On Wed, Dec 20, 2017 at 12:55:46PM +0000, Patrick Bellasi wrote: > On 20-Dec 09:31, Peter Zijlstra wrote:
> > Didn't juri have patches to make DL do something sane? But yes, I think > > those flags are part of the problem. > > He recently reposted them here: > > https://lkml.kernel.org/r/20171204102325.5110-1-juri.le...@redhat.com Yeah, just found them and actually munged them into my queue; did all the modifications you suggested too. Lets see if it comes apart. > > > - From the utilization handler, we check runqueues of all three sched > > > classes to see if they have some work pending (this can be done > > > smartly by checking only RT first and skipping other checks if RT > > > has some work). > > > > No that's wrong. DL should provide a minimum required based on existing > > reservations, we can add the expected CFS average on top and request > > that. > > > > And for RT all we need to know is if current is of that class, otherwise > > we don't care. > > So, this: > > https://marc.info/?i=20171130114723.29210-3-patrick.bellasi%40arm.com Right, I was actually looking for those patches, but I'm searching backwards and hit upon Juri's patches first. > was actually going in this direction, although still working on top of > flags to not change the existing interface too much. > > IMO, the advantage of flags is that they are a sort-of "pro-active" > approach, where the scheduler notify sensible events to schedutil. > But keep adding flags seems to overkilling to me too. > > If we remove flags then we have to query the scheduler classes "on > demand"... but, as Peter suggests, once we have DL bits Juri posted, > the only issue if to know if an RT task is running. > This the patch above can be just good enough, with no flags at all and > with just a check for current being RT (or DL for the time being). Well, we still need flags for crap like IO-WAIT IIRC. That's sugov internal state and not something the scheduler actually already knows. But let me continue searching for patches.. Ooh, I found patches from Brendan... should be very close to yours though, going by that msgid you posted on Nov 30th and I'm now on Dec 1st, soooon... :-)
