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Groups > linux.kernel > #1536353

Re: Enabling peer to peer device transactions for PCIe devices

From Logan Gunthorpe <logang@deltatee.com>
Newsgroups linux.kernel
Subject Re: Enabling peer to peer device transactions for PCIe devices
Date 2016-12-05 20:30 +0100
Message-ID <sL77A-bb-7@gated-at.bofh.it> (permalink)
References (6 earlier) <sL5Sa-7U6-7@gated-at.bofh.it> <sL5Sa-7U6-5@gated-at.bofh.it> <sL6lc-87B-29@gated-at.bofh.it> <sL6uR-8aT-1@gated-at.bofh.it> <sL6XT-81-15@gated-at.bofh.it>
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On 05/12/16 12:14 PM, Jason Gunthorpe wrote:
> But CMB sounds much more like the GPU case where there is a
> specialized allocator handing out the BAR to consumers, so I'm not
> sure a general purpose chardev makes a lot of sense?

I don't think it will ever need to be as complicated as the GPU case. 
There will probably only ever be a relatively small amount of memory 
behind the CMB and really the only users are those doing P2P work. Thus 
the specialized allocator could be pretty simple and I expect it would 
be fine to just return -ENOMEM if there is not enough memory.

Also, if it was implemented this way, if there was a need to make the 
allocator more complicated it could easily be added later as the 
userspace interface is just mmap to obtain a buffer.

Logan

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Thread

Re: Enabling peer to peer device transactions for PCIe devices Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-11-25 20:40 +0100
  Re: Enabling peer to peer device transactions for PCIe devices Christian König <deathsimple@vodafone.de> - 2016-11-25 21:50 +0100
    Re: Enabling peer to peer device transactions for PCIe devices Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-11-25 22:20 +0100
  Re: Enabling peer to peer device transactions for PCIe devices Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-11-28 18:00 +0100
    Re: Enabling peer to peer device transactions for PCIe devices Logan Gunthorpe <logang@deltatee.com> - 2016-11-28 19:30 +0100
      Re: Enabling peer to peer device transactions for PCIe devices Logan Gunthorpe <logang@deltatee.com> - 2016-11-28 22:40 +0100
        Re: Enabling peer to peer device transactions for PCIe devices Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-11-28 23:30 +0100
    Re: Enabling peer to peer device transactions for PCIe devices Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-11-28 20:10 +0100
      Re: Enabling peer to peer device transactions for PCIe devices Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-11-30 17:30 +0100
        Re: Enabling peer to peer device transactions for PCIe devices Logan Gunthorpe <logang@deltatee.com> - 2016-11-30 19:10 +0100
          Re: Enabling peer to peer device transactions for PCIe devices "Stephen Bates" <sbates@raithlin.com> - 2016-12-04 14:10 +0100
          Re: Enabling peer to peer device transactions for PCIe devices "Stephen Bates" <sbates@raithlin.com> - 2016-12-04 14:50 +0100
            Re: Enabling peer to peer device transactions for PCIe devices Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-12-05 18:20 +0100
              Re: Enabling peer to peer device transactions for PCIe devices Dan Williams <dan.j.williams@intel.com> - 2016-12-05 18:50 +0100
                Re: Enabling peer to peer device transactions for PCIe devices Dan Williams <dan.j.williams@intel.com> - 2016-12-05 19:10 +0100
                Re: Enabling peer to peer device transactions for PCIe devices Logan Gunthorpe <logang@deltatee.com> - 2016-12-05 19:40 +0100
                Re: Enabling peer to peer device transactions for PCIe devices Dan Williams <dan.j.williams@intel.com> - 2016-12-05 19:50 +0100
                Re: Enabling peer to peer device transactions for PCIe devices Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-12-05 20:20 +0100
                Re: Enabling peer to peer device transactions for PCIe devices Logan Gunthorpe <logang@deltatee.com> - 2016-12-05 20:30 +0100
                Re: Enabling peer to peer device transactions for PCIe devices Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-12-05 20:50 +0100
                Re: Enabling peer to peer device transactions for PCIe devices Logan Gunthorpe <logang@deltatee.com> - 2016-12-05 21:00 +0100
                Re: Enabling peer to peer device transactions for PCIe devices Christoph Hellwig <hch@infradead.org> - 2016-12-05 21:10 +0100
                Re: Enabling peer to peer device transactions for PCIe devices "Stephen Bates" <sbates@raithlin.com> - 2016-12-06 09:30 +0100
                Re: Enabling peer to peer device transactions for PCIe devices Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-12-06 17:40 +0100
                Re: Enabling peer to peer device transactions for PCIe devices Logan Gunthorpe <logang@deltatee.com> - 2016-12-06 18:00 +0100
                Re: Enabling peer to peer device transactions for PCIe devices Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-12-06 18:30 +0100
                Re: Enabling peer to peer device transactions for PCIe devices Logan Gunthorpe <logang@deltatee.com> - 2016-12-06 22:50 +0100
                Re: Enabling peer to peer device transactions for PCIe devices Dan Williams <dan.j.williams@intel.com> - 2016-12-06 23:10 +0100
                Re: Enabling peer to peer device transactions for PCIe devices Christoph Hellwig <hch@infradead.org> - 2016-12-06 18:20 +0100
                Re: Enabling peer to peer device transactions for PCIe devices Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-12-05 19:10 +0100
      RE: Enabling peer to peer device transactions for PCIe devices "Deucher, Alexander" <Alexander.Deucher@amd.com> - 2016-11-30 18:50 +0100
    Re: Enabling peer to peer device transactions for PCIe devices Haggai Eran <haggaie@mellanox.com> - 2016-11-28 21:00 +0100
  Re: Enabling peer to peer device transactions for PCIe devices Haggai Eran <haggaie@mellanox.com> - 2016-11-28 19:40 +0100

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