From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755473AbYHSRQs (ORCPT ); Tue, 19 Aug 2008 13:16:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752614AbYHSRQk (ORCPT ); Tue, 19 Aug 2008 13:16:40 -0400 Received: from gv-out-0910.google.com ([216.239.58.190]:17269 "EHLO gv-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752421AbYHSRQj (ORCPT ); Tue, 19 Aug 2008 13:16:39 -0400 Message-ID: <48AAFFF0.7020405@colorfullife.com> Date: Tue, 19 Aug 2008 19:16:32 +0200 From: Manfred Spraul User-Agent: Thunderbird 2.0.0.16 (X11/20080723) MIME-Version: 1.0 To: paulmck@linux.vnet.ibm.com, mingo@elte.hu CC: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, oleg@tv-sign.ru, dipankar@in.ibm.com, rostedt@goodmis.org, dvhltc@us.ibm.com, niv@us.ibm.com Subject: nohz_cpu_mask question (was: Re: [PATCH tip/core/rcu] classic RCU locking and memory-barrier cleanups) References: <20080805162144.GA8297@linux.vnet.ibm.com> <489936E5.7020509@colorfullife.com> <20080807031806.GA6910@linux.vnet.ibm.com> <48A93D49.2000601@colorfullife.com> <20080818140404.GD6847@linux.vnet.ibm.com> <48AAA501.8010502@colorfullife.com> <20080819140339.GF7106@linux.vnet.ibm.com> In-Reply-To: <20080819140339.GF7106@linux.vnet.ibm.com> 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 Hi all, can someone explain me nohz_cpu_mask? If I understand it correctly, it merely means that this cpu does not take timer interrupts, correct? The cpu can still take "real" interupts, e.g. a nic interrupt. The cpu could also do softirq processing. Is that correct? Ingo? If nohz cpus can take normal interrupts, then it would be wrong to exclude these cpus from the mask of cpus that must pass a quiescent cycle - a softirq could hold on a pointers. -- Manfred