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 BFDE32115C07A for ; Tue, 2 Oct 2018 13:49:22 -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> <4eebc017-23a2-a26e-095c-66433061a141@linux.intel.com> <20181002174116.GG270328@devbig004.ftw2.facebook.com> <20181002184127.GH270328@devbig004.ftw2.facebook.com> From: Alexander Duyck Message-ID: <92d8b57f-db37-e4bf-b69f-3ab5c4440ea0@linux.intel.com> Date: Tue, 2 Oct 2018 13:49:22 -0700 MIME-Version: 1.0 In-Reply-To: <20181002184127.GH270328@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 10/2/2018 11:41 AM, Tejun Heo wrote: > Hello, > > On Tue, Oct 02, 2018 at 11:23:26AM -0700, Alexander Duyck wrote: >>> Yeah, it's all in wq_select_unbound_cpu(). Right now, if the >>> requested cpu isn't in wq_unbound_cpumask, it falls back to dumb >>> round-robin. We can probably do better there and find the nearest >>> node considering topology. >> >> Well if we could get wq_select_unbound_cpu doing the right thing >> based on node topology that would be most of my work solved right >> there. Basically I could just pass WQ_CPU_UNBOUND with the correct >> node and it would take care of getting to the right CPU. > > Yeah, sth like that. It might be better to keep the function to take > cpu for consistency as everything else passes around cpu. > >>>> 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 >>> >>> Hmm... yeah, let's just use queue_work_on() for now. We can sort it >>> out later and users could already do that anyway. >> >> So are you saying I should just return an error for now if somebody >> tries to use something other than an unbound workqueue with >> queue_work_near, and expect everyone else to just use queue_work_on >> for the other workqueue types? > > Oh, I meant that let's not add a new interface for now and just use > queue_work_on() for your use case too. > > Thanks. So the only issue is that I was hoping to get away with not having to add additional preemption. That was the motivation behind doing queue_work_near as I could just wrap it all in the same local_irq_save that way I don't have to worry about the CPU I am on changing. What I may look at doing is just greatly reducing the workqueue_select_unbound_cpu_near function to essentially just perform a few tests and then will just use the results from a cpumask_any_and of the cpumask_of_node and the cpu_online_mask. I'll probably rename it while I am at it since I am going to probably be getting away from the "unbound" checks in the logic. - Alex _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm