| Message ID | 20240717063321.629-1-pugaowei@oppo.com |
|---|---|
| State | New |
| Headers | show |
| Series | cpufreq: queue policy->update work to rt thread to reduce its schedule latency | expand |
On Wed, 2024-07-17 at 14:33 +0800, Gaowei Pu wrote: > Currently we encountered a problem that the cpufreq boost latency > is about 10 milliseconds or worse when we boost through cpufreq QOS request > under high workload scenarios, while the boost latency mainly consumed by > schedule latency of policy->update work. What is the tail latency now after your change? > > We should ensure the low schedule latency of cpu frequency limits work > to meet performance and power demands. so queue the policy->update work > to rt thread to reduce its schedule latency. If my understanding is correct, kthread has a default nice value of 0 and is not a rt thread. I think the gain you see is your patch created a dedicated kthread work queue on CPU 0. The work from policy change no longer have to compete time with other requests coming from schedule_work(). If the policy change really needs to get ahead of other tasks, I think you need a dedicated workqueue with alloc_workqueue() using WQ_HIGHPRI flag. Tim > > Signed-off-by: Gaowei Pu <pugaowei@oppo.com> > --- > drivers/cpufreq/cpufreq.c | 24 ++++++++++++++++++------ > include/linux/cpufreq.h | 4 +++- > 2 files changed, 21 insertions(+), 7 deletions(-) > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index a45aac17c20f..e6e42a3ba9ab 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -1193,7 +1193,7 @@ void refresh_frequency_limits(struct cpufreq_policy *policy) > } > EXPORT_SYMBOL(refresh_frequency_limits); > > -static void handle_update(struct work_struct *work) > +static void handle_update(struct kthread_work *work) > { > struct cpufreq_policy *policy = > container_of(work, struct cpufreq_policy, update); > @@ -1209,7 +1209,7 @@ static int cpufreq_notifier_min(struct notifier_block *nb, unsigned long freq, > { > struct cpufreq_policy *policy = container_of(nb, struct cpufreq_policy, nb_min); > > - schedule_work(&policy->update); > + kthread_queue_work(policy->worker, &policy->update); > return 0; > } > > @@ -1218,7 +1218,7 @@ static int cpufreq_notifier_max(struct notifier_block *nb, unsigned long freq, > { > struct cpufreq_policy *policy = container_of(nb, struct cpufreq_policy, nb_max); > > - schedule_work(&policy->update); > + kthread_queue_work(policy->worker, &policy->update); > return 0; > } > > @@ -1301,15 +1301,25 @@ static struct cpufreq_policy *cpufreq_policy_alloc(unsigned int cpu) > goto err_min_qos_notifier; > } > > + policy->worker = kthread_create_worker_on_cpu(cpu, 0, "policy_worker%d", cpu); > + if (IS_ERR(policy->worker)) { > + dev_err(dev, "Failed to create policy_worker%d\n", cpu); > + goto err_max_qos_notifier; > + } > + > + sched_set_fifo_low(policy->worker->task); > INIT_LIST_HEAD(&policy->policy_list); > init_rwsem(&policy->rwsem); > spin_lock_init(&policy->transition_lock); > init_waitqueue_head(&policy->transition_wait); > - INIT_WORK(&policy->update, handle_update); > + kthread_init_work(&policy->update, handle_update); > > policy->cpu = cpu; > return policy; > > +err_max_qos_notifier: > + freq_qos_remove_notifier(&policy->constraints, FREQ_QOS_MAX, > + &policy->nb_max); > err_min_qos_notifier: > freq_qos_remove_notifier(&policy->constraints, FREQ_QOS_MIN, > &policy->nb_min); > @@ -1353,7 +1363,9 @@ static void cpufreq_policy_free(struct cpufreq_policy *policy) > &policy->nb_min); > > /* Cancel any pending policy->update work before freeing the policy. */ > - cancel_work_sync(&policy->update); > + kthread_cancel_work_sync(&policy->update); > + if (policy->worker) > + kthread_destroy_worker(policy->worker); > > if (policy->max_freq_req) { > /* > @@ -1802,7 +1814,7 @@ static unsigned int cpufreq_verify_current_freq(struct cpufreq_policy *policy, b > > cpufreq_out_of_sync(policy, new_freq); > if (update) > - schedule_work(&policy->update); > + kthread_queue_work(policy->worker, &policy->update); > } > > return new_freq; > diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h > index 20f7e98ee8af..73029daddfc5 100644 > --- a/include/linux/cpufreq.h > +++ b/include/linux/cpufreq.h > @@ -20,6 +20,7 @@ > #include <linux/spinlock.h> > #include <linux/sysfs.h> > #include <linux/minmax.h> > +#include <linux/kthread.h> > > /********************************************************************* > * CPUFREQ INTERFACE * > @@ -77,8 +78,9 @@ struct cpufreq_policy { > void *governor_data; > char last_governor[CPUFREQ_NAME_LEN]; /* last governor used */ > > - struct work_struct update; /* if update_policy() needs to be > + struct kthread_work update; /* if update_policy() needs to be > * called, but you're in IRQ context */ > + struct kthread_worker *worker; > > struct freq_constraints constraints; > struct freq_qos_request *min_freq_req;
Hi Tim, On 2024/7/19 6:03, Tim Chen wrote: > On Wed, 2024-07-17 at 14:33 +0800, Gaowei Pu wrote: >> Currently we encountered a problem that the cpufreq boost latency >> is about 10 milliseconds or worse when we boost through cpufreq QOS request >> under high workload scenarios, while the boost latency mainly consumed by >> schedule latency of policy->update work. > > What is the tail latency now after your change? > >> >> We should ensure the low schedule latency of cpu frequency limits work >> to meet performance and power demands. so queue the policy->update work >> to rt thread to reduce its schedule latency. > > If my understanding is correct, kthread has a default nice > value of 0 and is not a rt thread. > > I think the gain you see is > your patch created a dedicated kthread work queue on CPU 0. > The work from policy change no longer have to compete time with other > requests coming from schedule_work(). It's not just other requests coming from schedule_work(), also some normal cfs tasks running on the same cpu. In order to not competing time with the above threads, i change the thread policy to rt and prio set to 98 to reduce the schedule latency. > > If the policy change really needs to get ahead > of other tasks, I think you need a dedicated > workqueue with alloc_workqueue() using WQ_HIGHPRI flag.I think the cpufreq boost or limit action should be trigger in time to meet performance and power demands. An dedicated workqueue with highpri will be better but maybe not good enough because cfs pick or preempt policy is not purely based on thread nice value. So i think the final solution is rt thread and the policy change work deserves it :) thanks. > > Tim > >> >> Signed-off-by: Gaowei Pu <pugaowei@oppo.com> >> --- >> drivers/cpufreq/cpufreq.c | 24 ++++++++++++++++++------ >> include/linux/cpufreq.h | 4 +++- >> 2 files changed, 21 insertions(+), 7 deletions(-) >> >> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c >> index a45aac17c20f..e6e42a3ba9ab 100644 >> --- a/drivers/cpufreq/cpufreq.c >> +++ b/drivers/cpufreq/cpufreq.c >> @@ -1193,7 +1193,7 @@ void refresh_frequency_limits(struct cpufreq_policy *policy) >> } >> EXPORT_SYMBOL(refresh_frequency_limits); >> >> -static void handle_update(struct work_struct *work) >> +static void handle_update(struct kthread_work *work) >> { >> struct cpufreq_policy *policy = >> container_of(work, struct cpufreq_policy, update); >> @@ -1209,7 +1209,7 @@ static int cpufreq_notifier_min(struct notifier_block *nb, unsigned long freq, >> { >> struct cpufreq_policy *policy = container_of(nb, struct cpufreq_policy, nb_min); >> >> - schedule_work(&policy->update); >> + kthread_queue_work(policy->worker, &policy->update); >> return 0; >> } >> >> @@ -1218,7 +1218,7 @@ static int cpufreq_notifier_max(struct notifier_block *nb, unsigned long freq, >> { >> struct cpufreq_policy *policy = container_of(nb, struct cpufreq_policy, nb_max); >> >> - schedule_work(&policy->update); >> + kthread_queue_work(policy->worker, &policy->update); >> return 0; >> } >> >> @@ -1301,15 +1301,25 @@ static struct cpufreq_policy *cpufreq_policy_alloc(unsigned int cpu) >> goto err_min_qos_notifier; >> } >> >> + policy->worker = kthread_create_worker_on_cpu(cpu, 0, "policy_worker%d", cpu); >> + if (IS_ERR(policy->worker)) { >> + dev_err(dev, "Failed to create policy_worker%d\n", cpu); >> + goto err_max_qos_notifier; >> + } >> + >> + sched_set_fifo_low(policy->worker->task); >> INIT_LIST_HEAD(&policy->policy_list); >> init_rwsem(&policy->rwsem); >> spin_lock_init(&policy->transition_lock); >> init_waitqueue_head(&policy->transition_wait); >> - INIT_WORK(&policy->update, handle_update); >> + kthread_init_work(&policy->update, handle_update); >> >> policy->cpu = cpu; >> return policy; >> >> +err_max_qos_notifier: >> + freq_qos_remove_notifier(&policy->constraints, FREQ_QOS_MAX, >> + &policy->nb_max); >> err_min_qos_notifier: >> freq_qos_remove_notifier(&policy->constraints, FREQ_QOS_MIN, >> &policy->nb_min); >> @@ -1353,7 +1363,9 @@ static void cpufreq_policy_free(struct cpufreq_policy *policy) >> &policy->nb_min); >> >> /* Cancel any pending policy->update work before freeing the policy. */ >> - cancel_work_sync(&policy->update); >> + kthread_cancel_work_sync(&policy->update); >> + if (policy->worker) >> + kthread_destroy_worker(policy->worker); >> >> if (policy->max_freq_req) { >> /* >> @@ -1802,7 +1814,7 @@ static unsigned int cpufreq_verify_current_freq(struct cpufreq_policy *policy, b >> >> cpufreq_out_of_sync(policy, new_freq); >> if (update) >> - schedule_work(&policy->update); >> + kthread_queue_work(policy->worker, &policy->update); >> } >> >> return new_freq; >> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h >> index 20f7e98ee8af..73029daddfc5 100644 >> --- a/include/linux/cpufreq.h >> +++ b/include/linux/cpufreq.h >> @@ -20,6 +20,7 @@ >> #include <linux/spinlock.h> >> #include <linux/sysfs.h> >> #include <linux/minmax.h> >> +#include <linux/kthread.h> >> >> /********************************************************************* >> * CPUFREQ INTERFACE * >> @@ -77,8 +78,9 @@ struct cpufreq_policy { >> void *governor_data; >> char last_governor[CPUFREQ_NAME_LEN]; /* last governor used */ >> >> - struct work_struct update; /* if update_policy() needs to be >> + struct kthread_work update; /* if update_policy() needs to be >> * called, but you're in IRQ context */ >> + struct kthread_worker *worker; >> >> struct freq_constraints constraints; >> struct freq_qos_request *min_freq_req; >
On 2024/7/22 10:30, Gaowei Pu wrote: > Hi Tim, > > On 2024/7/19 6:03, Tim Chen wrote: >> On Wed, 2024-07-17 at 14:33 +0800, Gaowei Pu wrote: >>> Currently we encountered a problem that the cpufreq boost latency >>> is about 10 milliseconds or worse when we boost through cpufreq QOS request >>> under high workload scenarios, while the boost latency mainly consumed by >>> schedule latency of policy->update work. >> >> What is the tail latency now after your change? sorry missed this. the tail latency now is about within 50 microseconds after my change. >> >>> >>> We should ensure the low schedule latency of cpu frequency limits work >>> to meet performance and power demands. so queue the policy->update work >>> to rt thread to reduce its schedule latency. >> >> If my understanding is correct, kthread has a default nice >> value of 0 and is not a rt thread. >> >> I think the gain you see is >> your patch created a dedicated kthread work queue on CPU 0. >> The work from policy change no longer have to compete time with other >> requests coming from schedule_work(). > It's not just other requests coming from schedule_work(), also some normal > cfs tasks running on the same cpu. > > In order to not competing time with the above threads, i change the thread > policy to rt and prio set to 98 to reduce the schedule latency. >> >> If the policy change really needs to get ahead >> of other tasks, I think you need a dedicated >> workqueue with alloc_workqueue() using WQ_HIGHPRI flag. > I think the cpufreq boost or limit action should be trigger in time to meet > performance and power demands. An dedicated workqueue with highpri will be > better but maybe not good enough because cfs pick or preempt policy is not > purely based on thread nice value. So i think the final solution is rt thread > and the policy change work deserves it :) > thanks. >> >> Tim >> >>> >>> Signed-off-by: Gaowei Pu <pugaowei@oppo.com> >>> --- >>> drivers/cpufreq/cpufreq.c | 24 ++++++++++++++++++------ >>> include/linux/cpufreq.h | 4 +++- >>> 2 files changed, 21 insertions(+), 7 deletions(-) >>> >>> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c >>> index a45aac17c20f..e6e42a3ba9ab 100644 >>> --- a/drivers/cpufreq/cpufreq.c >>> +++ b/drivers/cpufreq/cpufreq.c >>> @@ -1193,7 +1193,7 @@ void refresh_frequency_limits(struct cpufreq_policy *policy) >>> } >>> EXPORT_SYMBOL(refresh_frequency_limits); >>> >>> -static void handle_update(struct work_struct *work) >>> +static void handle_update(struct kthread_work *work) >>> { >>> struct cpufreq_policy *policy = >>> container_of(work, struct cpufreq_policy, update); >>> @@ -1209,7 +1209,7 @@ static int cpufreq_notifier_min(struct notifier_block *nb, unsigned long freq, >>> { >>> struct cpufreq_policy *policy = container_of(nb, struct cpufreq_policy, nb_min); >>> >>> - schedule_work(&policy->update); >>> + kthread_queue_work(policy->worker, &policy->update); >>> return 0; >>> } >>> >>> @@ -1218,7 +1218,7 @@ static int cpufreq_notifier_max(struct notifier_block *nb, unsigned long freq, >>> { >>> struct cpufreq_policy *policy = container_of(nb, struct cpufreq_policy, nb_max); >>> >>> - schedule_work(&policy->update); >>> + kthread_queue_work(policy->worker, &policy->update); >>> return 0; >>> } >>> >>> @@ -1301,15 +1301,25 @@ static struct cpufreq_policy *cpufreq_policy_alloc(unsigned int cpu) >>> goto err_min_qos_notifier; >>> } >>> >>> + policy->worker = kthread_create_worker_on_cpu(cpu, 0, "policy_worker%d", cpu); >>> + if (IS_ERR(policy->worker)) { >>> + dev_err(dev, "Failed to create policy_worker%d\n", cpu); >>> + goto err_max_qos_notifier; >>> + } >>> + >>> + sched_set_fifo_low(policy->worker->task); >>> INIT_LIST_HEAD(&policy->policy_list); >>> init_rwsem(&policy->rwsem); >>> spin_lock_init(&policy->transition_lock); >>> init_waitqueue_head(&policy->transition_wait); >>> - INIT_WORK(&policy->update, handle_update); >>> + kthread_init_work(&policy->update, handle_update); >>> >>> policy->cpu = cpu; >>> return policy; >>> >>> +err_max_qos_notifier: >>> + freq_qos_remove_notifier(&policy->constraints, FREQ_QOS_MAX, >>> + &policy->nb_max); >>> err_min_qos_notifier: >>> freq_qos_remove_notifier(&policy->constraints, FREQ_QOS_MIN, >>> &policy->nb_min); >>> @@ -1353,7 +1363,9 @@ static void cpufreq_policy_free(struct cpufreq_policy *policy) >>> &policy->nb_min); >>> >>> /* Cancel any pending policy->update work before freeing the policy. */ >>> - cancel_work_sync(&policy->update); >>> + kthread_cancel_work_sync(&policy->update); >>> + if (policy->worker) >>> + kthread_destroy_worker(policy->worker); >>> >>> if (policy->max_freq_req) { >>> /* >>> @@ -1802,7 +1814,7 @@ static unsigned int cpufreq_verify_current_freq(struct cpufreq_policy *policy, b >>> >>> cpufreq_out_of_sync(policy, new_freq); >>> if (update) >>> - schedule_work(&policy->update); >>> + kthread_queue_work(policy->worker, &policy->update); >>> } >>> >>> return new_freq; >>> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h >>> index 20f7e98ee8af..73029daddfc5 100644 >>> --- a/include/linux/cpufreq.h >>> +++ b/include/linux/cpufreq.h >>> @@ -20,6 +20,7 @@ >>> #include <linux/spinlock.h> >>> #include <linux/sysfs.h> >>> #include <linux/minmax.h> >>> +#include <linux/kthread.h> >>> >>> /********************************************************************* >>> * CPUFREQ INTERFACE * >>> @@ -77,8 +78,9 @@ struct cpufreq_policy { >>> void *governor_data; >>> char last_governor[CPUFREQ_NAME_LEN]; /* last governor used */ >>> >>> - struct work_struct update; /* if update_policy() needs to be >>> + struct kthread_work update; /* if update_policy() needs to be >>> * called, but you're in IRQ context */ >>> + struct kthread_worker *worker; >>> >>> struct freq_constraints constraints; >>> struct freq_qos_request *min_freq_req; >> >
On Mon, Jul 22, 2024 at 4:30 AM Gaowei Pu <pugaowei@oppo.com> wrote: > > Hi Tim, > > On 2024/7/19 6:03, Tim Chen wrote: > > On Wed, 2024-07-17 at 14:33 +0800, Gaowei Pu wrote: > >> Currently we encountered a problem that the cpufreq boost latency > >> is about 10 milliseconds or worse when we boost through cpufreq QOS request > >> under high workload scenarios, while the boost latency mainly consumed by > >> schedule latency of policy->update work. > > > > What is the tail latency now after your change? > > > >> > >> We should ensure the low schedule latency of cpu frequency limits work > >> to meet performance and power demands. so queue the policy->update work > >> to rt thread to reduce its schedule latency. > > > > If my understanding is correct, kthread has a default nice > > value of 0 and is not a rt thread. > > > > I think the gain you see is > > your patch created a dedicated kthread work queue on CPU 0. > > The work from policy change no longer have to compete time with other > > requests coming from schedule_work(). > > It's not just other requests coming from schedule_work(), also some normal > cfs tasks running on the same cpu. Do you have any data to support this statement? > In order to not competing time with the above threads, i change the thread > policy to rt and prio set to 98 to reduce the schedule latency. By how much? > > > > If the policy change really needs to get ahead > > of other tasks, I think you need a dedicated > > workqueue with alloc_workqueue() using WQ_HIGHPRI flag. > > I think the cpufreq boost or limit action should be trigger in time to meet > performance and power demands. An dedicated workqueue with highpri will be > better but maybe not good enough because cfs pick or preempt policy is not > purely based on thread nice value. So i think the final solution is rt thread > and the policy change work deserves it :) The "I think" and "maybe" in the above paragraph are not particularly convincing. Switching it over to use a dedicated workqueue would be a no-brainer as using dedicated workqueues is recommended anyway and if it measurably improves performance, that's for the better. However, making it use a worker thread the way this patch does requires quite a clear demonstration that the above is not sufficient. Thanks!
Hi Rafael J, On 2024/8/27 1:48, Rafael J. Wysocki wrote: > On Mon, Jul 22, 2024 at 4:30 AM Gaowei Pu <pugaowei@oppo.com> wrote: >> >> Hi Tim, >> >> On 2024/7/19 6:03, Tim Chen wrote: >>> On Wed, 2024-07-17 at 14:33 +0800, Gaowei Pu wrote: >>>> Currently we encountered a problem that the cpufreq boost latency >>>> is about 10 milliseconds or worse when we boost through cpufreq QOS request >>>> under high workload scenarios, while the boost latency mainly consumed by >>>> schedule latency of policy->update work. >>> >>> What is the tail latency now after your change? >>> >>>> >>>> We should ensure the low schedule latency of cpu frequency limits work >>>> to meet performance and power demands. so queue the policy->update work >>>> to rt thread to reduce its schedule latency. >>> >>> If my understanding is correct, kthread has a default nice >>> value of 0 and is not a rt thread. >>> >>> I think the gain you see is >>> your patch created a dedicated kthread work queue on CPU 0. >>> The work from policy change no longer have to compete time with other >>> requests coming from schedule_work(). >> >> It's not just other requests coming from schedule_work(), also some normal >> cfs tasks running on the same cpu. > > Do you have any data to support this statement? Yes, i have some systraces in high workload android scenarios. will send to you if needed. > >> In order to not competing time with the above threads, i change the thread >> policy to rt and prio set to 98 to reduce the schedule latency. > > By how much? the tail latency now is about within 50 microseconds after my change. > >>> >>> If the policy change really needs to get ahead >>> of other tasks, I think you need a dedicated >>> workqueue with alloc_workqueue() using WQ_HIGHPRI flag. >> >> I think the cpufreq boost or limit action should be trigger in time to meet >> performance and power demands. An dedicated workqueue with highpri will be >> better but maybe not good enough because cfs pick or preempt policy is not >> purely based on thread nice value. So i think the final solution is rt thread >> and the policy change work deserves it :) > > The "I think" and "maybe" in the above paragraph are not particularly > convincing. > > Switching it over to use a dedicated workqueue would be a no-brainer > as using dedicated workqueues is recommended anyway and if it > measurably improves performance, that's for the better. Ok, thanks for your and Tim's advice. I used the dedicated workqueue with highpri(tested and the sched latency is within 1ms) to replace the rt thread and will send v2 later. > > However, making it use a worker thread the way this patch does > requires quite a clear demonstration that the above is not sufficient. > > Thanks!
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index a45aac17c20f..e6e42a3ba9ab 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1193,7 +1193,7 @@ void refresh_frequency_limits(struct cpufreq_policy *policy) } EXPORT_SYMBOL(refresh_frequency_limits); -static void handle_update(struct work_struct *work) +static void handle_update(struct kthread_work *work) { struct cpufreq_policy *policy = container_of(work, struct cpufreq_policy, update); @@ -1209,7 +1209,7 @@ static int cpufreq_notifier_min(struct notifier_block *nb, unsigned long freq, { struct cpufreq_policy *policy = container_of(nb, struct cpufreq_policy, nb_min); - schedule_work(&policy->update); + kthread_queue_work(policy->worker, &policy->update); return 0; } @@ -1218,7 +1218,7 @@ static int cpufreq_notifier_max(struct notifier_block *nb, unsigned long freq, { struct cpufreq_policy *policy = container_of(nb, struct cpufreq_policy, nb_max); - schedule_work(&policy->update); + kthread_queue_work(policy->worker, &policy->update); return 0; } @@ -1301,15 +1301,25 @@ static struct cpufreq_policy *cpufreq_policy_alloc(unsigned int cpu) goto err_min_qos_notifier; } + policy->worker = kthread_create_worker_on_cpu(cpu, 0, "policy_worker%d", cpu); + if (IS_ERR(policy->worker)) { + dev_err(dev, "Failed to create policy_worker%d\n", cpu); + goto err_max_qos_notifier; + } + + sched_set_fifo_low(policy->worker->task); INIT_LIST_HEAD(&policy->policy_list); init_rwsem(&policy->rwsem); spin_lock_init(&policy->transition_lock); init_waitqueue_head(&policy->transition_wait); - INIT_WORK(&policy->update, handle_update); + kthread_init_work(&policy->update, handle_update); policy->cpu = cpu; return policy; +err_max_qos_notifier: + freq_qos_remove_notifier(&policy->constraints, FREQ_QOS_MAX, + &policy->nb_max); err_min_qos_notifier: freq_qos_remove_notifier(&policy->constraints, FREQ_QOS_MIN, &policy->nb_min); @@ -1353,7 +1363,9 @@ static void cpufreq_policy_free(struct cpufreq_policy *policy) &policy->nb_min); /* Cancel any pending policy->update work before freeing the policy. */ - cancel_work_sync(&policy->update); + kthread_cancel_work_sync(&policy->update); + if (policy->worker) + kthread_destroy_worker(policy->worker); if (policy->max_freq_req) { /* @@ -1802,7 +1814,7 @@ static unsigned int cpufreq_verify_current_freq(struct cpufreq_policy *policy, b cpufreq_out_of_sync(policy, new_freq); if (update) - schedule_work(&policy->update); + kthread_queue_work(policy->worker, &policy->update); } return new_freq; diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index 20f7e98ee8af..73029daddfc5 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -20,6 +20,7 @@ #include <linux/spinlock.h> #include <linux/sysfs.h> #include <linux/minmax.h> +#include <linux/kthread.h> /********************************************************************* * CPUFREQ INTERFACE * @@ -77,8 +78,9 @@ struct cpufreq_policy { void *governor_data; char last_governor[CPUFREQ_NAME_LEN]; /* last governor used */ - struct work_struct update; /* if update_policy() needs to be + struct kthread_work update; /* if update_policy() needs to be * called, but you're in IRQ context */ + struct kthread_worker *worker; struct freq_constraints constraints; struct freq_qos_request *min_freq_req;
Currently we encountered a problem that the cpufreq boost latency is about 10 milliseconds or worse when we boost through cpufreq QOS request under high workload scenarios, while the boost latency mainly consumed by schedule latency of policy->update work. We should ensure the low schedule latency of cpu frequency limits work to meet performance and power demands. so queue the policy->update work to rt thread to reduce its schedule latency. Signed-off-by: Gaowei Pu <pugaowei@oppo.com> --- drivers/cpufreq/cpufreq.c | 24 ++++++++++++++++++------ include/linux/cpufreq.h | 4 +++- 2 files changed, 21 insertions(+), 7 deletions(-)