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Subject: Re: [RFC PATCH v5 4/4] scheduler: Add cluster scheduler level for x86
To:     Barry Song <song.bao.hua@hisilicon.com>, catalin.marinas@arm.com,
        will@kernel.org, rjw@rjwysocki.net, vincent.guittot@linaro.org,
        bp@alien8.de, tglx@linutronix.de, mingo@redhat.com,
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Cc:     msys.mizuma@gmail.com, valentin.schneider@arm.com,
        gregkh@linuxfoundation.org, jonathan.cameron@huawei.com,
        juri.lelli@redhat.com, mark.rutland@arm.com, sudeep.holla@arm.com,
        aubrey.li@linux.intel.com, linux-arm-kernel@lists.infradead.org,
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        guodong.xu@linaro.org, yangyicong@huawei.com,
        liguozhu@hisilicon.com, linuxarm@openeuler.org, hpa@zytor.com
References: <20210319041618.14316-1-song.bao.hua@hisilicon.com>
 <20210319041618.14316-5-song.bao.hua@hisilicon.com>
From:   Tim Chen <tim.c.chen@linux.intel.com>
Message-ID: <110234d1-22ce-8a9a-eabb-c15ac29a5dcd@linux.intel.com>
Date:   Tue, 23 Mar 2021 15:50:49 -0700
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On 3/18/21 9:16 PM, Barry Song wrote:
> From: Tim Chen <tim.c.chen@linux.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@linux.intel.com>
> Signed-off-by: Barry Song <song.bao.hua@hisilicon.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))