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From: "Huang, Ying" <ying.huang@intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: <linux-kernel@vger.kernel.org>,
	Valentin Schneider <valentin.schneider@arm.com>,
	Ingo Molnar <mingo@redhat.com>, Mel Gorman <mgorman@suse.de>,
	Rik van Riel <riel@surriel.com>,
	Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Subject: Re: [PATCH -V3 2/2 UPDATE] NUMA balancing: avoid to migrate task to CPU-less node
Date: Tue, 08 Mar 2022 10:11:11 +0800	[thread overview]
Message-ID: <87tuc9kxc0.fsf@yhuang6-desk2.ccr.corp.intel.com> (raw)
In-Reply-To: <87y21lkxlv.fsf_-_@yhuang6-desk2.ccr.corp.intel.com> (Ying Huang's message of "Tue, 08 Mar 2022 10:05:16 +0800")

Hi, Peter,

"Huang, Ying" <ying.huang@intel.com> writes:

> In a typical memory tiering system, there's no CPU in slow (PMEM) NUMA
> nodes.  But if the number of the hint page faults on a PMEM node is
> the max for a task, The current NUMA balancing policy may try to place
> the task on the PMEM node instead of DRAM node.  This is unreasonable,
> because there's no CPU in PMEM NUMA nodes.  To fix this, CPU-less
> nodes are ignored when searching the migration target node for a task
> in this patch.
>
> To test the patch, we run a workload that accesses more memory in PMEM
> node than memory in DRAM node.  Without the patch, the PMEM node will
> be chosen as preferred node in task_numa_placement().  While the DRAM
> node will be chosen instead with the patch.
>
> Known issue: I don't have systems to test complex NUMA topology type,
> for example, NUMA_BACKPLANE or NUMA_GLUELESS_MESH.
>
> v3:
>
> - Fix a boot crash for some uncovered marginal condition.  Thanks Qian
>   Cai for reporting and testing the bug!
>
> - Fix several missing places to use CPU-less nodes as migrating
>   target.
>
> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
> Reported-and-tested-by: Qian Cai <quic_qiancai@quicinc.com> # boot crash
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Valentin Schneider <valentin.schneider@arm.com>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Mel Gorman <mgorman@suse.de>
> Cc: Rik van Riel <riel@surriel.com>
> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

Can you update the patch to fix the bug?  Or you prefer the incremental
patch?

Best Regards,
Huang, Ying

  reply	other threads:[~2022-03-08  2:11 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-14 12:15 [PATCH -V3 1/2] NUMA balancing: fix NUMA topology for systems with CPU-less nodes Huang Ying
2022-02-14 12:15 ` [PATCH -V3 2/2] NUMA balancing: avoid to migrate task to CPU-less node Huang Ying
2022-02-17 18:56   ` [tip: sched/core] sched/numa: Avoid migrating " tip-bot2 for Huang Ying
2022-03-01 20:54     ` Qian Cai
2022-03-01 20:54       ` Qian Cai
2022-03-02  0:59       ` Huang, Ying
2022-03-02  0:59         ` Huang, Ying
2022-03-02 12:37         ` Qian Cai
2022-03-02 12:37           ` Qian Cai
2022-03-07  5:51         ` Huang, Ying
2022-03-07  5:51           ` Huang, Ying
2022-03-07 13:53           ` Qian Cai
2022-03-07 13:53             ` Qian Cai
2022-03-08  0:40             ` Huang, Ying
2022-03-08  0:40               ` Huang, Ying
2022-03-08  2:05   ` [PATCH -V3 2/2 UPDATE] NUMA balancing: avoid to migrate " Huang, Ying
2022-03-08  2:11     ` Huang, Ying [this message]
2022-03-16  0:37       ` Huang, Ying
2022-02-14 15:05 ` [PATCH -V3 1/2] NUMA balancing: fix NUMA topology for systems with CPU-less nodes Peter Zijlstra
2022-02-15  1:29   ` Huang, Ying
2022-02-17 18:56 ` [tip: sched/core] sched/numa: Fix " tip-bot2 for Huang Ying

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