From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933438AbeAIPiB (ORCPT + 1 other); Tue, 9 Jan 2018 10:38:01 -0500 Received: from mail-qk0-f172.google.com ([209.85.220.172]:45041 "EHLO mail-qk0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933395AbeAIPh5 (ORCPT ); Tue, 9 Jan 2018 10:37:57 -0500 X-Google-Smtp-Source: ACJfBosrXx57u9do3Y0oI6QQMUPP9L8ucvBZdYxl1MKDM7kQAMnwLLidqniW4geOnvHMPa7wuHDcyg== Date: Tue, 9 Jan 2018 07:37:52 -0800 From: Tejun Heo To: "Paul E. McKenney" Cc: Prateek Sood , Peter Zijlstra , avagin@gmail.com, mingo@kernel.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, sramana@codeaurora.org Subject: Re: [PATCH] cgroup/cpuset: fix circular locking dependency Message-ID: <20180109153752.GI3668920@devbig577.frc2.facebook.com> References: <20180102161656.GD3668920@devbig577.frc2.facebook.com> <20180102174408.GM7829@linux.vnet.ibm.com> <20180102180119.GA1355@linux.vnet.ibm.com> <20180108122823.GL3668920@devbig577.frc2.facebook.com> <20180108225238.GN9671@linux.vnet.ibm.com> <20180109003127.GA30224@linux.vnet.ibm.com> <20180109034211.GC3668920@devbig577.frc2.facebook.com> <20180109042016.GR9671@linux.vnet.ibm.com> <20180109134448.GE3668920@devbig577.frc2.facebook.com> <20180109152112.GT9671@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180109152112.GT9671@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: Hello, Paul. On Tue, Jan 09, 2018 at 07:21:12AM -0800, Paul E. McKenney wrote: > > The code was previously using both system_power_efficient_wq and > > system_workqueue (for the expedited path). I guess the options were > > either using two workqueues or dropping POWER_EFFICIENT. I have no > > idea how big an impact this will make or whether it'd even be > > noticeable but maybe it'd be worthwhile to mention that in the > > description? > > Good point! How about if I change the last paragraph of the commit > log to read as follows? > > Thanx, Paul > > ------------------------------------------------------------------------ > > This commit also causes SRCU to use this new RCU-specific > workqueue_struct. Note that SRCU's use of workqueues never blocks them > waiting for readers, so this should be safe from a forward-progress > viewpoint. Note that this moves SRCU from system_power_efficient_wq > to a normal workqueue. In the unlikely event that this results in > measurable degradation, a separate power-efficient workqueue will be > creates for SRCU. Sounds good. Please feel free to add Acked-by: Tejun Heo Thanks. -- tejun