linux-kernel - RE: [RFC PATCH v5 4/4] scheduler: Add cluster scheduler level for x86

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Date:   Wed, 31 Mar 2021 10:07:28 +0000
From:   "Song Bao Hua (Barry Song)" <song.bao.hua@...ilicon.com>
To:     Tim Chen <tim.c.chen@...ux.intel.com>,
        "catalin.marinas@....com" <catalin.marinas@....com>,
        "will@...nel.org" <will@...nel.org>,
        "rjw@...ysocki.net" <rjw@...ysocki.net>,
        "vincent.guittot@...aro.org" <vincent.guittot@...aro.org>,
        "bp@...en8.de" <bp@...en8.de>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "lenb@...nel.org" <lenb@...nel.org>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "dietmar.eggemann@....com" <dietmar.eggemann@....com>,
        "rostedt@...dmis.org" <rostedt@...dmis.org>,
        "bsegall@...gle.com" <bsegall@...gle.com>,
        "mgorman@...e.de" <mgorman@...e.de>
CC:     "msys.mizuma@...il.com" <msys.mizuma@...il.com>,
        "valentin.schneider@....com" <valentin.schneider@....com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        Jonathan Cameron <jonathan.cameron@...wei.com>,
        "juri.lelli@...hat.com" <juri.lelli@...hat.com>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "sudeep.holla@....com" <sudeep.holla@....com>,
        "aubrey.li@...ux.intel.com" <aubrey.li@...ux.intel.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
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        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>, "xuwei (O)" <xuwei5@...wei.com>,
        "Zengtao (B)" <prime.zeng@...ilicon.com>,
        "guodong.xu@...aro.org" <guodong.xu@...aro.org>,
        yangyicong <yangyicong@...wei.com>,
        "Liguozhu (Kenneth)" <liguozhu@...ilicon.com>,
        "linuxarm@...neuler.org" <linuxarm@...neuler.org>,
        "hpa@...or.com" <hpa@...or.com>
Subject: RE: [RFC PATCH v5 4/4] scheduler: Add cluster scheduler level for x86



> -----Original Message-----
> From: Song Bao Hua (Barry Song)
> Sent: Wednesday, March 24, 2021 12:15 PM
> To: 'Tim Chen' <tim.c.chen@...ux.intel.com>; catalin.marinas@....com;
> will@...nel.org; rjw@...ysocki.net; vincent.guittot@...aro.org; bp@...en8.de;
> tglx@...utronix.de; mingo@...hat.com; lenb@...nel.org; peterz@...radead.org;
> dietmar.eggemann@....com; rostedt@...dmis.org; bsegall@...gle.com;
> mgorman@...e.de
> Cc: msys.mizuma@...il.com; valentin.schneider@....com;
> gregkh@...uxfoundation.org; Jonathan Cameron <jonathan.cameron@...wei.com>;
> juri.lelli@...hat.com; mark.rutland@....com; sudeep.holla@....com;
> aubrey.li@...ux.intel.com; linux-arm-kernel@...ts.infradead.org;
> linux-kernel@...r.kernel.org; linux-acpi@...r.kernel.org; x86@...nel.org;
> xuwei (O) <xuwei5@...wei.com>; Zengtao (B) <prime.zeng@...ilicon.com>;
> guodong.xu@...aro.org; yangyicong <yangyicong@...wei.com>; Liguozhu (Kenneth)
> <liguozhu@...ilicon.com>; linuxarm@...neuler.org; hpa@...or.com
> Subject: RE: [RFC PATCH v5 4/4] scheduler: Add cluster scheduler level for x86
> 
> 
> 
> > -----Original Message-----
> > From: Tim Chen [mailto:tim.c.chen@...ux.intel.com]
> > Sent: Wednesday, March 24, 2021 11:51 AM
> > To: Song Bao Hua (Barry Song) <song.bao.hua@...ilicon.com>;
> > catalin.marinas@....com; will@...nel.org; rjw@...ysocki.net;
> > vincent.guittot@...aro.org; bp@...en8.de; tglx@...utronix.de;
> > mingo@...hat.com; lenb@...nel.org; peterz@...radead.org;
> > dietmar.eggemann@....com; rostedt@...dmis.org; bsegall@...gle.com;
> > mgorman@...e.de
> > Cc: msys.mizuma@...il.com; valentin.schneider@....com;
> > gregkh@...uxfoundation.org; Jonathan Cameron <jonathan.cameron@...wei.com>;
> > juri.lelli@...hat.com; mark.rutland@....com; sudeep.holla@....com;
> > aubrey.li@...ux.intel.com; linux-arm-kernel@...ts.infradead.org;
> > linux-kernel@...r.kernel.org; linux-acpi@...r.kernel.org; x86@...nel.org;
> > xuwei (O) <xuwei5@...wei.com>; Zengtao (B) <prime.zeng@...ilicon.com>;
> > guodong.xu@...aro.org; yangyicong <yangyicong@...wei.com>; Liguozhu
> (Kenneth)
> > <liguozhu@...ilicon.com>; linuxarm@...neuler.org; hpa@...or.com
> > Subject: Re: [RFC PATCH v5 4/4] scheduler: Add cluster scheduler level for
> x86
> >
> >
> >
> > On 3/18/21 9:16 PM, Barry Song wrote:
> > > From: Tim Chen <tim.c.chen@...ux.intel.com>
> > >
> > > There are x86 CPU architectures (e.g. Jacobsville) where L2 cahce
> > > is shared among a cluster of cores instead of being exclusive
> > > to one single core.
> > >
> > > To prevent oversubscription of L2 cache, load should be
> > > balanced between such L2 clusters, especially for tasks with
> > > no shared data.
> > >
> > > Also with cluster scheduling policy where tasks are woken up
> > > in the same L2 cluster, we will benefit from keeping tasks
> > > related to each other and likely sharing data in the same L2
> > > cluster.
> > >
> > > Add CPU masks of CPUs sharing the L2 cache so we can build such
> > > L2 cluster scheduler domain.
> > >
> > > Signed-off-by: Tim Chen <tim.c.chen@...ux.intel.com>
> > > Signed-off-by: Barry Song <song.bao.hua@...ilicon.com>
> >
> >
> > Barry,
> >
> > Can you also add this chunk to the patch.
> > Thanks.
> 
> Sure, Tim, Thanks. I'll put that into patch 4/4 in v6.

Hi Tim,
You might want to take a look at this qemu patchset:
https://lore.kernel.org/qemu-devel/20210331095343.12172-1-wangyanan55@huawei.com/T/#t

someone is trying to leverage this cluster topology
to improve KVM virtual machines performance.

> 
> >
> > Tim
> >
> >
> > diff --git a/arch/x86/include/asm/topology.h
> > b/arch/x86/include/asm/topology.h
> > index 2a11ccc14fb1..800fa48c9fcd 100644
> > --- a/arch/x86/include/asm/topology.h
> > +++ b/arch/x86/include/asm/topology.h
> > @@ -115,6 +115,7 @@ extern unsigned int __max_die_per_package;
> >
> >  #ifdef CONFIG_SMP
> >  #define topology_die_cpumask(cpu)		(per_cpu(cpu_die_map, cpu))
> > +#define topology_cluster_cpumask(cpu)		(cpu_clustergroup_mask(cpu))
> >  #define topology_core_cpumask(cpu)		(per_cpu(cpu_core_map, cpu))
> >  #define topology_sibling_cpumask(cpu)		(per_cpu(cpu_sibling_map, cpu))
> >
> 

Thanks
Barry