From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757752Ab2B2LDT (ORCPT ); Wed, 29 Feb 2012 06:03:19 -0500 Received: from merlin.infradead.org ([205.233.59.134]:48151 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751653Ab2B2LDS convert rfc822-to-8bit (ORCPT ); Wed, 29 Feb 2012 06:03:18 -0500 Message-ID: <1330513384.11248.129.camel@twins> Subject: Re: RFC [PATCH] SMP: Don't schedule tasks on inactive cpu(s) From: Peter Zijlstra To: Jonas Aaberg Cc: linux-kernel@vger.kernel.org, Russell King , Linus Walleij , Thomas Gleixner Date: Wed, 29 Feb 2012 12:03:04 +0100 In-Reply-To: <1330512150-20727-1-git-send-email-jonas.aberg@stericsson.com> References: <1330512150-20727-1-git-send-email-jonas.aberg@stericsson.com> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Mailer: Evolution 3.2.2- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2012-02-29 at 11:42 +0100, Jonas Aaberg wrote: > This patch removes the ability to schedule tasks on cpus that are online, > but not active. The reason for this patch is that during cpu hotplug > on ARM (atleast) there is a short window where cpuX (X > 0) is online, but > busy-waiting on cpu0 to put it active, meanwhile cpu0 can be interrupted > and try to schedule something on the cpu that is busy checking its active bit. https://lkml.org/lkml/2011/12/15/255 that one? I _think_ its correct, but it would be so good if someone else could verify.