From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965208AbVHPNQA (ORCPT ); Tue, 16 Aug 2005 09:16:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965209AbVHPNQA (ORCPT ); Tue, 16 Aug 2005 09:16:00 -0400 Received: from ns2.suse.de ([195.135.220.15]:56223 "EHLO mx2.suse.de") by vger.kernel.org with ESMTP id S965208AbVHPNP7 (ORCPT ); Tue, 16 Aug 2005 09:15:59 -0400 To: Arjan van de Ven Cc: taka@valinux.co.jp, linux-kernel@vger.kernel.org Subject: Re: [RFC] [PATCH] cache pollution aware __copy_from_user_ll() References: <20050816.131729.15816429.taka@valinux.co.jp.suse.lists.linux.kernel> <20050816.135425.719901536.hyoshiok@miraclelinux.com.suse.lists.linux.kernel> <1124171015.3215.0.camel@laptopd505.fenrus.org.suse.lists.linux.kernel> <20050816.191617.1025215458.hyoshiok@miraclelinux.com.suse.lists.linux.kernel> <1124187950.3215.31.camel@laptopd505.fenrus.org.suse.lists.linux.kernel> From: Andi Kleen Date: 16 Aug 2005 15:15:35 +0200 In-Reply-To: <1124187950.3215.31.camel@laptopd505.fenrus.org.suse.lists.linux.kernel> Message-ID: User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Arjan van de Ven writes: > > not on kernel entry afaik. > However just save the register on the stack and put it back at the > end... You need to do more than that, like disabling lazy FPU mode. That is what kernel_fpu_begin/end takes care of. However it disables preemption, which especially for bigger copies will probably make the low latency people unhappy. Without disabling preemption there is no way to use SSE right now. Note that there is also an integer NT store in SSE1, however at least in Athlon K7 it is microcoded and very slow. -Andi