From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id A1C6821161235 for ; Mon, 1 Oct 2018 14:54:59 -0700 (PDT) Subject: Re: [RFC workqueue/driver-core PATCH 1/5] workqueue: Provide queue_work_near to queue work near a given NUMA node References: <20180926214433.13512.30289.stgit@localhost.localdomain> <20180926215138.13512.33146.stgit@localhost.localdomain> <20180926215307.GA270328@devbig004.ftw2.facebook.com> <9b002bbb-3e6d-9e99-d8f9-36df4306093e@linux.intel.com> <20180926220957.GB270328@devbig004.ftw2.facebook.com> <20181001160142.GE270328@devbig004.ftw2.facebook.com> From: Alexander Duyck Message-ID: <4eebc017-23a2-a26e-095c-66433061a141@linux.intel.com> Date: Mon, 1 Oct 2018 14:54:39 -0700 MIME-Version: 1.0 In-Reply-To: <20181001160142.GE270328@devbig004.ftw2.facebook.com> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Tejun Heo Cc: len.brown@intel.com, linux-pm@vger.kernel.org, gregkh@linuxfoundation.org, linux-nvdimm@lists.01.org, jiangshanlai@gmail.com, linux-kernel@vger.kernel.org, zwisler@kernel.org, pavel@ucw.cz, rafael@kernel.org, akpm@linux-foundation.org List-ID: On 10/1/2018 9:01 AM, Tejun Heo wrote: > Hello, > > On Wed, Sep 26, 2018 at 03:19:21PM -0700, Alexander Duyck wrote: >> On 9/26/2018 3:09 PM, Tejun Heo wrote: >> I could just use queue_work_on probably, but is there any issue if I >> am passing CPU values that are not in the wq_unbound_cpumask? That > > That should be fine. If it can't find any available cpu, it'll fall > back to round-robin. We probably can improve it so that it can > consider the numa distance when falling back. > >> was mostly my concern. Also for an unbound queue do I need to worry >> about the hotplug lock? I wasn't sure if that was the case or not as > > Issuers don't need to worry about them. > >> I know it is called out as something to be concerned with using >> queue_work_on, but in __queue_work the value is just used to >> determine which node to grab a work queue from. > > It might be better to leave queue_work_on() to be used for per-cpu > workqueues and introduce queue_work_near() as you suggseted. I just > don't want it to duplicate the node selection code in it. Would that > work? So if I understand what you are saying correctly we default to round-robin on a given node has no CPUs attached to it. I could probably work with that if that is the default behavior instead of adding much of the complexity I already have. The question I have then is what should I do about workqueues that aren't WQ_UNBOUND if they attempt to use queue_work_near? In that case I should be looking for some way to go from a node to a CPU shouldn't I? If so should I look at doing something like wq_select_unbound_cpu that uses the node cpumask instead of the wq_unbound_cpumask? - Alex _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm