Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: [PATCH V2 3/9] cpufreq: ondemand: only queue canceled works from update_sampling_rate() | Date | Tue, 08 Sep 2015 03:11:49 +0200 |
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On Monday, July 27, 2015 05:58:08 PM Viresh Kumar wrote: > The sampling rate is updated with a call to update_sampling_rate(), and > we process CPUs one by one here. While the work is canceled on per-cpu > basis, it is getting queued (by mistake) for all policy->cpus. > > This would result in wasting cpu cycles for queuing works which are > already queued and never canceled. > > This patch changes this behavior to queue work only on the cpu, for > which it was canceled earlier. > > To do that, replace 'modify_all' parameter to gov_queue_work() with a > mask of CPUs.
There really are two cases, either you pass a CPU or gov_queue_work() has to walk policy->cpus. Doing it the way you did hides that IMO.
I'd simply pass an int and use a special value to indicate that policy->cpus is to be walked.
> Also the last parameter to ->gov_dbs_timer() was named > 'modify_all' earlier, but its purpose was to decide if load has to be > evaluated again or not. Lets rename that to load_eval. > > Fixes: 031299b3be30 ("cpufreq: governors: Avoid unnecessary per cpu timer interrupts") > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> > --- > drivers/cpufreq/cpufreq_conservative.c | 4 ++-- > drivers/cpufreq/cpufreq_governor.c | 30 ++++++++++-------------------- > drivers/cpufreq/cpufreq_governor.h | 4 ++-- > drivers/cpufreq/cpufreq_ondemand.c | 7 ++++--- > 4 files changed, 18 insertions(+), 27 deletions(-) > > diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c > index 18bfbc313e48..1aa3bd46cea3 100644 > --- a/drivers/cpufreq/cpufreq_conservative.c > +++ b/drivers/cpufreq/cpufreq_conservative.c > @@ -116,11 +116,11 @@ static void cs_check_cpu(int cpu, unsigned int load) > } > > static unsigned int cs_dbs_timer(struct cpu_dbs_info *cdbs, > - struct dbs_data *dbs_data, bool modify_all) > + struct dbs_data *dbs_data, bool load_eval) > { > struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; > > - if (modify_all) > + if (load_eval) > dbs_check_cpu(dbs_data, cdbs->shared->policy->cpu); > > return delay_for_sampling_rate(cs_tuners->sampling_rate); > diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c > index 750626d8fb03..a890450711bb 100644 > --- a/drivers/cpufreq/cpufreq_governor.c > +++ b/drivers/cpufreq/cpufreq_governor.c > @@ -167,7 +167,7 @@ static inline void __gov_queue_work(int cpu, struct dbs_data *dbs_data, > } > > void gov_queue_work(struct dbs_data *dbs_data, struct cpufreq_policy *policy, > - unsigned int delay, bool all_cpus) > + unsigned int delay, const struct cpumask *cpus) > { > int i; > > @@ -175,19 +175,8 @@ void gov_queue_work(struct dbs_data *dbs_data, struct cpufreq_policy *policy, > if (!policy->governor_enabled) > goto out_unlock; > > - if (!all_cpus) { > - /* > - * Use raw_smp_processor_id() to avoid preemptible warnings. > - * We know that this is only called with all_cpus == false from > - * works that have been queued with *_work_on() functions and > - * those works are canceled during CPU_DOWN_PREPARE so they > - * can't possibly run on any other CPU. > - */
This was a useful comment and it should be moved along the logic it was supposed to explain and not just dropped.
> - __gov_queue_work(raw_smp_processor_id(), dbs_data, delay); > - } else { > - for_each_cpu(i, policy->cpus) > - __gov_queue_work(i, dbs_data, delay); > - } > + for_each_cpu(i, cpus) > + __gov_queue_work(i, dbs_data, delay); > > out_unlock: > mutex_unlock(&cpufreq_governor_lock); > @@ -232,7 +221,8 @@ static void dbs_timer(struct work_struct *work) > struct cpufreq_policy *policy = shared->policy; > struct dbs_data *dbs_data = policy->governor_data; > unsigned int sampling_rate, delay; > - bool modify_all = true; > + const struct cpumask *cpus;
I don't think this local variable is necessary.
> + bool load_eval; > > mutex_lock(&shared->timer_mutex); > > @@ -246,11 +236,11 @@ static void dbs_timer(struct work_struct *work) > sampling_rate = od_tuners->sampling_rate; > } > > - if (!need_load_eval(cdbs->shared, sampling_rate)) > - modify_all = false; > + load_eval = need_load_eval(cdbs->shared, sampling_rate); > + cpus = load_eval ? policy->cpus : cpumask_of(raw_smp_processor_id()); > > - delay = dbs_data->cdata->gov_dbs_timer(cdbs, dbs_data, modify_all); > - gov_queue_work(dbs_data, policy, delay, modify_all); > + delay = dbs_data->cdata->gov_dbs_timer(cdbs, dbs_data, load_eval); > + gov_queue_work(dbs_data, policy, delay, cpus); > > mutex_unlock(&shared->timer_mutex); > } > @@ -474,7 +464,7 @@ static int cpufreq_governor_start(struct cpufreq_policy *policy, > } > > gov_queue_work(dbs_data, policy, delay_for_sampling_rate(sampling_rate), > - true); > + policy->cpus); > return 0; > } > > diff --git a/drivers/cpufreq/cpufreq_governor.h b/drivers/cpufreq/cpufreq_governor.h > index 5621bb03e874..52665a0624b2 100644 > --- a/drivers/cpufreq/cpufreq_governor.h > +++ b/drivers/cpufreq/cpufreq_governor.h > @@ -211,7 +211,7 @@ struct common_dbs_data { > void *(*get_cpu_dbs_info_s)(int cpu); > unsigned int (*gov_dbs_timer)(struct cpu_dbs_info *cdbs, > struct dbs_data *dbs_data, > - bool modify_all); > + bool load_eval); > void (*gov_check_cpu)(int cpu, unsigned int load); > int (*init)(struct dbs_data *dbs_data, bool notify); > void (*exit)(struct dbs_data *dbs_data, bool notify); > @@ -273,7 +273,7 @@ void dbs_check_cpu(struct dbs_data *dbs_data, int cpu); > int cpufreq_governor_dbs(struct cpufreq_policy *policy, > struct common_dbs_data *cdata, unsigned int event); > void gov_queue_work(struct dbs_data *dbs_data, struct cpufreq_policy *policy, > - unsigned int delay, bool all_cpus); > + unsigned int delay, const struct cpumask *cpus); > void od_register_powersave_bias_handler(unsigned int (*f) > (struct cpufreq_policy *, unsigned int, unsigned int), > unsigned int powersave_bias); > diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c > index 1fa9088c84a8..2474c9c34022 100644 > --- a/drivers/cpufreq/cpufreq_ondemand.c > +++ b/drivers/cpufreq/cpufreq_ondemand.c > @@ -192,7 +192,7 @@ static void od_check_cpu(int cpu, unsigned int load) > } > > static unsigned int od_dbs_timer(struct cpu_dbs_info *cdbs, > - struct dbs_data *dbs_data, bool modify_all) > + struct dbs_data *dbs_data, bool load_eval) > { > struct cpufreq_policy *policy = cdbs->shared->policy; > unsigned int cpu = policy->cpu; > @@ -201,7 +201,7 @@ static unsigned int od_dbs_timer(struct cpu_dbs_info *cdbs, > struct od_dbs_tuners *od_tuners = dbs_data->tuners; > int delay = 0, sample_type = dbs_info->sample_type; > > - if (!modify_all) > + if (!load_eval) > goto max_delay; > > /* Common NORMAL_SAMPLE setup */ > @@ -284,7 +284,8 @@ static void update_sampling_rate(struct dbs_data *dbs_data, > mutex_lock(&dbs_info->cdbs.shared->timer_mutex); > > gov_queue_work(dbs_data, policy, > - usecs_to_jiffies(new_rate), true); > + usecs_to_jiffies(new_rate), > + cpumask_of(cpu)); > > } > mutex_unlock(&dbs_info->cdbs.shared->timer_mutex); >
Thanks, Rafael
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