From: Juri Lelli <juri.lelli@arm.com>
To: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>,
Morten Rasmussen <morten.rasmussen@arm.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
LAK <linux-arm-kernel@lists.infradead.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Russell King - ARM Linux <linux@arm.linux.org.uk>,
Sudeep Holla <sudeep.holla@arm.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Mark Brown <broonie@kernel.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Viresh Kumar <viresh.kumar@linaro.org>
Subject: Re: [PATCH v3 2/6] drivers/cpufreq: implement init_cpu_capacity_default()
Date: Wed, 10 Feb 2016 14:25:24 +0000 [thread overview]
Message-ID: <20160210142524.GE11415@e106622-lin> (raw)
In-Reply-To: <56BA0BCA.6090903@arm.com>
On 09/02/16 15:54, Dietmar Eggemann wrote:
> On 05/02/16 09:30, Juri Lelli wrote:
> > On 04/02/16 16:46, Vincent Guittot wrote:
> >> On 4 February 2016 at 16:44, Vincent Guittot <vincent.guittot@linaro.org> wrote:
> >>> On 4 February 2016 at 15:13, Juri Lelli <juri.lelli@arm.com> wrote:
> >>>> On 04/02/16 13:35, Vincent Guittot wrote:
> >>>>> On 4 February 2016 at 13:16, Juri Lelli <juri.lelli@arm.com> wrote:
> >>>>>> Hi Vincent,
> >>>>>>
> >>>>>> On 04/02/16 13:03, Vincent Guittot wrote:
> >>>>>>> On 4 February 2016 at 10:36, Morten Rasmussen <morten.rasmussen@arm.com> wrote:
> >>>>>>>> On Wed, Feb 03, 2016 at 10:04:37PM +0100, Vincent Guittot wrote:
> >>>>>>>>> On 3 February 2016 at 12:59, Juri Lelli <juri.lelli@arm.com> wrote:
>
> [...]
>
> >>>
> >>> AFAICT, They don't have a dedicated cpufreq driver.
> >>>
> >>> More generally speaking, it can take time before having
> >>
> >> email sent before the ne d of the sentence ...
> >>
> >> More generally speaking, it can take time before having a cpufreq
> >> driver whereas we want to run and test scheduler behavior of these
> >> heterogenous platform
> >>
> >
> > I'm not familiar with this platform, but from what you are saying and
> > what I could find online, it looks like full Linux support is not
> > finished yet. Can we consider that as still in development? And if we
> > can do that, maybe is fair enough that we use the sysfs interface to
> > play with that platform until support is complete.
> >
> > Do others have any opinion on this point?
>
> IMHO, the solution should work for all of heterogeneous systems, (a) w/
> cpufreq and driver, (b) w/ cpufreq and no driver loaded (yet) or (c) w/o
> cpufreq.
>
> That means that you can't put the benchmarking only into
> cpufreq_register_driver() and rely on cpufreq policy topology.
>
> Maybe you could do this for (b) and (c) inside an initcall and use
> topology_core_cpumask() to figure out which cpu to profile?
>
> This would then happen w/ the cpu frequency set by the fw.
>
> But this then has to be synchronized somehow with the benchmarking
> approach in cpufreq_register_driver().
>
Yes, I guess the tricky situation is the mixed one, when we might have
the benchmarking executing in a late_initcall when cpufreq kicks in. Or
we can also end up doing the benchmarking twice if cpufreq finishes
initialization after the late_initcall has been executed.
I'm not sure how this can be solved in a clean way. Ideally we would
start benchmarking in the late_initcall (at the frequency set by fw) and
then bailout if cpufreq kicks in. That should work also for the cpufreq
driver as a module case. But, we could do the same thing twice if the
late_initcall is faster or gets executed before cpufreq starts to be
initialized.
Any suggestion anyone? :)
Best,
- Juri
next prev parent reply other threads:[~2016-02-10 14:24 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-03 11:59 [PATCH v3 0/6] CPUs capacity information for heterogeneous systems Juri Lelli
2016-02-03 11:59 ` [PATCH v3 1/6] ARM: initialize cpu_scale to its default Juri Lelli
2016-02-03 11:59 ` [PATCH v3 2/6] drivers/cpufreq: implement init_cpu_capacity_default() Juri Lelli
2016-02-03 21:04 ` Vincent Guittot
2016-02-04 9:36 ` Morten Rasmussen
2016-02-04 12:03 ` Vincent Guittot
2016-02-04 12:16 ` Juri Lelli
2016-02-04 12:35 ` Vincent Guittot
2016-02-04 14:13 ` Juri Lelli
2016-02-04 15:44 ` Vincent Guittot
2016-02-04 15:46 ` Vincent Guittot
2016-02-05 9:30 ` Juri Lelli
2016-02-09 15:54 ` Dietmar Eggemann
2016-02-10 14:25 ` Juri Lelli [this message]
2016-02-03 11:59 ` [PATCH v3 3/6] arm: Enable dynamic CPU capacity initialization Juri Lelli
2016-02-03 11:59 ` [PATCH v3 4/6] arm64: " Juri Lelli
2016-02-08 12:28 ` Dietmar Eggemann
2016-02-08 13:13 ` Mark Brown
2016-02-08 13:41 ` Dietmar Eggemann
2016-02-03 11:59 ` [PATCH v3 5/6] arm: add sysfs cpu_capacity attribute Juri Lelli
2016-02-03 11:59 ` [PATCH v3 6/6] arm64: " Juri Lelli
2016-02-05 17:19 ` Dietmar Eggemann
2016-02-05 17:49 ` Juri Lelli
2016-02-08 23:59 ` [PATCH v3 0/6] CPUs capacity information for heterogeneous systems Steve Muckle
2016-02-09 10:37 ` Juri Lelli
2016-02-09 17:30 ` Steve Muckle
2016-02-09 17:40 ` Juri Lelli
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