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Re: [PATCH v3 9/10] cpufreq: sched: Re-introduce cpufreq_update_util()

From "Rafael J. Wysocki" <rafael@kernel.org>
Newsgroups linux.kernel
Subject Re: [PATCH v3 9/10] cpufreq: sched: Re-introduce cpufreq_update_util()
Date 2016-03-04 22:40 +0100
Message-ID <r95C2-4Cy-27@gated-at.bofh.it> (permalink)
References (1 earlier) <r8OKR-B1-3@gated-at.bofh.it> <r8OKS-B1-19@gated-at.bofh.it> <r8XXQ-7oV-3@gated-at.bofh.it> <r95sm-4wI-11@gated-at.bofh.it> <r95sn-4wI-39@gated-at.bofh.it>
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On Fri, Mar 4, 2016 at 10:27 PM, Rafael J. Wysocki <rafael@kernel.org> wrote:
> On Fri, Mar 4, 2016 at 10:21 PM, Steve Muckle <steve.muckle@linaro.org> wrote:
>> On 03/04/2016 05:30 AM, Rafael J. Wysocki wrote:
>>> +void cpufreq_update_util(u64 time, unsigned long util, unsigned long max)
>>> +{
>>> +     struct freq_update_hook *hook;
>>> +
>>> +#ifdef CONFIG_LOCKDEP
>>> +     WARN_ON(debug_locks && !rcu_read_lock_sched_held());
>>> +#endif
>>> +
>>> +     hook = rcu_dereference_sched(*this_cpu_ptr(&cpufreq_freq_update_hook));
>>> +     /*
>>> +      * If this isn't inside of an RCU-sched read-side critical section, hook
>>> +      * may become NULL after the check below.
>>> +      */
>>> +     if (hook) {
>>> +             if (hook->update_util)
>>> +                     hook->update_util(hook, time, util, max);
>>> +             else
>>> +                     hook->func(hook, time);
>>> +     }
>>
>> Is it worth having two hook types?
>
> Well, that's why I said "maybe over the top" in the changelog comments. :-)
>
> If we want to isolate the "old" governors from util/max entirely, then yes.
>
> If we don't care that much, then no.
>
> I'm open to both possibilities.

But in the latter case I don't see a particular reason to put the new
governor under kernel/sched/ too and as I wrote in the changelog
comments to patch [10/10], I personally think that it would be cleaner
to keep it under drivers/cpufreq/.

Thanks,
Rafael

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[PATCH v3 9/10] cpufreq: sched: Re-introduce cpufreq_update_util() "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-03-04 14:30 +0100
  Re: [PATCH v3 9/10] cpufreq: sched: Re-introduce  cpufreq_update_util() Steve Muckle <steve.muckle@linaro.org> - 2016-03-04 22:30 +0100
    Re: [PATCH v3 9/10] cpufreq: sched: Re-introduce cpufreq_update_util() "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-04 22:30 +0100
      Re: [PATCH v3 9/10] cpufreq: sched: Re-introduce cpufreq_update_util() "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-04 22:40 +0100

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