Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S268227AbUISOHM (ORCPT ); Sun, 19 Sep 2004 10:07:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S269075AbUISOHM (ORCPT ); Sun, 19 Sep 2004 10:07:12 -0400 Received: from natnoddy.rzone.de ([81.169.145.166]:47554 "EHLO natnoddy.rzone.de") by vger.kernel.org with ESMTP id S268227AbUISOHL (ORCPT ); Sun, 19 Sep 2004 10:07:11 -0400 Date: Sun, 19 Sep 2004 16:07:38 +0200 From: Dominik Brodowski To: mingo@redhat.com Cc: linux-kernel@vger.kernel.org Subject: boot_cpu_data vs current_cpu_data in voluntary-preempt-2.6.9-rc2-mm1-S1 Message-ID: <20040919140738.GA8327@dominikbrodowski.de> Mail-Followup-To: Dominik Brodowski , mingo@redhat.com, linux-kernel@vger.kernel.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.6i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1016 Lines: 28 Ingo, Your voluntary-preempt-2.6.9-rc2-mm1-S1 patch contains this change @@ -34,7 +34,7 @@ inline void __const_udelay(unsigned long xloops *= 4; __asm__("mull %0" :"=d" (xloops), "=&a" (d0) - :"1" (xloops),"0" (current_cpu_data.loops_per_jiffy * (HZ/4))); + :"1" (xloops),"0" (boot_cpu_data.loops_per_jiffy * (HZ/4))); __delay(++xloops); } for both x86 and x86_64. And it's wrong. It assumes loops_per_jiffy being consistent on all CPUs. There _are_ asymetric multiprocessor systems out there, and some SMP systems can become asymetric as soon as frequency scaling is enabled. Using boot_cpu_data's loops_per_jiffy instead of current_cpu_data's loops_per_jiffy causes delays being too short or too long. So please drop this change. Thanks, Dominik - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/