Messages in this thread | | | From | "Song Bao Hua (Barry Song)" <> | Subject | RE: [RFC PATCH v2 2/2] scheduler: add scheduler level for clusters | Date | Thu, 3 Dec 2020 09:57:09 +0000 |
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> -----Original Message----- > From: Peter Zijlstra [mailto:peterz@infradead.org] > Sent: Thursday, December 3, 2020 10:29 PM > To: Valentin Schneider <valentin.schneider@arm.com> > Cc: Song Bao Hua (Barry Song) <song.bao.hua@hisilicon.com>; > catalin.marinas@arm.com; will@kernel.org; rjw@rjwysocki.net; lenb@kernel.org; > gregkh@linuxfoundation.org; Jonathan Cameron <jonathan.cameron@huawei.com>; > mingo@redhat.com; juri.lelli@redhat.com; vincent.guittot@linaro.org; > dietmar.eggemann@arm.com; rostedt@goodmis.org; bsegall@google.com; > mgorman@suse.de; mark.rutland@arm.com; linux-arm-kernel@lists.infradead.org; > linux-kernel@vger.kernel.org; linux-acpi@vger.kernel.org; Linuxarm > <linuxarm@huawei.com>; xuwei (O) <xuwei5@huawei.com>; Zengtao (B) > <prime.zeng@hisilicon.com> > 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
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