From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759433Ab0ECN12 (ORCPT ); Mon, 3 May 2010 09:27:28 -0400 Received: from casper.infradead.org ([85.118.1.10]:59044 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759302Ab0ECN1R convert rfc822-to-8bit (ORCPT ); Mon, 3 May 2010 09:27:17 -0400 Subject: Re: [PATCH 3/4] scheduler: replace migration_thread with cpu_stop From: Peter Zijlstra To: Tejun Heo Cc: mingo@elte.hu, linux-kernel@vger.kernel.org, x86@kernel.org, oleg@redhat.com, rusty@rustcorp.com.au, sivanich@sgi.com, heiko.carstens@de.ibm.com, dipankar@in.ibm.com, josh@freedesktop.org, paulmck@linux.vnet.ibm.com, akpm@linux-foundation.org, arjan@linux.intel.com, torvalds@linux-foundation.org In-Reply-To: <1271952554-22368-4-git-send-email-tj@kernel.org> References: <1271952554-22368-1-git-send-email-tj@kernel.org> <1271952554-22368-4-git-send-email-tj@kernel.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Mon, 03 May 2010 15:26:32 +0200 Message-ID: <1272893192.5605.122.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2010-04-22 at 18:09 +0200, Tejun Heo wrote: > @@ -2909,7 +2912,9 @@ redo: > } > raw_spin_unlock_irqrestore(&busiest->lock, flags); > if (active_balance) > - wake_up_process(busiest->migration_thread); > + stop_one_cpu_nowait(cpu_of(busiest), > + active_load_balance_cpu_stop, busiest, > + &busiest->active_balance_work); So who guarantees busiest->active_balance_work isn't already enqueued by some other cpu's load-balancer run?