linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Giovanni Gherdovich <ggherdovich@suse.cz>
To: Quentin Perret <qperret@qperret.net>
Cc: srinivas.pandruvada@linux.intel.com, tglx@linutronix.de,
	mingo@redhat.com, peterz@infradead.org, bp@suse.de,
	lenb@kernel.org, rjw@rjwysocki.net, x86@kernel.org,
	linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
	mgorman@techsingularity.net, matt@codeblueprint.co.uk,
	viresh.kumar@linaro.org, juri.lelli@redhat.com, pjt@google.com,
	vincent.guittot@linaro.org, dietmar.eggemann@arm.com
Subject: Re: [PATCH 1/2] x86,sched: Add support for frequency invariance
Date: Tue, 17 Sep 2019 16:27:46 +0200	[thread overview]
Message-ID: <1568730466.3329.4.camel@suse.cz> (raw)
In-Reply-To: <20190914105708.GA12877@qperret.net>

Hello Quentin,

On Sat, 2019-09-14 at 12:57 +0200, Quentin Perret wrote:
> Hi Giovanni
> 
> On Monday 09 Sep 2019 at 04:42:15 (+0200), Giovanni Gherdovich wrote:
> > +static inline long arch_scale_freq_capacity(int cpu)
> > +{
> > +	if (static_cpu_has(X86_FEATURE_APERFMPERF))
> > +		return per_cpu(arch_cpu_freq, cpu);
> 
> So, if this is conditional, perhaps you could also add this check in an
> x86-specific implementation of arch_scale_freq_invariant() ? That would
> guide sugov in the right path (see get_next_freq()) if APERF/MPERF are
> unavailable.
> 
> > +	return 1024 /* SCHED_CAPACITY_SCALE */;
> > +}
>

Good remark. If the cpu doesn't have APERF/MPERF, the choice here is that
freq_curr is constantly equal to freq_max, and the scaling factor is 1 all the
time.

But I'm checking this static_cpu_has() every time I do a frequency update;
arguably schedutil should be smarter and settle such a case once and for all
at boot time.

I'll check what's the cost of static_cpu_has() and if it's non-negligible I'll
do what you suggest (x86-specific version of arch_scale_freq_invariant().


Giovanni

  reply	other threads:[~2019-09-17 14:22 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-09  2:42 [PATCH 0/2] Add support for frequency invariance for (some) x86 Giovanni Gherdovich
2019-09-09  2:42 ` [PATCH 1/2] x86,sched: Add support for frequency invariance Giovanni Gherdovich
2019-09-11 15:28   ` Doug Smythies
2019-09-13 20:58     ` Doug Smythies
2019-09-17 14:25       ` Giovanni Gherdovich
2019-09-19 14:42         ` Doug Smythies
2019-09-24  8:06           ` Mel Gorman
2019-09-24 17:52             ` Doug Smythies
2019-09-13 22:52   ` Srinivas Pandruvada
2019-09-17 14:27     ` Giovanni Gherdovich
2019-09-17 15:55       ` Vincent Guittot
2019-09-19 23:55       ` Srinivas Pandruvada
2019-09-14 10:57   ` Quentin Perret
2019-09-17 14:27     ` Giovanni Gherdovich [this message]
2019-09-17 14:39       ` Quentin Perret
2019-09-24 14:03       ` Peter Zijlstra
2019-09-24 16:00         ` Peter Zijlstra
2019-10-02 12:27           ` Giovanni Gherdovich
2019-10-02 18:45             ` Peter Zijlstra
2019-09-24 16:04   ` Peter Zijlstra
2019-10-02 12:26     ` Giovanni Gherdovich
2019-10-02 18:35       ` Peter Zijlstra
2019-09-24 16:30   ` Peter Zijlstra
2019-10-02 12:25     ` Giovanni Gherdovich
2019-10-02 18:47       ` Peter Zijlstra
2019-09-09  2:42 ` [PATCH 2/2] cpufreq: intel_pstate: Conditional frequency invariant accounting Giovanni Gherdovich
2019-09-24 16:01 ` [PATCH 0/2] Add support for frequency invariance for (some) x86 Peter Zijlstra

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1568730466.3329.4.camel@suse.cz \
    --to=ggherdovich@suse.cz \
    --cc=bp@suse.de \
    --cc=dietmar.eggemann@arm.com \
    --cc=juri.lelli@redhat.com \
    --cc=lenb@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pm@vger.kernel.org \
    --cc=matt@codeblueprint.co.uk \
    --cc=mgorman@techsingularity.net \
    --cc=mingo@redhat.com \
    --cc=peterz@infradead.org \
    --cc=pjt@google.com \
    --cc=qperret@qperret.net \
    --cc=rjw@rjwysocki.net \
    --cc=srinivas.pandruvada@linux.intel.com \
    --cc=tglx@linutronix.de \
    --cc=vincent.guittot@linaro.org \
    --cc=viresh.kumar@linaro.org \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).