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From: "Stephen  Bates" <sbates@raithlin.com>
To: Jerome Glisse <jglisse@redhat.com>,
	Logan Gunthorpe <logang@deltatee.com>
Cc: Benjamin Herrenschmidt <benh@au1.ibm.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>,
	Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
	Keith Busch <keith.busch@intel.com>,
	Sagi Grimberg <sagi@grimberg.me>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Jason Gunthorpe <jgg@mellanox.com>,
	Max Gurtovoy <maxg@mellanox.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Oliver OHalloran <oliveroh@au1.ibm.com>
Subject: Re: [PATCH v2 00/10] Copy Offload in NVMe Fabrics with P2P PCI Memory
Date: Fri, 2 Mar 2018 21:38:43 +0000	[thread overview]
Message-ID: <8D3B5C26-39E0-478D-B51F-A22B3F36C4D7@raithlin.com> (raw)
In-Reply-To: <20180301211036.GB6742@redhat.com>

> It seems people miss-understand HMM :( 

Hi Jerome

Your unhappy face emoticon made me sad so I went off to (re)read up on HMM. Along the way I came up with a couple of things.

While hmm.txt is really nice to read it makes no mention of DEVICE_PRIVATE and DEVICE_PUBLIC. It also gives no indication when one might choose to use one over the other. Would it be possible to update hmm.txt to include some discussion on this? I understand that DEVICE_PUBLIC creates a mapping in the kernel's linear address space for the device memory and DEVICE_PRIVATE does not. However, like I said, I am not sure when you would use either one and the pros and cons of doing so. I actually ended up finding some useful information in memremap.h but I don't think it is fair to expect people to dig *that* deep to find this information ;-).

A quick grep shows no drivers using the HMM API in the upstream code today. Is this correct? Are there any examples of out of tree drivers that use HMM you can point me too? As a driver developer what resources exist to help me write a HMM aware driver?

The (very nice) hmm.txt document is not references in the MAINTAINERS file? You might want to fix that when you have a moment.

Stephen

  parent reply	other threads:[~2018-03-02 21:38 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
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 [this message]
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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