From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1424009AbWKKPUd (ORCPT ); Sat, 11 Nov 2006 10:20:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1424010AbWKKPUd (ORCPT ); Sat, 11 Nov 2006 10:20:33 -0500 Received: from mx2.suse.de ([195.135.220.15]:44734 "EHLO mx2.suse.de") by vger.kernel.org with ESMTP id S1424009AbWKKPUc (ORCPT ); Sat, 11 Nov 2006 10:20:32 -0500 From: Andi Kleen To: Ingo Molnar Subject: Re: [patch] genapic: optimize & fix APIC mode setup Date: Sat, 11 Nov 2006 16:20:24 +0100 User-Agent: KMail/1.9.5 Cc: Andrew Morton , linux-kernel@vger.kernel.org, ashok.raj@intel.com References: <20061111151414.GA32507@elte.hu> In-Reply-To: <20061111151414.GA32507@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200611111620.24551.ak@suse.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Saturday 11 November 2006 16:14, Ingo Molnar wrote: > From: Ingo Molnar > > this patch fixes a couple of inconsistencies/problems i found while > reviewing the x86_64 genapic code (when i was chasing mysterious eth0 > timeouts that would only trigger if CPU_HOTPLUG is enabled): > > - AMD systems defaulted to the slower flat-physical mode instead > of the flat-logical mode. The only restriction on AMD systems > is that they should not use clustered APIC mode. This will open a race on CPU hotunplug unfortunately (common for multi core suspend) > > - removed the CPU hotplug hacks, switching the default for small > systems back from phys-flat to logical-flat. The switching to logical > flat mode on small systems fixed sporadic ethernet driver timeouts i > was getting on a dual-core Athlon64 system: That will break CPU hotplug on some Intel systems (Ashok can give details) That is caused ethernet timeouts is weird, probably needs to be root caused. > NETDEV WATCHDOG: eth0: transmit timed out > eth0: Transmit timeout, status 0c 0005 c07f media 80. > eth0: Tx queue start entry 32 dirty entry 28. > eth0: Tx descriptor 0 is 0008a04a. (queue head) > eth0: Tx descriptor 1 is 0008a04a. > eth0: Tx descriptor 2 is 0008a04a. > eth0: Tx descriptor 3 is 0008a04a. > eth0: link up, 100Mbps, full-duplex, lpa 0xC5E1 > > - The use of '<= 8' was a bug by itself (the valid APIC ids > for logical flat mode go from 0 to 7, not 0 to 8). The new logic > is to use logical flat mode on both AMD and Intel systems, and > to only switch to physical mode when logical mode cannot be used. > If CPU hotplug is racy wrt. APIC shutdown then CPU hotplug needs > fixing, not the whole IRQ system be made inconsistent and slowed > down. Yes that needs to be fixed. -Andi