Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: [PATCH V2 6/9] cpufreq: ondemand: queue work for policy->cpus together | Date | Tue, 08 Sep 2015 03:33:45 +0200 |
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On Monday, July 27, 2015 05:58:11 PM Viresh Kumar wrote: > Currently update_sampling_rate() runs over each online CPU and > cancels/queues work on it. Its very inefficient for the case where a > single policy manages multiple CPUs, as they can be processed together. > > Also drop the unnecessary cancel_delayed_work_sync() as we are doing a > mod_delayed_work_on() in gov_queue_work(), which will take care of > pending works for us. > > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> > --- > drivers/cpufreq/cpufreq_ondemand.c | 31 ++++++++++++++++++------------- > 1 file changed, 18 insertions(+), 13 deletions(-) > > diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c > index f1551fc7b4fd..a6f579e40ce2 100644 > --- a/drivers/cpufreq/cpufreq_ondemand.c > +++ b/drivers/cpufreq/cpufreq_ondemand.c > @@ -247,40 +247,45 @@ static void update_sampling_rate(struct dbs_data *dbs_data, > unsigned int new_rate) > { > struct od_dbs_tuners *od_tuners = dbs_data->tuners; > + struct cpufreq_policy *policy; > + struct od_cpu_dbs_info_s *dbs_info; > + unsigned long next_sampling, appointed_at; > + struct cpumask cpumask; > int cpu; > > + cpumask_copy(&cpumask, cpu_online_mask); > + > od_tuners->sampling_rate = new_rate = max(new_rate, > dbs_data->min_sampling_rate); > > - for_each_online_cpu(cpu) { > - struct cpufreq_policy *policy; > - struct od_cpu_dbs_info_s *dbs_info; > - unsigned long next_sampling, appointed_at; > - > + for_each_cpu(cpu, &cpumask) { > policy = cpufreq_cpu_get(cpu); > if (!policy) > continue; > + > + /* clear all CPUs of this policy */ > + cpumask_andnot(&cpumask, &cpumask, policy->cpus);
Well, this is not exactly straightforward, but should work.
> + > if (policy->governor != &cpufreq_gov_ondemand) { > cpufreq_cpu_put(policy); > continue; > } > + > dbs_info = &per_cpu(od_cpu_dbs_info, cpu); > cpufreq_cpu_put(policy); > > - if (!delayed_work_pending(&dbs_info->cdbs.dwork)) > + /* Make sure the work is not canceled on policy->cpus */
I'm not sure what scenario can lead to that. Care to explain?
> + if (!dbs_info->cdbs.shared->policy) > continue; > > next_sampling = jiffies + usecs_to_jiffies(new_rate); > appointed_at = dbs_info->cdbs.dwork.timer.expires;
For that to work we always need to do stuff for policy->cpus in sync. Do we?
> - if (time_before(next_sampling, appointed_at)) { > - cancel_delayed_work_sync(&dbs_info->cdbs.dwork); > - > - gov_queue_work(dbs_data, policy, > - usecs_to_jiffies(new_rate), > - cpumask_of(cpu)); > + if (!time_before(next_sampling, appointed_at)) > + continue; > > - } > + gov_queue_work(dbs_data, policy, usecs_to_jiffies(new_rate), > + policy->cpus); > } > } > >
Thanks, Rafael
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