Re: [PATCH] cpufreq: governor: Always schedule work on the CPU running update

From: Viresh Kumar
Date: Mon Mar 21 2016 - 22:51:21 EST


On 22-03-16, 01:17, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>
> Modify dbs_irq_work() to always schedule the process-context work
> on the current CPU which also ran the dbs_update_util_handler()
> that the irq_work being handled came from.
>
> This causes the entire frequency update handling (involving the
> "ondemand" or "conservative" governors) to be carried out by the
> CPU whose frequency is to be updated and reduces the overall amount
> of inter-CPU noise related to cpufreq.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
> drivers/cpufreq/cpufreq_governor.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> Index: linux-pm/drivers/cpufreq/cpufreq_governor.c
> ===================================================================
> --- linux-pm.orig/drivers/cpufreq/cpufreq_governor.c
> +++ linux-pm/drivers/cpufreq/cpufreq_governor.c
> @@ -245,7 +245,7 @@ static void dbs_irq_work(struct irq_work
> struct policy_dbs_info *policy_dbs;
>
> policy_dbs = container_of(irq_work, struct policy_dbs_info, irq_work);
> - schedule_work(&policy_dbs->work);
> + schedule_work_on(smp_processor_id(), &policy_dbs->work);
> }
>
> static void dbs_update_util_handler(struct update_util_data *data, u64 time,

queue_work() used to queue the work on local cpu by default, has that
changed now ?

--
viresh