From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752994Ab2GTQkU (ORCPT ); Fri, 20 Jul 2012 12:40:20 -0400 Received: from merlin.infradead.org ([205.233.59.134]:48530 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752420Ab2GTQkS convert rfc822-to-8bit (ORCPT ); Fri, 20 Jul 2012 12:40:18 -0400 Message-ID: <1342802391.2583.11.camel@twins> Subject: Re: [PATCHSET] workqueue: reimplement CPU hotplug to keep idle workers From: Peter Zijlstra To: Tejun Heo Cc: linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, tglx@linutronix.de, linux-pm@vger.kernel.org Date: Fri, 20 Jul 2012 18:39:51 +0200 In-Reply-To: <1342545149-3515-1-git-send-email-tj@kernel.org> References: <1342545149-3515-1-git-send-email-tj@kernel.org> 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 Tue, 2012-07-17 at 10:12 -0700, Tejun Heo wrote: > Currently, workqueue destroys all workers for offline CPUs unless > there are lingering work items. _that_ is the root of all ugly in that thing. I still find it utterly insane you can create 'per-cpu' workqueues and then violate the per-cpu property with hotplug and get your work ran on a different CPU. It should be a hard error to use queue_work_on() and then run the work on a different cpu. Yet somehow this isn't so.