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Date: Wed, 30 Mar 2016 18:44:00 -0700 From: Steve Muckle <steve.muckle@...aro.org> To: "Rafael J. Wysocki" <rafael@...nel.org> Cc: Viresh Kumar <viresh.kumar@...aro.org>, "Rafael J. Wysocki" <rjw@...ysocki.net>, Linux PM list <linux-pm@...r.kernel.org>, Juri Lelli <juri.lelli@....com>, ACPI Devel Maling List <linux-acpi@...r.kernel.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Peter Zijlstra <peterz@...radead.org>, Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>, Vincent Guittot <vincent.guittot@...aro.org>, Michael Turquette <mturquette@...libre.com>, Ingo Molnar <mingo@...nel.org> Subject: Re: [Update][PATCH v7 7/7] cpufreq: schedutil: New governor based on scheduler utilization data On 03/30/2016 10:24 AM, Rafael J. Wysocki wrote: > On Wed, Mar 30, 2016 at 7:05 PM, Steve Muckle <steve.muckle@...aro.org> wrote: >> On 03/30/2016 04:31 AM, Rafael J. Wysocki wrote: >>>>>>> +static int sugov_limits(struct cpufreq_policy *policy) >>>>>>> +{ >>>>>>> + struct sugov_policy *sg_policy = policy->governor_data; >>>>>>> + >>>>>>> + if (!policy->fast_switch_enabled) { >>>>>>> + mutex_lock(&sg_policy->work_lock); >>>>>>> + >>>>>>> + if (policy->max < policy->cur) >>>>>>> + __cpufreq_driver_target(policy, policy->max, >>>>>>> + CPUFREQ_RELATION_H); >>>>>>> + else if (policy->min > policy->cur) >>>>>>> + __cpufreq_driver_target(policy, policy->min, >>>>>>> + CPUFREQ_RELATION_L); >>>>>>> + >>>>>>> + mutex_unlock(&sg_policy->work_lock); >>>>>>> + } >>>>>>> + >>>>>>> + sg_policy->need_freq_update = true; >>>>> >>>>> I am wondering why we need to do this for !fast_switch_enabled case? >>> >>> That will cause the rate limit to be ignored in the utilization update >>> handler which may be necessary if it is set to a relatively large >>> value (like 1 s). >> >> But why is that necessary for !fast_switch_enabled? In that case the >> frequency has been adjusted to satisfy the new limits here, so ignoring >> the rate limit shouldn't be necessary. In other words why not >> >> } else { >> sg_policy->need_freq_update = true; >> } > > My thinking here was that the governor might decide to use something > different from the limit enforced here, so it would be good to make it > do so as soon as possible. In particular in the > non-frequency-invariant utilization case in which new frequency > depends on the current one. > > That said i'm not particularly opposed to making that change if that's > preferred. Ah ok fair enough. No strong opinion from me... thanks, Steve
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