Messages in this thread | | | Date | Tue, 8 May 2018 23:55:16 -0700 | From | Joel Fernandes <> | Subject | Re: [RFC PATCH] sched/cpufreq/schedutil: handling urgent frequency requests |
| |
On Wed, May 09, 2018 at 08:45:30AM +0200, Juri Lelli wrote: > On 08/05/18 21:54, Joel Fernandes wrote: > > [...] > > > Just for discussion sake, is there any need for work_in_progress? If we can > > queue multiple work say kthread_queue_work can handle it, then just queuing > > works whenever they are available should be Ok and the kthread loop can > > handle them. __cpufreq_driver_target is also protected by the work lock if > > there is any concern that can have races... only thing is rate-limiting of > > the requests, but we are doing a rate limiting, just not for the "DL > > increased utilization" type requests (which I don't think we are doing at the > > moment for urgent DL requests anyway). > > > > Following is an untested diff to show the idea. What do you think? > > > > thanks, > > > > - Joel > > > > ----8<--- > > diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c > > index d2c6083304b4..862634ff4bf3 100644 > > --- a/kernel/sched/cpufreq_schedutil.c > > +++ b/kernel/sched/cpufreq_schedutil.c > > @@ -38,7 +38,6 @@ struct sugov_policy { > > struct mutex work_lock; > > struct kthread_worker worker; > > struct task_struct *thread; > > - bool work_in_progress; > > > > bool need_freq_update; > > }; > > @@ -92,16 +91,8 @@ static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time) > > !cpufreq_can_do_remote_dvfs(sg_policy->policy)) > > return false; > > > > - if (sg_policy->work_in_progress) > > - return false; > > - > > if (unlikely(sg_policy->need_freq_update)) { > > sg_policy->need_freq_update = false; > > - /* > > - * This happens when limits change, so forget the previous > > - * next_freq value and force an update. > > - */ > > - sg_policy->next_freq = UINT_MAX; > > return true; > > } > > > > @@ -129,7 +120,6 @@ static void sugov_update_commit(struct sugov_policy *sg_policy, u64 time, > > policy->cur = next_freq; > > trace_cpu_frequency(next_freq, smp_processor_id()); > > } else { > > - sg_policy->work_in_progress = true; > > irq_work_queue(&sg_policy->irq_work); > > Isn't this potentially introducing unneeded irq pressure (and doing the > whole wakeup the kthread thing), while the already active kthread could > simply handle multiple back-to-back requests before going to sleep?
Yes, I was also thinking the same. I think we can come up with a better mechanism that still doesn't use work_in_progress. I am cooking up a patch but may take a bit longer since I'm traveling. I'll share it once I have something :)
thanks,
- Joel
| |