From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yw0-x243.google.com (mail-yw0-x243.google.com [IPv6:2607:f8b0:4002:c05::243]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3sPSLJ6GcrzDrhc for ; Thu, 1 Sep 2016 00:23:52 +1000 (AEST) Received: by mail-yw0-x243.google.com with SMTP id j12so1995261ywb.1 for ; Wed, 31 Aug 2016 07:23:52 -0700 (PDT) Sender: Tejun Heo Date: Wed, 31 Aug 2016 10:23:48 -0400 From: Tejun Heo To: Bhaktipriya Shridhar Cc: Geoff Levand , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ps3: Remove deprecated create_singlethread_workqueue Message-ID: <20160831142348.GJ12660@htj.duckdns.org> References: <20160830171450.GA1890@Karyakshetra> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20160830171450.GA1890@Karyakshetra> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, Aug 30, 2016 at 10:44:51PM +0530, Bhaktipriya Shridhar wrote: > The workqueue "ps3av->wq" queues a single work item &ps3av->work and hence > doesn't require ordering. It is involved in waking up ps3avd to do the > video mode setting and hence it's not being used on a memory reclaim > path. Hence, it has been converted to use 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. > > The work item has been flushed in ps3av_remove to ensure that > there are no pending tasks while disconnecting the driver. > > Signed-off-by: Bhaktipriya Shridhar Acked-by: Tejun Heo Thanks. -- tejun