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From: Andrew Morton <akpm@linux-foundation.org>
To: Wei Yang <richardw.yang@linux.intel.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	rientjes@google.com, mhocko@kernel.org
Subject: Re: [Patch v4] mm/vmscan.c: remove cpu online notification for now
Date: Wed, 19 Feb 2020 12:08:10 -0800	[thread overview]
Message-ID: <20200219120810.c7677fa58594f5423549f59d@linux-foundation.org> (raw)
In-Reply-To: <20200218224422.3407-1-richardw.yang@linux.intel.com>

On Wed, 19 Feb 2020 06:44:22 +0800 Wei Yang <richardw.yang@linux.intel.com> wrote:

> kswapd kernel thread starts either with a CPU affinity set to the full
> cpu mask of its target node or without any affinity at all if the node
> is CPUless. There is a cpu hotplug callback (kswapd_cpu_online) that
> implements an elaborate way to update this mask when a cpu is onlined.
> 
> It is not really clear whether there is any actual benefit from this
> scheme. Completely CPU-less NUMA nodes rarely gain a new CPU during
> runtime.

This is the case across all platforms, all architectures, all users for
the next N years?  I'm surprised that we know this with sufficient
confidence.  Can you explain how you came to make this assertion?

> Drop the code for that reason. If there is a real usecase then
> we can resurrect and simplify the code.


  reply	other threads:[~2020-02-19 20:08 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-18 22:44 [Patch v4] mm/vmscan.c: remove cpu online notification for now Wei Yang
2020-02-19 20:08 ` Andrew Morton [this message]
2020-02-20  7:52   ` Michal Hocko
2020-02-20 17:03     ` Yang Shi

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