linux-kernel - Re: Big git diff speedup by avoiding x86 "fast string" memcmp

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Message-Id: <20101216.095716.71123831.davem@davemloft.net>
Date:	Thu, 16 Dec 2010 09:57:16 -0800 (PST)
From:	David Miller <davem@...emloft.net>
To:	bharrosh@...asas.com
Cc:	npiggin@...il.com, hooanon05@...oo.co.jp, npiggin@...nel.dk,
	torvalds@...ux-foundation.org, linux-arch@...r.kernel.org,
	x86@...nel.org, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org
Subject: Re: Big git diff speedup by avoiding x86 "fast string" memcmp

From: Boaz Harrosh <bharrosh@...asas.com>
Date: Thu, 16 Dec 2010 11:53:09 +0200

> You miss understood me. I'm saying that we know the beggining of the
> string is aligned and Nick offered to pad the last long, so surly
> a shift by 2 (or 3) + the reduction of the 12 dec-and-test to 3
> should give you an optimization?

Indeed, we could do something interesting in the case where both
strings are tail padded like that.
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