From: "Stephen Bates" <sbates@raithlin.com>
To: Sagi Grimberg <sagi@grimberg.me>,
Logan Gunthorpe <logang@deltatee.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>
Cc: "Christoph Hellwig" <hch@lst.de>, "Jens Axboe" <axboe@kernel.dk>,
"Keith Busch" <keith.busch@intel.com>,
"Bjorn Helgaas" <bhelgaas@google.com>,
"Jason Gunthorpe" <jgg@mellanox.com>,
"Max Gurtovoy" <maxg@mellanox.com>,
"Dan Williams" <dan.j.williams@intel.com>,
"Jérôme Glisse" <jglisse@redhat.com>,
"Benjamin Herrenschmidt" <benh@kernel.crashing.org>,
"Alex Williamson" <alex.williamson@redhat.com>,
"Steve Wise" <swise@opengridcomputing.com>
Subject: Re: [PATCH v2 10/10] nvmet: Optionally use PCI P2P memory
Date: Thu, 1 Mar 2018 16:15:04 +0000 [thread overview]
Message-ID: <A95AE6BF-1CAC-48F5-B676-DA7BD6D5BF24@raithlin.com> (raw)
In-Reply-To: <749e3752-4349-0bdf-5243-3d510c2b26db@grimberg.me>
> > Ideally, we'd want to use an NVME CMB buffer as p2p memory. This would
> > save an extra PCI transfer as the NVME card could just take the data
> > out of it's own memory. However, at this time, cards with CMB buffers
> > don't seem to be available.
> Can you describe what would be the plan to have it when these devices
> do come along? I'd say that p2p_dev needs to become a nvmet_ns reference
> and not from nvmet_ctrl. Then, when cmb capable devices come along, the
> ns can prefer to use its own cmb instead of locating a p2p_dev device?
Hi Sagi
Thanks for the review! That commit message is somewhat dated as NVMe controllers with CMBs that support RDS and WDS are now commercially available [1]. However we have not yet tried to do any kind of optimization around this yet in terms of determining which p2p_dev to use. Your suggest above looks good and we can look into this kind of optimization in due course.
[1] http://www.eideticom.com/uploads/images/NoLoad_Product_Spec.pdf
>> + ctrl->p2p_dev = pci_p2pmem_find(&ctrl->p2p_clients);
> This is the first p2p_dev found right? What happens if I have more than
> a single p2p device? In theory I'd have more p2p memory I can use. Have
> you considered making pci_p2pmem_find return the least used suitable
> device?
Yes pci_p2pmem_find will always return the first valid p2p_dev found. At the very least we should update this allocate over all the valid p2p_dev. Since the load on any given p2p_dev will vary over time I think a random allocation of the devices makes sense (at least for now).
Stephen
next prev parent reply other threads:[~2018-03-01 16:15 UTC|newest]
Thread overview: 124+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-28 23:39 [PATCH v2 00/10] Copy Offload in NVMe Fabrics with P2P PCI Memory Logan Gunthorpe
2018-02-28 23:39 ` [PATCH v2 01/10] PCI/P2PDMA: Support peer to peer memory Logan Gunthorpe
2018-03-01 17:37 ` Bjorn Helgaas
2018-03-01 18:55 ` Logan Gunthorpe
2018-03-01 23:00 ` Bjorn Helgaas
2018-03-01 23:06 ` Logan Gunthorpe
2018-03-01 23:14 ` Stephen Bates
2018-03-01 23:45 ` Bjorn Helgaas
2018-02-28 23:39 ` [PATCH v2 02/10] PCI/P2PDMA: Add sysfs group to display p2pmem stats Logan Gunthorpe
2018-03-01 17:44 ` Bjorn Helgaas
2018-03-02 0:15 ` Logan Gunthorpe
2018-03-02 0:36 ` Dan Williams
2018-03-02 0:37 ` Logan Gunthorpe
2018-02-28 23:39 ` [PATCH v2 03/10] PCI/P2PDMA: Add PCI p2pmem dma mappings to adjust the bus offset Logan Gunthorpe
2018-03-01 17:49 ` Bjorn Helgaas
2018-03-01 19:36 ` Logan Gunthorpe
2018-02-28 23:40 ` [PATCH v2 04/10] PCI/P2PDMA: Clear ACS P2P flags for all devices behind switches Logan Gunthorpe
2018-03-01 18:02 ` Bjorn Helgaas
2018-03-01 18:54 ` Stephen Bates
2018-03-01 21:21 ` Alex Williamson
2018-03-01 21:26 ` Logan Gunthorpe
2018-03-01 21:32 ` Stephen Bates
2018-03-01 21:35 ` Jerome Glisse
2018-03-01 21:37 ` Logan Gunthorpe
2018-03-01 23:15 ` Bjorn Helgaas
2018-03-01 23:59 ` Logan Gunthorpe
2018-03-01 19:13 ` Logan Gunthorpe
2018-03-05 22:28 ` Bjorn Helgaas
2018-03-05 23:01 ` Logan Gunthorpe
2018-02-28 23:40 ` [PATCH v2 05/10] block: Introduce PCI P2P flags for request and request queue Logan Gunthorpe
2018-03-01 11:08 ` Sagi Grimberg
2018-02-28 23:40 ` [PATCH v2 06/10] IB/core: Add optional PCI P2P flag to rdma_rw_ctx_[init|destroy]() Logan Gunthorpe
2018-03-01 10:32 ` Sagi Grimberg
2018-03-01 17:16 ` Logan Gunthorpe
2018-02-28 23:40 ` [PATCH v2 07/10] nvme-pci: Use PCI p2pmem subsystem to manage the CMB Logan Gunthorpe
2018-03-05 1:33 ` Oliver
2018-03-05 16:00 ` Keith Busch
2018-03-05 17:10 ` Logan Gunthorpe
2018-03-05 18:02 ` Sinan Kaya
2018-03-05 18:09 ` Logan Gunthorpe
2018-03-06 0:49 ` Oliver
2018-03-06 1:14 ` Logan Gunthorpe
2018-03-06 10:40 ` Oliver
2018-03-05 19:57 ` Sagi Grimberg
2018-03-05 20:10 ` Jason Gunthorpe
2018-03-05 20:16 ` Logan Gunthorpe
2018-03-05 20:42 ` Keith Busch
2018-03-05 20:50 ` Jason Gunthorpe
2018-03-05 20:13 ` Logan Gunthorpe
2018-02-28 23:40 ` [PATCH v2 08/10] nvme-pci: Add support for P2P memory in requests Logan Gunthorpe
2018-03-01 11:07 ` Sagi Grimberg
2018-03-01 15:58 ` Stephen Bates
2018-03-09 5:08 ` Bart Van Assche
2018-02-28 23:40 ` [PATCH v2 09/10] nvme-pci: Add a quirk for a pseudo CMB Logan Gunthorpe
2018-03-01 11:03 ` Sagi Grimberg
2018-02-28 23:40 ` [PATCH v2 10/10] nvmet: Optionally use PCI P2P memory Logan Gunthorpe
2018-03-01 11:03 ` Sagi Grimberg
2018-03-01 16:15 ` Stephen Bates [this message]
2018-03-01 17:40 ` Logan Gunthorpe
2018-03-01 18:35 ` Sagi Grimberg
2018-03-01 18:42 ` Jason Gunthorpe
2018-03-01 19:01 ` Stephen Bates
2018-03-01 19:27 ` Logan Gunthorpe
2018-03-01 22:45 ` Jason Gunthorpe
2018-03-01 22:56 ` Logan Gunthorpe
2018-03-01 23:00 ` Stephen Bates
2018-03-01 23:20 ` Jason Gunthorpe
2018-03-01 23:29 ` Logan Gunthorpe
2018-03-01 23:32 ` Stephen Bates
2018-03-01 23:49 ` Keith Busch
2018-03-01 23:52 ` Logan Gunthorpe
2018-03-01 23:53 ` Stephen Bates
2018-03-02 15:53 ` Christoph Hellwig
2018-03-02 20:51 ` Stephen Bates
2018-03-01 23:57 ` Stephen Bates
2018-03-02 0:03 ` Logan Gunthorpe
2018-03-02 16:18 ` Jason Gunthorpe
2018-03-02 17:10 ` Logan Gunthorpe
2018-03-01 19:10 ` Logan Gunthorpe
2018-03-01 3:54 ` [PATCH v2 00/10] Copy Offload in NVMe Fabrics with P2P PCI Memory Benjamin Herrenschmidt
2018-03-01 3:56 ` Benjamin Herrenschmidt
2018-03-01 18:04 ` Logan Gunthorpe
2018-03-01 20:29 ` Benjamin Herrenschmidt
2018-03-01 20:55 ` Jerome Glisse
2018-03-01 21:03 ` Logan Gunthorpe
2018-03-01 21:10 ` Jerome Glisse
2018-03-01 21:15 ` Logan Gunthorpe
2018-03-01 21:25 ` Jerome Glisse
2018-03-01 21:37 ` Stephen Bates
2018-03-02 21:38 ` Stephen Bates
2018-03-02 22:09 ` Jerome Glisse
2018-03-05 20:36 ` Stephen Bates
2018-03-01 20:55 ` Logan Gunthorpe
2018-03-01 18:09 ` Stephen Bates
2018-03-01 20:32 ` Benjamin Herrenschmidt
2018-03-01 19:21 ` Dan Williams
2018-03-01 19:30 ` Logan Gunthorpe
2018-03-01 20:34 ` Benjamin Herrenschmidt
2018-03-01 20:40 ` Benjamin Herrenschmidt
2018-03-01 20:53 ` Jason Gunthorpe
2018-03-01 20:57 ` Logan Gunthorpe
2018-03-01 22:06 ` Benjamin Herrenschmidt
2018-03-01 22:31 ` Linus Torvalds
2018-03-01 22:34 ` Benjamin Herrenschmidt
2018-03-02 16:22 ` Kani, Toshi
2018-03-02 16:57 ` Linus Torvalds
2018-03-02 17:34 ` Linus Torvalds
2018-03-02 17:38 ` Kani, Toshi
2018-03-01 21:37 ` Dan Williams
2018-03-01 21:45 ` Logan Gunthorpe
2018-03-01 21:57 ` Logan Gunthorpe
2018-03-01 23:00 ` Benjamin Herrenschmidt
2018-03-01 23:19 ` Logan Gunthorpe
2018-03-01 23:25 ` Benjamin Herrenschmidt
2018-03-02 21:44 ` Benjamin Herrenschmidt
2018-03-02 22:24 ` Logan Gunthorpe
2018-03-01 23:26 ` Benjamin Herrenschmidt
2018-03-01 23:54 ` Logan Gunthorpe
2018-03-01 21:03 ` Benjamin Herrenschmidt
2018-03-01 21:11 ` Logan Gunthorpe
2018-03-01 21:18 ` Jerome Glisse
2018-03-01 21:22 ` Logan Gunthorpe
2018-03-01 10:31 ` Sagi Grimberg
2018-03-01 19:33 ` Logan Gunthorpe
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