Message-ID: <3EBC29E5.3030002@zytor.com>
Date: Fri, 09 May 2003 15:21:25 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
Organization: Zytor Communications
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To: Ulrich Drepper <drepper@redhat.com>
CC: linux-kernel@vger.kernel.org
Subject: Re: hammer: MAP_32BIT
References: <3EBB5A44.7070704@redhat.com> <20030509092026.GA11012@averell> <16059.37067.925423.998433@gargle.gargle.HOWL> <20030509113845.GA4586@averell> <b9gr03$42n$1@cesium.transmeta.com> <3EBC0084.4090809@redhat.com> <3EBC15B5.4070604@zytor.com> <3EBC2164.6050605@redhat.com> <3EBC26BF.2080709@zytor.com> <3EBC29AD.5050203@redhat.com>
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Ulrich Drepper wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
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> 
> H. Peter Anvin wrote:
> 
>>On the other
>>hand, how big of a performance issue is it really to call mmap() again
>>in the failure scenario *only*?
> 
> 
> Just look at the code, it's very expensive.  In the moment the mmap code
> has to sequentially look at the VMAs in question.  If it fails it means
> it walked the entire data structure without success.  Ingo's patch does
> not address this, it just makes successful allocation usually fast again.
> 

OK, maybe we should fix that instead :-/

	-hpa


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