From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH] mmc: rtsx: Remove deprecated create_singlethread_workqueue Date: Tue, 26 Jul 2016 13:02:12 -0400 Message-ID: <20160726170212.GA4144@mtj.duckdns.org> References: <20160726170106.GA10120@Karyakshetra> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20160726170106.GA10120@Karyakshetra> Sender: linux-kernel-owner@vger.kernel.org To: Bhaktipriya Shridhar Cc: Ulf Hansson , linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-mmc@vger.kernel.org On Tue, Jul 26, 2016 at 10:31:06PM +0530, Bhaktipriya Shridhar wrote: > The workqueue "workq" provides support for sd/mmc async request, which > makes next request do dma_map_sg() while previous request transferring > data. > > The workqueue has a single workitem(&host->work) 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 rtsx_pci_sdmmc_drv_remove() to ensure that > there are no pending tasks while disconnecting the driver. > > Signed-off-by: Bhaktipriya Shridhar Acked-by: Tejun Heo Thanks. -- tejun