From: Juri Lelli <juri.lelli@arm.com>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: 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>,
Dietmar Eggemann <dietmar.eggemann@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: Thu, 4 Feb 2016 12:16:20 +0000 [thread overview]
Message-ID: <20160204121620.GB29586@e106622-lin> (raw)
In-Reply-To: <CAKfTPtB4G3bP5N0hU6zWXJTddO34x3RnyGpp-4_otc8O=Wq2hw@mail.gmail.com>
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:
>
> [snip]
>
> >> > diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
> >> > index 9e63fb1..c4025fd 100644
> >> > --- a/drivers/cpufreq/Makefile
> >> > +++ b/drivers/cpufreq/Makefile
> >> > @@ -1,5 +1,5 @@
> >> > # CPUfreq core
> >> > -obj-$(CONFIG_CPU_FREQ) += cpufreq.o freq_table.o
> >> > +obj-$(CONFIG_CPU_FREQ) += cpufreq.o freq_table.o cpufreq_capacity.o
> >>
> >> Do you really want to have the calibration of capacity dependent of
> >> cpufreq ? It means that we can't use it without a cpufreq driver.
> >> IMHO, this creates a unnecessary dependency. I understand that you
> >> must ensure that core runs at max fequency if a driver is present but
> >> you should be able to calibrate the capacity if cpufreq is not
> >> available but you have different capacity because micro architecture
> >
> > We could remove the dependency on cpufreq, but it would make things more
> > complicated for systems which do have frequency scaling as we would have
> > to either:
> >
> > 1) Run the calibration again once cpufreq has been initialized.
>
> or wait and let time for a driver to initialize and trig the
> calibration. If calibration has not been done at the end of the boot,
> you can force a calibration. If the cpufeq driver is a module and is
> loaded far later for any good or bad reason, we will have to run the
> calibration once again but at least the capacity will reflect he
> current capacity of the CPUs.
> I'm mainly worried that the compilation of the calibration is
> dependent of CONFIG_CPU_FREQ not that cpufreq can trig the calibration
> sequence
>
Yes, I guess we can make this work in some way. Out of curiosity,
though, are out there heterogenous platforms that don't use cpufreq?
I mean, I wouldn't add code and complexity from start, if there are not
good reasons to do so.
Thanks,
- Juri
next prev parent reply other threads:[~2016-02-04 12:15 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 [this message]
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
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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