From mboxrd@z Thu Jan 1 00:00:00 1970 From: Doug Ledford Subject: Re: [LSF/MM TOPIC] Discuss least bad options for resolving longterm-GUP usage by RDMA Date: Wed, 06 Feb 2019 21:42:03 -0500 Message-ID: <658363f418a6585a1ffc0038b86c8e95487e8130.camel@redhat.com> References: <20190205175059.GB21617@iweiny-DESK2.sc.intel.com> <20190206095000.GA12006@quack2.suse.cz> <20190206173114.GB12227@ziepe.ca> <20190206175233.GN21860@bombadil.infradead.org> <47820c4d696aee41225854071ec73373a273fd4a.camel@redhat.com> <01000168c43d594c-7979fcf8-b9c1-4bda-b29a-500efe001d66-000000@email.amazonses.com> <20190206210356.GZ6173@dastard> <20190206220828.GJ12227@ziepe.ca> <0c868bc615a60c44d618fb0183fcbe0c418c7c83.camel@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-7DPuKcdbFR8/o52+ZlEI" Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Dan Williams Cc: Jason Gunthorpe , Dave Chinner , Christopher Lameter , Matthew Wilcox , Jan Kara , Ira Weiny , lsf-pc@lists.linux-foundation.org, linux-rdma , Linux MM , Linux Kernel Mailing List , John Hubbard , Jerome Glisse , Michal Hocko List-Id: linux-rdma@vger.kernel.org --=-7DPuKcdbFR8/o52+ZlEI Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2019-02-06 at 14:44 -0800, Dan Williams wrote: > On Wed, Feb 6, 2019 at 2:25 PM Doug Ledford wrote: > > Can someone give me a real world scenario that someone is *actually* > > asking for with this? >=20 > I'll point to this example. At the 6:35 mark Kodi talks about the > Oracle use case for DAX + RDMA. >=20 > https://youtu.be/ywKPPIE8JfQ?t=3D395 I watched this, and I see that Oracle is all sorts of excited that their storage machines can scale out, and they can access the storage and it has basically no CPU load on the storage server while performing millions of queries. What I didn't hear in there is why DAX has to be in the picture, or why Oracle couldn't do the same thing with a simple memory region exported directly to the RDMA subsystem, or why reflink or any of the other features you talk about are needed. So, while these things may legitimately be needed, this video did not tell me about how/why they are needed, just that RDMA is really, *really* cool for their use case and gets them 0% CPU utilization on their storage servers. I didn't watch the whole thing though. Do they get into that later on? Do they get to that level of technical discussion, or is this all higher level? --=20 Doug Ledford GPG KeyID: B826A3330E572FDD Key fingerprint =3D AE6B 1BDA 122B 23B4 265B 1274 B826 A333 0E57 2FDD --=-7DPuKcdbFR8/o52+ZlEI Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEErmsb2hIrI7QmWxJ0uCajMw5XL90FAlxbmvsACgkQuCajMw5X L93hMg/+MsKeTSWBe23u1LbQAPXeHxl4k8Yi91H9RYq8vp1SWYqJCsGxRS8U07tS lYJcnjNYxdIjjUE35E7tTCVS8HzJ9Kyj6DmxGcErb6UAH0QY7QsSTxlS4kzYt4ea FArz31ERKCxfCy7wsryKHdthZ2tpChgZNFqKvklv9GI9hbq5dQB+GdAc6XPOB1K6 reIV0BEUGGuTJbEXLTra+pzikeJZ1yzvOs74qx1PAjvE+gxExRA+CfzndwkKCfgE wgDxfpma8S1bwc9fpke5ea/oQJXsnCBWm6BWpNWZws4/jvAveAWdGECscYiz/6Qu d5gB5hrR689voX0oivLCZ/PpFEngnOmbdruI1ESR4e3kscl+VmSj74CSOyEFv4cN t6A3HgESFXKg2/FR0zVTt1laJdOC3f50U7v946erbuYnLKEwTBKLPZvMRpFz8Wp/ NcVPUJXhgVI0mPDYMUATZ/DJhvPq1SQGhYkBNT524PeVLAh5Uk3NwKljZ8Ubkx3V ISJrWMBSk1G+CHctK6gzh9slamHgjXdw98vJomyxcjdVQFk6LFXk3zWTtOS51YbN EECT/GIgNJRGy8M+jJfO7NbIMh6DKbwBA2SaC3e0Fa2tA3p8KfQ/CgcvdURASvIJ XB51Q2p4hb/n4rr8H1305ZJDHnzEbLVyC4dvwLQ2PjU+OGs0iPk= =xZBH -----END PGP SIGNATURE----- --=-7DPuKcdbFR8/o52+ZlEI--