On Thu, Oct 22, 2020 at 09:32:55PM +0100 Mel Gorman wrote: > On Thu, Oct 22, 2020 at 07:59:43PM +0200, Rafael J. Wysocki wrote: > > > > Agreed. I'd like the option to switch back if we make the default change. > > > > It's on the table and I'd like to be able to go that way. > > > > > > > > > > Yep. It sounds chicken, but it's a useful safety net and a reasonable > > > way to deprecate a feature. It's also useful for bug creation -- User X > > > running whatever found that schedutil is worse than the old governor and > > > had to temporarily switch back. Repeat until complaining stops and then > > > tear out the old stuff. > > > > > > When/if there is a patch setting schedutil as the default, cc suitable > > > distro people (Giovanni and myself for openSUSE). > > > > So for the record, Giovanni was on the CC list of the "cpufreq: > > intel_pstate: Use passive mode by default without HWP" patch that this > > discussion resulted from (and which kind of belongs to the above > > category). > > > > Oh I know, I did not mean to suggest that you did not. He made people > aware that this was going to be coming down the line and has been looking > into the "what if schedutil was the default" question. AFAIK, it's still > a work-in-progress and I don't know all the specifics but he knows more > than I do on the topic. I only know enough that if we flipped the switch > tomorrow that we could be plagued with google searches suggesting it be > turned off again just like there is still broken advice out there about > disabling intel_pstate for usually the wrong reasons. > > The passive patch was a clear flag that the intent is that schedutil will > be the default at some unknown point in the future. That point is now a > bit closer and this thread could have encouraged a premature change of > the default resulting in unfair finger pointing at one company's test > team. If at least two distos check it out and it still goes wrong, at > least there will be shared blame :/ > > > > Other distros assuming they're watching can nominate their own victim. > > > > But no other victims had been nominated at that time. > > We have one, possibly two if Phil agrees. That's better than zero or > unfairly placing the full responsibility on the Intel guys that have been > testing it out. > Yes. I agree and we (RHEL) are planning to test this soon. I'll try to get to it. You can certainly CC me, please, athough I also try to watch for this sort of thing on list. Cheers, Phil > -- > Mel Gorman > SUSE Labs > --
