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Date: Wed, 18 Aug 2004 09:00:13 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Jens Maurer <Jens.Maurer@gmx.net>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>, Andrew Morton <akpm@osdl.org>,
       Arjan van de Ven <arjanv@redhat.com>
Subject: Re: [PATCH] Use x86 SSE instructions for clear_page, copy_page
Message-ID: <20040818070013.GA11048@elte.hu>
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* Jens Maurer <Jens.Maurer@gmx.net> wrote:

> The attached patch (against kernel 2.6.8.1) enables using SSE
> instructions for copy_page and clear_page.

besides the cache arguments Arjan raised, you are also corrupting SSE
registers big way. You are saving/clearing/restoring the TS but that's
not enough - what if e.g. a pagefault happened while userspace code
executed SSE code? You are corrupting those registers.

check out raid6_before_sse()/raid6_after_sse() how to write proper SSE
code for the kernel.

	Ingo