On 06/22/2015 01:32 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.
This looks fine, except for one point. See below:
Signed-off-by: Viresh Kumar viresh.kumar@linaro.org
drivers/cpufreq/cpufreq_ondemand.c | 32 ++++++++++++++++++++------------ 1 file changed, 20 insertions(+), 12 deletions(-)
diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c index 841e1fa96ee7..cfecd3b67cb3 100644 --- a/drivers/cpufreq/cpufreq_ondemand.c +++ b/drivers/cpufreq/cpufreq_ondemand.c @@ -247,40 +247,48 @@ 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);if (policy->governor != &cpufreq_gov_ondemand) { cpufreq_cpu_put(policy); continue; }
dbs_info = &per_cpu(od_cpu_dbs_info, cpu); cpufreq_cpu_put(policy);
/** Checking this for any CPU of the policy is fine. As either* all would have queued work or none.
Are you sure that the state of the work will be the same across all policy cpus ? 'Pending' only refers to twork awaiting for the timer to fire and then queue itself on the runqueue right ? On some of the policy->cpus, timers may be yet to fire, while on others it might already have ?
*/if (!delayed_work_pending(&dbs_info->cdbs.dwork)) continue;
next_sampling = jiffies + usecs_to_jiffies(new_rate); appointed_at = dbs_info->cdbs.dwork.timer.expires;
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);}
Regards Preeti U Murthy