linux-kernel - Re: [PATCH v2 2/3] sched/fair: Ignore isolated cpus in update_numa

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Message-ID: <c03e21a0-7b7d-40ca-b1e8-71c4c3d59525@linux.ibm.com>
Date: Mon, 6 Jan 2025 00:22:26 +0530
From: Madadi Vineeth Reddy <vineethr@...ux.ibm.com>
To: Chuyi Zhou <zhouchuyi@...edance.com>
Cc: mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        vschneid@...hat.com, longman@...hat.com, riel@...riel.com,
        chengming.zhou@...ux.dev, kprateek.nayak@....com,
        linux-kernel@...r.kernel.org,
        Madadi Vineeth Reddy <vineethr@...ux.ibm.com>
Subject: Re: [PATCH v2 2/3] sched/fair: Ignore isolated cpus in
 update_numa_stat

On 03/01/25 12:29, Chuyi Zhou wrote:
> Now update_numa_stats() iterates each cpu in a node to gather load
> information for the node and attempts to find the idle cpu as a candidate
> best_cpu within the node.
> 
> In update_numa_stats() we should take into account the scheduling domain.
> This is because the "isolcpus" kernel command line option and cpuset iso-
> late partitions can remove CPUs from load balance. Similar to task wakeup
> and periodic load balancing, we should not involve isolated CPUs in NUMA
> balancing. When gathering load information for nodes, we need to ignore the
> load of isolated CPUs. This change also avoids selecting an isolated CPU
> as the idle_cpu.

If possible, would you be able to share any performance metrics or benchmarks
that demonstrate the impact of this patch on NUMA balancing or CPU migration
efficiency?

Thanks,
Madadi Vineeth Reddy

> 
> Signed-off-by: Chuyi Zhou <zhouchuyi@...edance.com>
> ---
>  kernel/sched/fair.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)