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Groups > linux.kernel > #1520144
| From | Saravana Kannan <skannan@codeaurora.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 2/3] cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task |
| Date | 2016-11-12 02:40 +0100 |
| Message-ID | <sCvsu-3K4-9@gated-at.bofh.it> (permalink) |
| References | <sChfQ-35W-17@gated-at.bofh.it> <sChfQ-35W-19@gated-at.bofh.it> <sCskV-1Uz-11@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On 11/11/2016 02:16 PM, Rafael J. Wysocki wrote:
> On Fri, Nov 11, 2016 at 11:22 AM, Viresh Kumar <viresh.kumar@linaro.org> wrote:
>> If slow path frequency changes are conducted in a SCHED_OTHER context
>> then they may be delayed for some amount of time, including
>> indefinitely, when real time or deadline activity is taking place.
>>
>> Move the slow path to a real time kernel thread. In the future the
>> thread should be made SCHED_DEADLINE. The RT priority is arbitrarily set
>> to 50 for now.
>>
>> Hackbench results on ARM Exynos, dual core A15 platform for 10
>> iterations:
>>
>> $ hackbench -s 100 -l 100 -g 10 -f 20
>>
>> Before After
>> ---------------------------------
>> 1.808 1.603
>> 1.847 1.251
>> 2.229 1.590
>> 1.952 1.600
>> 1.947 1.257
>> 1.925 1.627
>> 2.694 1.620
>> 1.258 1.621
>> 1.919 1.632
>> 1.250 1.240
>>
>> Average:
>>
>> 1.8829 1.5041
>>
>> Based on initial work by Steve Muckle.
>>
>> Signed-off-by: Steve Muckle <smuckle.linux@gmail.com>
>> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
>> ---
>> kernel/sched/cpufreq_schedutil.c | 62 ++++++++++++++++++++++++++++++++--------
>> 1 file changed, 50 insertions(+), 12 deletions(-)
>>
>> diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
>> index ccb2ab89affb..045ce0a4e6d1 100644
>> --- a/kernel/sched/cpufreq_schedutil.c
>> +++ b/kernel/sched/cpufreq_schedutil.c
>> @@ -12,6 +12,7 @@
>> #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>>
>> #include <linux/cpufreq.h>
>> +#include <linux/kthread.h>
>> #include <linux/slab.h>
>> #include <trace/events/power.h>
>>
>> @@ -35,8 +36,10 @@ struct sugov_policy {
>>
>> /* The next fields are only needed if fast switch cannot be used. */
>> struct irq_work irq_work;
>> - struct work_struct work;
>> + struct kthread_work work;
>> struct mutex work_lock;
>> + struct kthread_worker worker;
>> + struct task_struct *thread;
>> bool work_in_progress;
>>
>> bool need_freq_update;
>> @@ -291,9 +294,10 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time,
>> raw_spin_unlock(&sg_policy->update_lock);
>> }
>>
>> -static void sugov_work(struct work_struct *work)
>> +static void sugov_work(struct kthread_work *work)
>> {
>> - struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work);
>> + struct sugov_policy *sg_policy =
>> + container_of(work, struct sugov_policy, work);
>
> Why this change?
>
>>
>> mutex_lock(&sg_policy->work_lock);
>> __cpufreq_driver_target(sg_policy->policy, sg_policy->next_freq,
>> @@ -308,7 +312,7 @@ static void sugov_irq_work(struct irq_work *irq_work)
>> struct sugov_policy *sg_policy;
>>
>> sg_policy = container_of(irq_work, struct sugov_policy, irq_work);
>> - schedule_work_on(smp_processor_id(), &sg_policy->work);
>> + kthread_queue_work(&sg_policy->worker, &sg_policy->work);
>> }
>>
>> /************************** sysfs interface ************************/
>> @@ -362,9 +366,23 @@ static struct kobj_type sugov_tunables_ktype = {
>>
>> static struct cpufreq_governor schedutil_gov;
>>
>> +static void sugov_policy_free(struct sugov_policy *sg_policy)
>> +{
>> + if (!sg_policy->policy->fast_switch_enabled) {
>> + kthread_flush_worker(&sg_policy->worker);
>> + kthread_stop(sg_policy->thread);
>> + }
>> +
>> + mutex_destroy(&sg_policy->work_lock);
>> + kfree(sg_policy);
>> +}
>> +
>> static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
>> {
>> struct sugov_policy *sg_policy;
>> + struct task_struct *thread;
>> + struct sched_param param = { .sched_priority = 50 };
>
> I'd define a symbol for the 50. It's just one extra line of code ...
>
Hold on a sec. I thought during LPC someone (Peter?) made a point that
when RT thread run, we should bump the frequency to max? So, schedutil
is going to trigger schedutil to bump up the frequency to max, right?
-Saravana
--
Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
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[PATCH 2/3] cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task Viresh Kumar <viresh.kumar@linaro.org> - 2016-11-11 11:30 +0100
Re: [PATCH 2/3] cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task Tommaso Cucinotta <tommaso.cucinotta@sssup.it> - 2016-11-11 15:40 +0100
Re: [PATCH 2/3] cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task Peter Zijlstra <peterz@infradead.org> - 2016-11-11 15:40 +0100
Re: [PATCH 2/3] cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task Viresh Kumar <viresh.kumar@linaro.org> - 2016-11-12 06:30 +0100
Re: [PATCH 2/3] cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task Peter Zijlstra <peterz@infradead.org> - 2016-11-14 10:30 +0100
Re: [PATCH 2/3] cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task Viresh Kumar <viresh.kumar@linaro.org> - 2016-11-14 11:30 +0100
Re: [PATCH 2/3] cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task Viresh Kumar <viresh.kumar@linaro.org> - 2016-11-12 06:30 +0100
Re: [PATCH 2/3] cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task "Rafael J. Wysocki" <rafael@kernel.org> - 2016-11-11 23:20 +0100
Re: [PATCH 2/3] cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task Saravana Kannan <skannan@codeaurora.org> - 2016-11-12 02:40 +0100
Re: [PATCH 2/3] cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task Viresh Kumar <viresh.kumar@linaro.org> - 2016-11-12 06:30 +0100
Re: [PATCH 2/3] cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task Viresh Kumar <viresh.kumar@linaro.org> - 2016-11-14 06:40 +0100
Re: [PATCH 2/3] cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task "Rafael J. Wysocki" <rafael@kernel.org> - 2016-11-13 15:40 +0100
Re: [PATCH 2/3] cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task Steve Muckle <smuckle.linux@gmail.com> - 2016-11-13 20:50 +0100
Re: [PATCH 2/3] cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task "Rafael J. Wysocki" <rafael@kernel.org> - 2016-11-13 23:50 +0100
Re: [PATCH 2/3] cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task Viresh Kumar <viresh.kumar@linaro.org> - 2016-11-14 07:40 +0100
Re: [PATCH 2/3] cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task Viresh Kumar <viresh.kumar@linaro.org> - 2016-11-12 06:30 +0100
Re: [PATCH 2/3] cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task Steve Muckle <smuckle.linux@gmail.com> - 2016-11-13 21:00 +0100
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