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Message-ID: <597902DA.8060608@codeaurora.org>
Date: Wed, 26 Jul 2017 14:00:10 -0700
From: Saravana Kannan <skannan@...eaurora.org>
To: Peter Zijlstra <peterz@...radead.org>
CC: Viresh Kumar <viresh.kumar@...aro.org>, linux-pm@...r.kernel.org,
Rafael Wysocki <rjw@...ysocki.net>,
linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
eas-dev@...ts.linaro.org, smuckle.linux@...il.com,
Len Brown <lenb@...nel.org>
Subject: Re: [Eas-dev] [PATCH V3 1/3] sched: cpufreq: Allow remote cpufreq
callbacks
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.
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