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

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Date:   Tue, 23 Mar 2021 15:50:49 -0700
From:   Tim Chen <tim.c.chen@...ux.intel.com>
To:     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@...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, xuwei5@...wei.com, prime.zeng@...ilicon.com,
        guodong.xu@...aro.org, yangyicong@...wei.com,
        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.

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))