From mboxrd@z Thu Jan  1 00:00:00 1970
From: Dmitry Potapov <dpotapov@gmail.com>
Subject: Re: [PATCH] Teach "git add" and friends to be paranoid
Date: Mon, 22 Feb 2010 16:33:27 +0300
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Cc: Junio C Hamano <gitster@pobox.com>,
	Nicolas Pitre <nico@fluxnic.net>, Jeff King <peff@peff.net>,
	Zygo Blaxell <zblaxell@esightcorp.com>,
	Ilari Liusvaara <ilari.liusvaara@elisanet.fi>,
	Thomas Rast <trast@student.ethz.ch>,
	Jonathan Nieder <jrnieder@gmail.com>, git@vger.kernel.org
To: Paolo Bonzini <bonzini@gnu.org>
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On Mon, Feb 22, 2010 at 01:59:50PM +0100, Paolo Bonzini wrote:
> On 02/18/2010 06:36 AM, Junio C Hamano wrote:
> >
> >In any case, with any size of paranoia, this hurts the sane use case
> 
> Because by mmaping + memcpying you are getting the worst of both
> cases: you get a page fault per page like with mmap, and touch
> memory twice like with read.

and there is also an extra round of SHA-1 calculation, which I believe
is more expensive than memcpy().


Dmitry