From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 1 Mar 2018 16:49:30 -0700 From: Keith Busch To: Stephen Bates Cc: Jason Gunthorpe , Logan Gunthorpe , Sagi Grimberg , "linux-kernel@vger.kernel.org" , "linux-pci@vger.kernel.org" , "linux-nvme@lists.infradead.org" , "linux-rdma@vger.kernel.org" , "linux-nvdimm@lists.01.org" , "linux-block@vger.kernel.org" , Christoph Hellwig , Jens Axboe , Bjorn Helgaas , Max Gurtovoy , Dan Williams , =?iso-8859-1?B?Suly9G1l?= Glisse , Benjamin Herrenschmidt , Alex Williamson , Steve Wise Subject: Re: [PATCH v2 10/10] nvmet: Optionally use PCI P2P memory Message-ID: <20180301234930.GG14799@localhost.localdomain> References: <20180228234006.21093-1-logang@deltatee.com> <20180228234006.21093-11-logang@deltatee.com> <749e3752-4349-0bdf-5243-3d510c2b26db@grimberg.me> <40d69074-31a8-d06a-ade9-90de7712c553@deltatee.com> <5649098f-b775-815b-8b9a-f34628873ff4@grimberg.me> <20180301184249.GI19007@ziepe.ca> <20180301224540.GL19007@ziepe.ca> <77591162-4CCD-446E-A27C-1CDB4996ACB7@raithlin.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <77591162-4CCD-446E-A27C-1CDB4996ACB7@raithlin.com> List-ID: On Thu, Mar 01, 2018 at 11:00:51PM +0000, Stephen Bates wrote: > > P2P is about offloading the memory and PCI subsystem of the host CPU > and this is achieved no matter which p2p_dev is used. Even within a device, memory attributes for its various regions may not be the same. There's a meaningful difference between writing to an NVMe CMB vs PMR, and a single device could have both. We don't want to lump these all together without knowing which region you're allocating from, right?