linux-kernel - Re: [PATCH 0/5] Make cpuid <-> nodeid mapping persistent.

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Message-ID: <20150723183228.GR15934@mtj.duckdns.org>
Date:	Thu, 23 Jul 2015 14:32:28 -0400
From:	Tejun Heo <tj@...nel.org>
To:	Tang Chen <tangchen@...fujitsu.com>
Cc:	mingo@...hat.com, akpm@...ux-foundation.org, rjw@...ysocki.net,
	hpa@...or.com, laijs@...fujitsu.com, yasu.isimatu@...il.com,
	isimatu.yasuaki@...fujitsu.com, kamezawa.hiroyu@...fujitsu.com,
	izumi.taku@...fujitsu.com, gongzhaogang@...pur.com,
	qiaonuohan@...fujitsu.com, x86@...nel.org,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [PATCH 0/5] Make cpuid <-> nodeid mapping persistent.

Hello, Tang.

On Thu, Jul 23, 2015 at 12:44:53PM +0800, Tang Chen wrote:
> Allocating cpuid when a new cpu comes up and reusing the cpuid when it
> comes up again is possible. But I'm not quite sure if it will be less
> modification
> because we still need an array or bit map or something to keep the mapping,
> and select backup nodes for cpus on memory-less nodes when allocating
> memory.
> 
> I can post a set of patches for this idea. And then we can see which one is
> better.

I suspect the difference could be that in the current code the users
(workqueue) can remain the same while if we do it lazily there
probably needs to be a way to poke it.  As long as the IDs are
allocated to the online CPUs first, I think pre-allocating everything
should be fine too.

Thanks.

-- 
tejun
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