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Re: [Eas-dev] [PATCH V3 1/3] sched: cpufreq: Allow remote cpufreq callbacks

From Saravana Kannan <skannan@codeaurora.org>
Newsgroups linux.kernel
Subject Re: [Eas-dev] [PATCH V3 1/3] sched: cpufreq: Allow remote cpufreq callbacks
Date 2017-07-26 23:10 +0200
Message-ID <u7BJ8-5vg-19@gated-at.bofh.it> (permalink)
References <u2G6J-2a4-3@gated-at.bofh.it> <u2G6K-2a4-17@gated-at.bofh.it> <u5FQR-5ft-1@gated-at.bofh.it>
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On 07/21/2017 06:03 AM, Peter Zijlstra wrote:
> On Thu, Jul 13, 2017 at 12:14:37PM +0530, Viresh Kumar wrote:
>> diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
>> index 47e24b5384b3..606b1a37a1af 100644
>> --- a/drivers/cpufreq/cpufreq_governor.c
>> +++ b/drivers/cpufreq/cpufreq_governor.c
>> @@ -275,6 +275,10 @@ static void dbs_update_util_handler(struct update_util_data *data, u64 time,
>>   	struct policy_dbs_info *policy_dbs = cdbs->policy_dbs;
>>   	u64 delta_ns, lst;
>>
>> +	/* Don't allow remote callbacks */
>> +	if (smp_processor_id() != data->cpu)
>> +		return;
>> +
>
> The alternative is using some of that policy_dbs->policy->*cpus crud I
> suppose, because:

No, the alternative is to pass it on to the CPU freq driver and let it 
decide what it wants to do. That's the whole point if having a CPU freq 
driver -- so that the generic code doesn't need to care about HW 
specific details. Which is the point I was making in an earlier email to 
Viresh's patch -- we shouldn't be doing any CPU check for the call backs 
at the scheduler or ever governor level.

That would simplify this whole thing by deleting a bunch of code. And 
having much simpler checks in those drivers that actually have to deal 
with their HW specific details.


-- 
Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

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Re: [PATCH V3 1/3] sched: cpufreq: Allow remote cpufreq callbacks Peter Zijlstra <peterz@infradead.org> - 2017-07-21 15:10 +0200
  Re: [PATCH V3 1/3] sched: cpufreq: Allow remote cpufreq callbacks Viresh Kumar <viresh.kumar@linaro.org> - 2017-07-24 13:10 +0200
    Re: [PATCH V3 1/3] sched: cpufreq: Allow remote cpufreq callbacks Peter Zijlstra <peterz@infradead.org> - 2017-07-24 15:50 +0200
      Re: [PATCH V3 1/3] sched: cpufreq: Allow remote cpufreq callbacks Viresh Kumar <viresh.kumar@linaro.org> - 2017-07-26 08:30 +0200
        Re: [PATCH V3 1/3] sched: cpufreq: Allow remote cpufreq callbacks Peter Zijlstra <peterz@infradead.org> - 2017-07-26 10:20 +0200
        Re: [PATCH V3 1/3] sched: cpufreq: Allow remote cpufreq callbacks "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2017-07-26 19:40 +0200
  Re: [Eas-dev] [PATCH V3 1/3] sched: cpufreq: Allow remote cpufreq  callbacks Saravana Kannan <skannan@codeaurora.org> - 2017-07-26 23:10 +0200
    Re: [Eas-dev] [PATCH V3 1/3] sched: cpufreq: Allow remote cpufreq  callbacks Viresh Kumar <viresh.kumar@linaro.org> - 2017-07-27 05:40 +0200
      Re: [Eas-dev] [PATCH V3 1/3] sched: cpufreq: Allow remote cpufreq  callbacks Saravana Kannan <skannan@codeaurora.org> - 2017-07-27 22:00 +0200
        Re: [Eas-dev] [PATCH V3 1/3] sched: cpufreq: Allow remote cpufreq callbacks "Joel Fernandes (Google)" <joel.opensrc@gmail.com> - 2017-07-28 06:40 +0200
        Re: [Eas-dev] [PATCH V3 1/3] sched: cpufreq: Allow remote cpufreq  callbacks Viresh Kumar <viresh.kumar@linaro.org> - 2017-07-28 08:10 +0200
          Re: [Eas-dev] [PATCH V3 1/3] sched: cpufreq: Allow remote cpufreq  callbacks Saravana Kannan <skannan@codeaurora.org> - 2017-07-28 23:10 +0200
            Re: [Eas-dev] [PATCH V3 1/3] sched: cpufreq: Allow remote cpufreq  callbacks Viresh Kumar <viresh.kumar@linaro.org> - 2017-07-31 06:00 +0200

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