From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757441AbYBDXia (ORCPT ); Mon, 4 Feb 2008 18:38:30 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754570AbYBDXiV (ORCPT ); Mon, 4 Feb 2008 18:38:21 -0500 Received: from numenor.qualcomm.com ([129.46.51.58]:45020 "EHLO numenor.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753406AbYBDXiV (ORCPT ); Mon, 4 Feb 2008 18:38:21 -0500 Message-ID: <47A7A131.8040800@qualcomm.com> Date: Mon, 04 Feb 2008 15:35:13 -0800 From: Max Krasnyanskiy User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: LKML CC: Ingo Molnar , Daniel Walker Subject: CPU hotplug and IRQ affinity with 2.6.24-rt1 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is just an FYI. As part of the "Isolated CPU extensions" thread Daniel suggest for me to check out latest RT kernels. So I did or at least tried to and immediately spotted a couple of issues. The machine I'm running it on is: HP xw9300, Dual Opteron, NUMA It looks like with -rt kernel IRQ affinity masks are ignored on that system. ie I write 1 to lets say /proc/irq/23/smp_affinity but the interrupts keep coming to CPU1. Vanilla 2.6.24 does not have that issue. Also the first thing I tried was to bring CPU1 off-line. Thats the fastest way to get irqs, soft-irqs, timers, etc of a CPU. But the box hung completely. It also managed to mess up my ext3 filesystem to the point where it required manual fsck (have not see that for a couple of years now). I tried the same thing (ie echo 0 > /sys/devices/cpu/cpu1/online) from the console. It hang again with the message that looked something like: CPU1 is now off-line Thread IRQ-23 is on CPU1 ... IRQ 23 is NVidia SATA. So I guess it has something to do with the borked affinity handling. Vanilla 2.6.24 handles this just fine. Anyway, like I said it's just an FYI, not an urgent issue. Max