From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752334AbcGBN6y (ORCPT ); Sat, 2 Jul 2016 09:58:54 -0400 Received: from mail-it0-f65.google.com ([209.85.214.65]:33843 "EHLO mail-it0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751417AbcGBN6w (ORCPT ); Sat, 2 Jul 2016 09:58:52 -0400 Date: Sat, 2 Jul 2016 09:41:10 -0400 From: Tejun Heo To: Bhaktipriya Shridhar Cc: Hans Verkuil , Mauro Carvalho Chehab , Arnd Bergmann , Markus Elfring , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] [media] hdpvr: Remove deprecated create_singlethread_workqueue Message-ID: <20160702134110.GW17431@htj.duckdns.org> References: <20160702104731.GA2358@Karyakshetra> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160702104731.GA2358@Karyakshetra> User-Agent: Mutt/1.6.1 (2016-04-27) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jul 02, 2016 at 04:17:31PM +0530, Bhaktipriya Shridhar wrote: > The workqueue "workqueue" is involved in tranmitting hdpvr buffers. > It has a single work item(&dev->worker) and hence doesn't require > ordering. Also, it is not being used on a memory reclaim path. Hence, > the singlethreaded workqueue has been replaced with the use of system_wq. > > System workqueues have been able to handle high level of concurrency > for a long time now and hence it's not required to have a singlethreaded > workqueue just to gain concurrency. Unlike a dedicated per-cpu workqueue > created with create_singlethread_workqueue(), system_wq allows multiple > work items to overlap executions even on the same CPU; however, a > per-cpu workqueue doesn't have any CPU locality or global ordering > guarantee unless the target CPU is explicitly specified and thus the > increase of local concurrency shouldn't make any difference. > > Work item has been flushed in hdpvr_device_release() to ensure > that there are no pending tasks while disconnecting the driver. > > Signed-off-by: Bhaktipriya Shridhar Acked-by: Tejun Heo Thanks. -- tejun