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[156.34.55.100]) by smtp.gmail.com with ESMTPSA id d20sm9874714qto.59.2019.07.17.04.55.08 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 17 Jul 2019 04:55:08 -0700 (PDT) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1hniWZ-0003To-Ns; Wed, 17 Jul 2019 08:55:07 -0300 Date: Wed, 17 Jul 2019 08:55:07 -0300 From: Jason Gunthorpe To: Shamir Rabinovitch Cc: Christoph Hellwig , dledford@redhat.com, leon@kernel.org, monis@mellanox.com, parav@mellanox.com, danielj@mellanox.com, kamalheib1@gmail.com, markz@mellanox.com, swise@opengridcomputing.com, shamir.rabinovitch@oracle.com, johannes.berg@intel.com, willy@infradead.org, michaelgur@mellanox.com, markb@mellanox.com, yuval.shaia@oracle.com, dan.carpenter@oracle.com, bvanassche@acm.org, maxg@mellanox.com, israelr@mellanox.com, galpress@amazon.com, denisd@mellanox.com, yuvalav@mellanox.com, dennis.dalessandro@intel.com, will@kernel.org, ereza@mellanox.com, linux-rdma@vger.kernel.org Subject: Re: [PATCH 00/25] Shared PD and MR Message-ID: <20190717115507.GD12119@ziepe.ca> References: <20190716181200.4239-1-srabinov7@gmail.com> <20190717050931.GA18936@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Wed, Jul 17, 2019 at 02:09:50PM +0300, Shamir Rabinovitch wrote: > On Wed, Jul 17, 2019 at 8:09 AM Christoph Hellwig wrote: > > > > On Tue, Jul 16, 2019 at 09:11:35PM +0300, Shamir Rabinovitch wrote: > > > Following patch-set introduce the shared object feature. > > > > > > A shared object feature allows one process to create HW objects (currently > > > PD and MR) so that a second process can import. > > > > That sounds like a major complication, so you'd better also explain > > the use case very well. > > The main use case was that there is a server that has giant shared > memory that is shared across many processes (lots of mtts). > Each process needs the same memory registration (lots of mrs that > register same memory). > In such scenario, the HCA runs out of mtts. > To solve this problem, an single memory registration is shared across > all the process in that server saving hca mtts. Well, why not just share the entire uverbs FD then? Once the PD is shared all security is lost anyhow.. This is not the model that was explained to me last year Jason