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From: Logan Gunthorpe <logang-OTvnGxWRz7hWk0Htik3J/w@public.gmane.org>
To: Jason Gunthorpe <jgg-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Cc: Joerg Roedel <jroedel-l3A5Bk7waGM@public.gmane.org>,
	"Rafael J . Wysocki"
	<rafael-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Greg Kroah-Hartman
	<gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>,
	Felix Kuehling <Felix.Kuehling-5C7GfCeVMHo@public.gmane.org>,
	"linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
	<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	"dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org"
	<dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org>,
	Christian Koenig <christian.koenig-5C7GfCeVMHo@public.gmane.org>,
	"linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org"
	<linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org>,
	Jerome Glisse <jglisse-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	"iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org"
	<iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>,
	"linux-pci-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
	<linux-pci-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	Bjorn Helgaas <bhelgaas-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>,
	Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
Subject: Re: [RFC PATCH 3/5] mm/vma: add support for peer to peer to device vma
Date: Wed, 30 Jan 2019 12:48:33 -0700	[thread overview]
Message-ID: <3793c115-2451-1479-29a9-04bed2831e4b@deltatee.com> (raw)
In-Reply-To: <20190130191946.GD17080-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>



On 2019-01-30 12:19 p.m., Jason Gunthorpe wrote:
> On Wed, Jan 30, 2019 at 11:13:11AM -0700, Logan Gunthorpe wrote:
>>
>>
>> On 2019-01-30 10:44 a.m., Jason Gunthorpe wrote:
>>> I don't see why a special case with a VMA is really that different.
>>
>> Well one *really* big difference is the VMA changes necessarily expose
>> specialized new functionality to userspace which has to be supported
>> forever and may be difficult to change. 
> 
> The only user change here is that more things will succeed when
> creating RDMA MRs (and vice versa to GPU). I don't think this
> restricts the kernel implementation at all, unless we intend to
> remove P2P entirely..

Well for MRs I'd expect you are using struct pages to track the memory
some how.... VMAs that aren't backed by pages and use this special
interface must therefore be creating new special interfaces that can
call p2p_[un]map...

I'd much rather see special cases around struct page so we can find ways
to generalize it in the future than create special cases tied to random
userspace interfaces.

Logan

  parent reply	other threads:[~2019-01-30 19:48 UTC|newest]

Thread overview: 95+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-29 17:47 [RFC PATCH 0/5] Device peer to peer (p2p) through vma jglisse
2019-01-29 17:47 ` [RFC PATCH 1/5] pci/p2p: add a function to test peer to peer capability jglisse
2019-01-29 18:24   ` Logan Gunthorpe
2019-01-29 19:44     ` Greg Kroah-Hartman
2019-01-29 19:53       ` Jerome Glisse
2019-01-29 20:44       ` Logan Gunthorpe
2019-01-29 21:00         ` Jerome Glisse
2019-01-29 19:56   ` Alex Deucher
2019-01-29 20:00     ` Jerome Glisse
2019-01-29 20:24     ` Logan Gunthorpe
2019-01-29 21:28       ` Alex Deucher
2019-01-30 10:25       ` Christian König
2019-01-29 17:47 ` [RFC PATCH 2/5] drivers/base: " jglisse
2019-01-29 18:26   ` Logan Gunthorpe
2019-01-29 19:54     ` Jerome Glisse
2019-01-29 19:46   ` Greg Kroah-Hartman
2019-01-29 19:56     ` Jerome Glisse
2019-01-29 17:47 ` [RFC PATCH 3/5] mm/vma: add support for peer to peer to device vma jglisse
2019-01-29 18:36   ` Logan Gunthorpe
2019-01-29 19:11     ` Jerome Glisse
2019-01-29 19:24       ` Logan Gunthorpe
2019-01-29 19:44         ` Jerome Glisse
2019-01-29 20:43           ` Logan Gunthorpe
2019-01-30  7:52             ` Christoph Hellwig
2019-01-29 19:32       ` Jason Gunthorpe
2019-01-29 19:50         ` Jerome Glisse
2019-01-29 20:24           ` Jason Gunthorpe
2019-01-29 20:44             ` Jerome Glisse
2019-01-29 23:02               ` Jason Gunthorpe
2019-01-30  0:08                 ` Jerome Glisse
2019-01-30  4:30                   ` Jason Gunthorpe
2019-01-30 15:43                     ` Jerome Glisse
2019-01-29 20:39         ` Logan Gunthorpe
2019-01-29 20:57           ` Jerome Glisse
2019-01-29 21:30             ` Logan Gunthorpe
2019-01-29 21:50               ` Jerome Glisse
2019-01-29 22:58                 ` Logan Gunthorpe
2019-01-29 23:47                   ` Jerome Glisse
2019-01-30  1:17                     ` Logan Gunthorpe
2019-01-30  2:48                       ` Jerome Glisse
2019-01-30  4:18                       ` Jason Gunthorpe
2019-01-30  8:00                         ` Christoph Hellwig
2019-01-30 15:49                           ` Jerome Glisse
2019-01-30 19:06                           ` Jason Gunthorpe
     [not found]                             ` <20190130190651.GC17080-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
2019-01-30 19:45                               ` Logan Gunthorpe
     [not found]                                 ` <840256f8-0714-5d7d-e5f5-c96aec5c2c05-OTvnGxWRz7hWk0Htik3J/w@public.gmane.org>
2019-01-30 19:59                                   ` Jason Gunthorpe
     [not found]                                     ` <20190130195900.GG17080-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
2019-01-30 21:01                                       ` Logan Gunthorpe
     [not found]                                         ` <35bad6d5-c06b-f2a3-08e6-2ed0197c8691-OTvnGxWRz7hWk0Htik3J/w@public.gmane.org>
2019-01-30 21:50                                           ` Jason Gunthorpe
     [not found]                                             ` <20190130215019.GL17080-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
2019-01-30 22:52                                               ` Logan Gunthorpe
2019-01-30 23:30                                                 ` Jason Gunthorpe
2019-01-31  8:13                                                 ` Christoph Hellwig
2019-01-31 15:37                                                   ` Jerome Glisse
2019-01-31 19:02                                                   ` Jason Gunthorpe
2019-01-31 19:19                                                     ` Logan Gunthorpe
2019-01-31 19:54                                                       ` Jason Gunthorpe
2019-01-31 19:35                                                     ` Jerome Glisse
2019-01-31 19:44                                                       ` Logan Gunthorpe
2019-01-31 19:58                                                       ` Jason Gunthorpe
2019-01-30 17:17                         ` Logan Gunthorpe
     [not found]                           ` <bdf03cd5-f5b1-4b78-a40e-b24024ca8c9f-OTvnGxWRz7hWk0Htik3J/w@public.gmane.org>
2019-01-30 18:56                             ` Jason Gunthorpe
     [not found]                               ` <20190130185652.GB17080-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
2019-01-30 19:22                                 ` Jerome Glisse
2019-01-30 19:38                                   ` Jason Gunthorpe
     [not found]                                     ` <20190130193759.GE17080-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
2019-01-30 20:00                                       ` Logan Gunthorpe
2019-01-30 20:11                                         ` Jason Gunthorpe
2019-01-30 20:43                                           ` Jerome Glisse
     [not found]                                             ` <20190130204332.GF5061-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2019-01-30 20:50                                               ` Jason Gunthorpe
2019-01-30 21:45                                                 ` Jerome Glisse
     [not found]                                                   ` <20190130214525.GG5061-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2019-01-30 21:56                                                     ` Jason Gunthorpe
2019-01-30 22:30                                                       ` Jerome Glisse
     [not found]                                                         ` <20190130223027.GH5061-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2019-01-30 22:33                                                           ` Jason Gunthorpe
2019-01-30 22:47                                                             ` Jerome Glisse
     [not found]                                                               ` <20190130224705.GI5061-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2019-01-30 22:51                                                                 ` Jason Gunthorpe
2019-01-30 22:58                                                                   ` Jerome Glisse
     [not found]                                   ` <20190130192234.GD5061-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2019-01-30 19:52                                     ` Logan Gunthorpe
2019-01-30 20:35                                       ` Jerome Glisse
2019-01-29 20:58           ` Jason Gunthorpe
2019-01-30  8:02             ` Christoph Hellwig
2019-01-30 10:33               ` Koenig, Christian
2019-01-30 15:55                 ` Jerome Glisse
2019-01-30 17:26                   ` Christoph Hellwig
2019-01-30 17:32                     ` Logan Gunthorpe
2019-01-30 17:39                     ` Jason Gunthorpe
2019-01-30 18:05                     ` Jerome Glisse
2019-01-30 17:44               ` Jason Gunthorpe
2019-01-30 18:13                 ` Logan Gunthorpe
2019-01-30 18:50                   ` Jerome Glisse
2019-01-31  8:02                     ` Christoph Hellwig
2019-01-31 15:03                       ` Jerome Glisse
2019-01-30 19:19                   ` Jason Gunthorpe
     [not found]                     ` <20190130191946.GD17080-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
2019-01-30 19:48                       ` Logan Gunthorpe [this message]
2019-01-30 20:44                         ` Jason Gunthorpe
2019-01-31  8:05                           ` Christoph Hellwig
2019-01-31 15:11                             ` Jerome Glisse
2019-01-29 17:47 ` [RFC PATCH 4/5] mm/hmm: add support for peer to peer to HMM device memory jglisse
2019-01-29 17:47 ` [RFC PATCH 5/5] mm/hmm: add support for peer to peer to special device vma jglisse

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