From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964916Ab2CATGq (ORCPT ); Thu, 1 Mar 2012 14:06:46 -0500 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:11468 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756064Ab2CATDr (ORCPT ); Thu, 1 Mar 2012 14:03:47 -0500 X-Authority-Analysis: v=2.0 cv=Xp94yC59 c=1 sm=0 a=ZycB6UtQUfgMyuk2+PxD7w==:17 a=XQbtiDEiEegA:10 a=UBy9sU4F98IA:10 a=3agwfarryv0A:10 a=5SG0PmZfjMsA:10 a=bbbx4UPp9XUA:10 a=ZSBtEVsvCWZWRKQE_cUA:9 a=ZycB6UtQUfgMyuk2+PxD7w==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.67.80.29 Message-Id: <20120301185527.064629423@goodmis.org> User-Agent: quilt/0.50-1 Date: Thu, 01 Mar 2012 13:55:27 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-rt-users Cc: Thomas Gleixner , Carsten Emde , John Kacur , Peter Zijlstra , Clark Williams Subject: [PATCH RT 0/9][RFC] rt: Fix hotplugging and other nasties Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On both 3.0-rt and 3.2-rt I ran a stress test on CPU hotplug and they both failed miserably. These bugs also show themselves on suspend. After spending 5 long days debugging this, and finding lots of bugs I have a patch series that makes the CPU hot plugging rather stable. The first few patches fix other broken RT features that were discovered while debugging hotplug. Patch 7 is a rework of how RT handles taking down a CPU. There were several corner cases that the original approach failed on, and this rework seems to cover them now. Patch 8 and 9 revert the rework that was done on workqueue for RT. Yes, letting workqueues play games with THREAD_BOUND is bad, but the fixes introduced several more races that were very hard to fix. Every fix seemed to produce a new race, and it was a bad game of cat and mouse running around a goose hunt whacking moles! Since the rework of the CPU down code no longer had issues with workqueue messing with THREAD_BOUND, reverting the patches that did the rework of workqueues fixed the bugs that I was hitting. Lets fix CPU hotplug today, and leave the redesign of workqueues for another day. Comments, -- Steve