> -----Original Message----- > From: Peter Zijlstra [mailto:peterz@xxxxxxxxxxxxx] > Sent: Thursday, December 3, 2020 10:29 PM > To: Valentin Schneider <valentin.schneider@xxxxxxx> > Cc: Song Bao Hua (Barry Song) <song.bao.hua@xxxxxxxxxxxxx>; > catalin.marinas@xxxxxxx; will@xxxxxxxxxx; rjw@xxxxxxxxxxxxx; lenb@xxxxxxxxxx; > gregkh@xxxxxxxxxxxxxxxxxxx; Jonathan Cameron <jonathan.cameron@xxxxxxxxxx>; > mingo@xxxxxxxxxx; juri.lelli@xxxxxxxxxx; vincent.guittot@xxxxxxxxxx; > dietmar.eggemann@xxxxxxx; rostedt@xxxxxxxxxxx; bsegall@xxxxxxxxxx; > mgorman@xxxxxxx; mark.rutland@xxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; > linux-kernel@xxxxxxxxxxxxxxx; linux-acpi@xxxxxxxxxxxxxxx; Linuxarm > <linuxarm@xxxxxxxxxx>; xuwei (O) <xuwei5@xxxxxxxxxx>; Zengtao (B) > <prime.zeng@xxxxxxxxxxxxx> > Subject: Re: [RFC PATCH v2 2/2] scheduler: add scheduler level for clusters > > On Tue, Dec 01, 2020 at 04:04:04PM +0000, Valentin Schneider wrote: > > > > Gating this behind this new config only leveraged by arm64 doesn't make it > > very generic. Note that powerpc also has this newish "CACHE" level which > > seems to overlap in function with your "CLUSTER" one (both are arch > > specific, though). > > > > I think what you are after here is an SD_SHARE_PKG_RESOURCES domain walk, > > i.e. scan CPUs by increasing cache "distance". We already have it in some > > form, as we scan SMT & LLC domains; AFAICT LLC always maps to MC, except > > for said powerpc's CACHE thingie. > > There's some intel chips with a smaller L2, but I don't think we ever > bothered. > > There's also the extended topology stuff from Intel: SMT, Core, Module, > Tile, Die, of which we've only partially used Die I think. > > Whatever we do, it might make sense to not all use different names. Yep. Valentin was actually recommending the same SD_SHARE_PKG_RESOURCES sd flags by ignoring the actual names of the hardware. But the question is where we should start, in case we have 3 domains under llc, maybe it is not good to scan from the first level domain as it is gathering too much. > > Also, I think Mel said he was cooking something for > select_idle_balance(). > > Also, I've previously posted patches that fold all the iterations into > one, so it might make sense to revisit some of that if Mel also already > didn.t Would you point out the link of your previous patches? Thanks Barry
