From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH 06/13] irq: add a helper spread an affinity mask for MSI/MSI-X vectors To: "Guilherme G. Piccoli" , Christoph Hellwig References: <1465934346-20648-1-git-send-email-hch@lst.de> <1465934346-20648-7-git-send-email-hch@lst.de> <57607D0E.1060907@linux.vnet.ibm.com> From: Bart Van Assche Message-ID: Date: Wed, 15 Jun 2016 10:35:21 +0200 MIME-Version: 1.0 In-Reply-To: <57607D0E.1060907@linux.vnet.ibm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-block@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, axboe@fb.com, tglx@linutronix.de Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+axboe=kernel.dk@lists.infradead.org List-ID: On 06/14/2016 11:54 PM, Guilherme G. Piccoli wrote: > On 06/14/2016 04:58 PM, Christoph Hellwig wrote: > I take this opportunity to ask you something, since I'm working in a > related code in a specific driver - sorry in advance if my question is > silly or if I misunderstood your code. > > The function irq_create_affinity_mask() below deals with the case in > which we have nr_vecs < num_online_cpus(); in this case, wouldn't be a > good idea to trying distribute the vecs among cores? > > Example: if we have 128 online cpus, 8 per core (meaning 16 cores) and > 64 vecs, I guess would be ideal to distribute 4 vecs _per core_, leaving > 4 CPUs in each core without vecs. Hello Christoph and Guilherme, I would also like to see irq_create_affinity_mask() modified such that it implements Guilherme's algorithm. I think blk-mq requests should be processed by a CPU core from the NUMA node from which the request has been submitted. With the proposed algorithm, if the number of MSI-X vectors is less than or equal to the number of CPU cores of a single node, all interrupt vectors will be assigned to the first NUMA node. Bart. _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme