From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S269299AbUHaXLa (ORCPT ); Tue, 31 Aug 2004 19:11:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S269306AbUHaXLa (ORCPT ); Tue, 31 Aug 2004 19:11:30 -0400 Received: from zero.aec.at ([193.170.194.10]:39940 "EHLO zero.aec.at") by vger.kernel.org with ESMTP id S269299AbUHaXKH (ORCPT ); Tue, 31 Aug 2004 19:10:07 -0400 To: Ingo Molnar cc: linux-kernel@vger.kernel.org Subject: Re: [patch] voluntary-preempt-2.6.9-rc1-bk4-Q5 References: <2yQkS-6Zh-13@gated-at.bofh.it> <2zaCV-4FE-3@gated-at.bofh.it> <2zaWk-4Yj-9@gated-at.bofh.it> <2zmE8-4Zz-11@gated-at.bofh.it> <2zngP-5wD-9@gated-at.bofh.it> <2zngP-5wD-7@gated-at.bofh.it> <2znJS-5Pm-25@gated-at.bofh.it> <2znJS-5Pm-27@gated-at.bofh.it> <2znJS-5Pm-29@gated-at.bofh.it> <2znJS-5Pm-31@gated-at.bofh.it> <2znJS-5Pm-33@gated-at.bofh.it> From: Andi Kleen Date: Wed, 01 Sep 2004 01:10:04 +0200 In-Reply-To: <2znJS-5Pm-33@gated-at.bofh.it> (Ingo Molnar's message of "Wed, 01 Sep 2004 00:00:20 +0200") Message-ID: User-Agent: Gnus/5.110003 (No Gnus v0.3) Emacs/21.2 (gnu/linux) 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 Ingo Molnar writes: > * Ingo Molnar wrote: > >> >> * Lee Revell wrote: >> >> > File under boot-time stuff, I guess. This could be bad if X crashes, >> > but I can't remember the last time this happened to me, and I use xorg >> > CVS. >> >> but the first wbinvd() within prepare_set() seems completely unnecessary >> - we can flush the cache after disabling the cache just fine. > > the third wbinvd() in post_set() seems unnecessary too - what kind of > cache do we expect to flush, we've disabled caching in the CPU ... But > the Intel pseudocode does it too - this is a thinko i think. The multiple steps are needed, otherwise there can be problems with hyperthreading (the first x86-64 didn't do it in all cases, and it causes occassional problens with Intel CPUs) Also repeated calls of this are relatively cheap because at the second time there is not much to flush anymore. I would suggest to not do this change, it could cause very subtle problems. -Andi