linux-kernel - Re: [MM] Make mm counters per cpu instead of atomic

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Message-ID: <87r5se80oe.fsf@basil.nowhere.org>
Date:	Wed, 04 Nov 2009 22:01:05 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Christoph Lameter <cl@...ux-foundation.org>
Cc:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	"hugh.dickins@...cali.co.uk" <hugh.dickins@...cali.co.uk>,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org, Tejun Heo <tj@...nel.org>
Subject: Re: [MM] Make mm counters per cpu instead of atomic

Christoph Lameter <cl@...ux-foundation.org> writes:
>
> One price to pay for these improvements is the need to scan over all percpu
> counters when the actual count values are needed.

Do you have numbers how costly alloc_percpu() is? I wonder what this
does to fork() overhead.

-Andi
 

-- 
ak@...ux.intel.com -- Speaking for myself only.
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