From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-pa0-f65.google.com ([209.85.220.65]:35837 "EHLO mail-pa0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751956AbcGRXvC (ORCPT ); Mon, 18 Jul 2016 19:51:02 -0400 Date: Mon, 18 Jul 2016 19:50:47 -0400 From: Tejun Heo To: Bhaktipriya Shridhar Cc: Mike Isely , Mauro Carvalho Chehab , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] [media] pvrusb2: Remove deprecated create_singlethread_workqueue Message-ID: <20160718235047.GS3078@mtj.duckdns.org> References: <20160716083234.GA7388@Karyakshetra> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160716083234.GA7388@Karyakshetra> Sender: linux-media-owner@vger.kernel.org List-ID: On Sat, Jul 16, 2016 at 02:02:34PM +0530, Bhaktipriya Shridhar wrote: > The workqueue "workqueue" is involved in polling the pvrusb2 hardware > (pvr2_hdw). > > It has a single work item(&hdw->workpoll) 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 pvr2_hdw_destroy to ensure that there are no > pending tasks while disconnecting the driver. > > Signed-off-by: Bhaktipriya Shridhar Acked-by: Tejun Heo Thanks. -- tejun