: intel_pstate: Rearrange the storing of new EPP values Rafael J. Wysocki
2020-07-27 15:17   ` [PATCH v3 2/2] cpufreq: intel_pstate: Implement passive mode with HWP enabled Rafael J. Wysocki
2020-07-28 15:09   ` [PATCH v4 0/2] " Rafael J. Wysocki
2020-07-28 15:11     ` [PATCH v4 1/2] cpufreq: intel_pstate: Rearrange the storing of new EPP values Rafael J. Wysocki
2020-07-30  1:31       ` Francisco Jerez
2020-07-28 15:13     ` [PATCH v4 2/2] cpufreq: intel_pstate: Implement passive mode with HWP enabled Rafael J. Wysocki
2020-08-01 23:21       ` Srinivas Pandruvada
2020-08-02 14:14         ` Doug Smythies
2020-08-02 19:20           ` Srinivas Pandruvada
2020-08-03 17:17       ` [PATCH v5] " Rafael J. Wysocki
2020-08-01 16:39     ` [PATCH v4 0/2] " Srinivas Pandruvada
2020-08-02 14:00       ` Doug Smythies
2020-08-02 18:39         ` Srinivas Pandruvada
2020-08-03  0:26           ` Doug Smythies
2020-08-03 17:23       ` Rafael J. Wysocki
2020-08-04 15:10   ` [PATCH v6] " Rafael J. Wysocki
2020-08-04 17:04     ` Doug Smythies
2020-08-05  9:34       ` Rafael J. Wysocki
2020-08-05 15:38         ` Srinivas Pandruvada
2020-08-05 16:28           ` Rafael J. Wysocki
2020-08-05 16:55   ` [PATCH v7] " Rafael J. Wysocki
2020-08-06  5:55     ` Doug Smythies
2020-08-06 11:25       ` Rafael J. Wysocki
2020-08-06 12:03     ` Rafael J. Wysocki
2020-08-10  0:44       ` Srinivas Pandruvada
2020-08-11  0:51       ` Francisco Jerez
2020-08-11 15:33         ` Rafael J. Wysocki [this message]
2020-08-17 21:06       ` Doug Smythies
2020-09-07  0:16         ` Doug Smythies

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