On 03/18/24 18:08, Rafael J. Wysocki wrote: > On Mon, Mar 18, 2024 at 5:40 PM Christian Loehle > <christian.loehle@xxxxxxx> wrote: > > > > On 18/03/2024 14:07, Rafael J. Wysocki wrote: > > > On Mon, Mar 4, 2024 at 9:17 PM Christian Loehle > > > <christian.loehle@xxxxxxx> wrote: > > >> > > >> The previous commit provides a new cpu_util_cfs_boost_io interface for > > >> schedutil which uses the io boosted utilization of the per-task > > >> tracking strategy. Schedutil iowait boosting is therefore no longer > > >> necessary so remove it. > > > > > > I'm wondering about the cases when schedutil is used without EAS. > > > > > > Are they still going to be handled as before after this change? > > > > Well they should still get boosted (under the new conditions) and according > > to my tests that does work. > > OK > > > Anything in particular you're worried about? > > It is not particularly clear to me how exactly the boost is taken into > account without EAS. > > > So in terms of throughput I see similar results with EAS and CAS+sugov. > > I'm happy including numbers in the cover letter for future versions, too. > > So far my intuition was that nobody would care enough to include them > > (as long as it generally still works). > > Well, IMV clear understanding of the changes is more important. I think the major thing we need to be careful about is the behavior when the task is sleeping. I think the boosting will be removed when the task is dequeued and I can bet there will be systems out there where the BLOCK softirq being boosted when the task is sleeping will matter. FWIW I do have an implementation for per-task iowait boost where I went a step further and converted intel_pstate too and like Christian didn't notice a regression. But I am not sure (rather don't think) I triggered this use case. I can't tell when the systems truly have per-cpu cpufreq control or just appear so and they are actually shared but not visible at linux level.
