From: Giovanni Gherdovich <ggherdovich@suse.cz>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@suse.de>,
Len Brown <lenb@kernel.org>,
"Rafael J . Wysocki" <rjw@rjwysocki.net>,
x86@kernel.org, linux-pm@vger.kernel.org,
linux-kernel@vger.kernel.org,
Mel Gorman <mgorman@techsingularity.net>,
Matt Fleming <matt@codeblueprint.co.uk>,
Viresh Kumar <viresh.kumar@linaro.org>,
Juri Lelli <juri.lelli@redhat.com>, Paul Turner <pjt@google.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Quentin Perret <qperret@qperret.net>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Doug Smythies <dsmythies@telus.net>
Subject: Re: [PATCH v4 2/6] x86,sched: Add support for frequency invariance on SKYLAKE_X
Date: Thu, 19 Dec 2019 21:29:17 +0100 [thread overview]
Message-ID: <1576787357.8929.12.camel@suse.cz> (raw)
In-Reply-To: <20191218200624.GI11457@worktop.programming.kicks-ass.net>
On Wed, 2019-12-18 at 21:06 +0100, Peter Zijlstra wrote:
> On Wed, Nov 13, 2019 at 01:46:50PM +0100, Giovanni Gherdovich wrote:
> > The scheduler needs the ratio freq_curr/freq_max for frequency-invariant
> > accounting. On SKYLAKE_X CPUs set freq_max to the highest frequency that can
> > be sustained by a group of at least 4 cores.
> >
> > From the changelog of commit 31e07522be56 ("tools/power turbostat: fix
> > decoding for GLM, DNV, SKX turbo-ratio limits"):
> >
> > > Newer processors do not hard-code the the number of cpus in each bin
> > > to {1, 2, 3, 4, 5, 6, 7, 8} Rather, they can specify any number
> > > of CPUS in each of the 8 bins:
> > >
> > > eg.
> > >
> > > ...
> > > 37 * 100.0 = 3600.0 MHz max turbo 4 active cores
> > > 38 * 100.0 = 3700.0 MHz max turbo 3 active cores
> > > 39 * 100.0 = 3800.0 MHz max turbo 2 active cores
> > > 39 * 100.0 = 3900.0 MHz max turbo 1 active cores
> > >
> > > could now look something like this:
> > >
> > > ...
> > > 37 * 100.0 = 3600.0 MHz max turbo 16 active cores
> > > 38 * 100.0 = 3700.0 MHz max turbo 8 active cores
> > > 39 * 100.0 = 3800.0 MHz max turbo 4 active cores
> > > 39 * 100.0 = 3900.0 MHz max turbo 2 active cores
> >
> > This encoding of turbo levels applies to both SKYLAKE_X and GOLDMONT/GOLDMONT_D,
> > but we treat these two classes in separate commits because their freq_max
> > values need to be different. For SKX we prefer a lower freq_max in the ratio
> > freq_curr/freq_max, allowing load and utilization to overshoot and the
> > schedutil governor to be more performance-oriented. Models from the Atom
> > series (such as GOLDMONT*) are handled in a forthcoming commit as they have to
> > favor power-efficiency over performance.
>
> Can we at least use a single function to decode both? A little like the
> below. I'm not married to the naming, but I think it is a little silly
> to have 2 different functions to decode the exact same MSRs.
>
> (one could even go as far as to make a boot param to override the {1,4}
> default core count for these things)
Sure, that was actually a gross oversight on my part for not seeing that.
Thanks for catching it and sketching a solution.
Giovanni
next prev parent reply other threads:[~2019-12-19 20:23 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-13 12:46 [PATCH v4 0/6] Add support for frequency invariance for (some) x86 Giovanni Gherdovich
2019-11-13 12:46 ` [PATCH v4 1/6] x86,sched: Add support for frequency invariance Giovanni Gherdovich
2019-11-24 7:49 ` Doug Smythies
2019-11-25 8:16 ` Doug Smythies
2019-11-25 9:16 ` Mel Gorman
2019-11-25 16:06 ` Giovanni Gherdovich
2019-11-26 5:59 ` Doug Smythies
2019-11-26 15:20 ` Giovanni Gherdovich
2019-11-27 7:32 ` Doug Smythies
2019-11-28 22:48 ` Doug Smythies
2019-12-19 10:48 ` Qais Yousef
2019-12-23 7:47 ` Doug Smythies
2019-12-23 14:07 ` Qais Yousef
2019-12-23 14:40 ` Qais Yousef
2019-12-23 16:34 ` Doug Smythies
2019-12-23 19:10 ` Qais Yousef
2019-12-24 1:16 ` Doug Smythies
2019-12-24 11:08 ` Qais Yousef
2019-12-02 16:34 ` Ionela Voinescu
2019-12-06 11:57 ` Giovanni Gherdovich
2019-12-18 19:34 ` Peter Zijlstra
2019-12-19 20:27 ` Giovanni Gherdovich
2019-11-13 12:46 ` [PATCH v4 2/6] x86,sched: Add support for frequency invariance on SKYLAKE_X Giovanni Gherdovich
2019-12-18 20:06 ` Peter Zijlstra
2019-12-19 20:29 ` Giovanni Gherdovich [this message]
2019-11-13 12:46 ` [PATCH v4 3/6] x86,sched: Add support for frequency invariance on XEON_PHI_KNL/KNM Giovanni Gherdovich
2019-12-18 20:22 ` Peter Zijlstra
2019-12-19 20:32 ` Giovanni Gherdovich
2019-11-13 12:46 ` [PATCH v4 4/6] x86,sched: Add support for frequency invariance on ATOM_GOLDMONT* Giovanni Gherdovich
2019-11-13 12:46 ` [PATCH v4 5/6] x86,sched: Add support for frequency invariance on ATOM Giovanni Gherdovich
2019-11-13 16:50 ` Srinivas Pandruvada
2019-11-15 10:34 ` Giovanni Gherdovich
2019-11-13 12:46 ` [PATCH v4 6/6] x86: intel_pstate: handle runtime turbo disablement/enablement in freq. invariance Giovanni Gherdovich
2019-12-18 20:37 ` [PATCH v4 0/6] Add support for frequency invariance for (some) x86 Peter Zijlstra
2019-12-19 20:33 ` Giovanni Gherdovich
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