linux-kernel - Re: [PATCH 09/10] x86-32: use SSE for atomic64

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Message-ID: <1266488689.26719.114.camel@laptop>
Date:	Thu, 18 Feb 2010 11:24:49 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Luca Barbieri <luca@...a-barbieri.com>
Cc:	Andi Kleen <andi@...stfloor.org>, mingo@...e.hu, hpa@...or.com,
	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 09/10] x86-32: use SSE for atomic64_read/set if
 available

On Thu, 2010-02-18 at 10:53 +0100, Luca Barbieri wrote:
> perf is currently the main user.
> On Core2, lock cmpxchg8b takes about 24 cycles and writes the
> cacheline, while movlps takes 1 cycle. 

Then run a 64bit kernel already, then its a simple 1 cycle read.

The only platform this might possibly be worth the effort for it Atom,
the rest of the world has moved on to 64bit a long time ago.

There might still be a few pentium-m users out there that might
appreciate this too, but still..

That said, _iff_ this can be done nicely there's no objection.

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