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

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Message-ID: <20100218202627.GH5964@basil.fritz.box>
Date:	Thu, 18 Feb 2010 21:26:27 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Luca Barbieri <luca@...a-barbieri.com>
Cc:	"H. Peter Anvin" <hpa@...or.com>, Andi Kleen <andi@...stfloor.org>,
	mingo@...e.hu, a.p.zijlstra@...llo.nl, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 09/10] x86-32: use SSE for atomic64_read/set if
	available

> memcpy/memset/etc. (assuming SSE is the best option for these at least
> on some processors) and checksums come to mind.

Typically SSE advantages only come to play with very large data sets,
and the kernel's are not big enough. I tried it some time ago.

That said you can already use kernel_fpu_begin/end of course
and it's used in some very rare cases.

> Also non-temporal SSE moves might be useful for things like memory
> compaction without clobbering caches.

You don't need SSE for non temporal moves.

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only.
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