On 21/05/18 10:29, Rafael J. Wysocki wrote: > On Mon, May 21, 2018 at 7:14 AM, Viresh Kumar <[email protected]> wrote: > > On 18-05-18, 11:55, Joel Fernandes (Google.) wrote: > >> From: "Joel Fernandes (Google)" <[email protected]> > >> > >> Currently there is a chance of a schedutil cpufreq update request to be > >> dropped if there is a pending update request. This pending request can > >> be delayed if there is a scheduling delay of the irq_work and the wake > >> up of the schedutil governor kthread. > >> > >> A very bad scenario is when a schedutil request was already just made, > >> such as to reduce the CPU frequency, then a newer request to increase > >> CPU frequency (even sched deadline urgent frequency increase requests) > >> can be dropped, even though the rate limits suggest that its Ok to > >> process a request. This is because of the way the work_in_progress flag > >> is used. > >> > >> This patch improves the situation by allowing new requests to happen > >> even though the old one is still being processed. Note that in this > >> approach, if an irq_work was already issued, we just update next_freq > >> and don't bother to queue another request so there's no extra work being > >> done to make this happen. > > > > Now that this isn't an RFC anymore, you shouldn't have added below > > paragraph here. It could go to the comments section though. > > > >> I had brought up this issue at the OSPM conference and Claudio had a > >> discussion RFC with an alternate approach [1]. I prefer the approach as > >> done in the patch below since it doesn't need any new flags and doesn't > >> cause any other extra overhead. > >> > >> [1] https://patchwork.kernel.org/patch/10384261/ > >> > >> LGTMed-by: Viresh Kumar <[email protected]> > >> LGTMed-by: Juri Lelli <[email protected]> > > > > Looks like a Tag you just invented ? :) > > Yeah. > > The LGTM from Juri can be converned into an ACK silently IMO. That
Sure! :) Thanks, - Juri
