linux-kernel - Re: [RFC] [PATCH 0/5 V2] Huge page backed user-space stacks

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Message-ID: <87fxpi567v.fsf@basil.nowhere.org>
Date:	Wed, 06 Aug 2008 20:49:40 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Mel Gorman <mel@....ul.ie>, linuxppc-dev@...abs.org,
	libhugetlbfs-devel@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [RFC] [PATCH 0/5 V2] Huge page backed user-space stacks

Andrew Morton <akpm@...ux-foundation.org> writes:

> Do we expect that this change will be replicated in other
> memory-intensive apps?  (I do).

The catch with 2MB pages on x86 is that x86 CPUs generally have
much less 2MB TLB entries than 4K entries. So if you're unlucky
and access a lot of mappings you might actually thrash more with
them. That is why they are not necessarily an universal win.

-Andi
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