From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) (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 9802021F833CA for ; Fri, 5 Jan 2018 10:53:18 -0800 (PST) Date: Fri, 5 Jan 2018 12:01:35 -0700 From: Keith Busch Subject: Re: [PATCH 09/12] nvme-pci: Use PCI p2pmem subsystem to manage the CMB Message-ID: <20180105190135.GB10657@localhost.localdomain> References: <20180104190137.7654-1-logang@deltatee.com> <20180104190137.7654-10-logang@deltatee.com> <20180105181152.GA10657@localhost.localdomain> <6c89e4b4-1854-c251-a5ec-7e54bc8085fc@deltatee.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <6c89e4b4-1854-c251-a5ec-7e54bc8085fc@deltatee.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Logan Gunthorpe Cc: Jens Axboe , linux-nvdimm@lists.01.org, linux-rdma@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, =?iso-8859-1?B?Suly9G1l?= Glisse , Jason Gunthorpe , Benjamin Herrenschmidt , Bjorn Helgaas , Max Gurtovoy , Christoph Hellwig List-ID: On Fri, Jan 05, 2018 at 11:19:28AM -0700, Logan Gunthorpe wrote: > Although it is not explicitly stated anywhere, pci_alloc_p2pmem() should > always be at least 4k aligned. This is because the gen_pool that implements > it is created with PAGE_SHIFT for its min_alloc_order. Ah, I see that now. Thanks for the explanation. Does it need to be created with page sized minimum alloc order? That granularity makes it difficult to fit SQs in CMB on archs with larger pages when we only needed 4k alignment. I was also hoping to extend this for PRP/SGL in CMB where even 4k is too high a granularity to make it really useful. It looks like creating the gen pool with a smaller minimum and gen_pool_first_fit_order_align algo would satisfy my use cases, but I'm not sure if there's another reason you've set it to page alignment. _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm