From: Dominik Brodowski <linux@dominikbrodowski.net>
To: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>,
Rafael Wysocki <rjw@rjwysocki.net>,
Linux PM <linux-pm@vger.kernel.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [RFC V2 1/6] cpufreq: Replace "max_transition_latency" with "dynamic_switching"
Date: Fri, 14 Jul 2017 09:01:42 +0200 [thread overview]
Message-ID: <20170714070142.GA14515@isilmar-4.linta.de> (raw)
In-Reply-To: <CAJZ5v0g-DgV6G-J9pkAYKooqgbJDV_ML8cR8wquKksN=x_JpoQ@mail.gmail.com>
On Thu, Jul 13, 2017 at 06:19:53PM +0200, Rafael J. Wysocki wrote:
> On Thu, Jul 13, 2017 at 7:40 AM, Viresh Kumar <viresh.kumar@linaro.org> wrote:
> > There is no limitation in the ondemand or conservative governors which
> > disallow the transition_latency to be greater than 10 ms.
> >
> > The max_transition_latency field is rather used to disallow automatic
> > dynamic frequency switching for platforms which didn't wanted these
> > governors to run.
> >
> > Replace max_transition_latency with a boolean (dynamic_switching) and
> > check for transition_latency == CPUFREQ_ETERNAL along with that. This
> > makes it pretty straight forward to read/understand now.
>
> Well, using CPUFREQ_ETERNAL for that on the driver side is still not
> particularly straightforward IMO, so maybe add a
> "no_dynamic_switching" to the driver structure and set it to "true"
> for the one driver in question?
IIRC it's not just one driver which sets the latency to CPUFREQ_ETERNAL, and
where dynamic switching might be harmful or at least lead to undefined
behavior.
Best,
Dominik
next prev parent reply other threads:[~2017-07-14 7:01 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-13 5:40 [RFC V2 0/6] cpufreq: transition-latency cleanups Viresh Kumar
2017-07-13 5:40 ` [RFC V2 1/6] cpufreq: Replace "max_transition_latency" with "dynamic_switching" Viresh Kumar
2017-07-13 16:19 ` Rafael J. Wysocki
2017-07-14 7:01 ` Dominik Brodowski [this message]
2017-07-14 11:11 ` Rafael J. Wysocki
2017-07-14 22:06 ` Rafael J. Wysocki
2017-07-15 5:08 ` Dominik Brodowski
2017-07-15 12:26 ` Rafael J. Wysocki
2017-07-17 11:58 ` Viresh Kumar
2017-07-17 12:18 ` Rafael J. Wysocki
2017-07-13 5:40 ` [RFC V2 2/6] cpufreq: schedutil: Set dynamic_switching to true Viresh Kumar
2017-07-13 5:40 ` [RFC V2 3/6] cpufreq: governor: Drop min_sampling_rate Viresh Kumar
2017-07-13 5:40 ` [RFC V2 4/6] cpufreq: Use transition_delay_us for legacy governors as well Viresh Kumar
2017-07-13 16:31 ` Rafael J. Wysocki
2017-07-13 5:40 ` [RFC V2 5/6] cpufreq: Cap the default transition delay value to 10 ms Viresh Kumar
2017-07-13 5:40 ` [RFC V2 6/6] cpufreq: arm_big_little: Make ->get_transition_latency() mandatory Viresh Kumar
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