From: Gal Pressman <galpress@amazon.com>
To: "Christian König" <christian.koenig@amd.com>,
"Jason Gunthorpe" <jgg@ziepe.ca>
Cc: Daniel Vetter <daniel@ffwll.ch>,
Sumit Semwal <sumit.semwal@linaro.org>,
Doug Ledford <dledford@redhat.com>,
"open list:DMA BUFFER SHARING FRAMEWORK"
<linux-media@vger.kernel.org>,
dri-devel <dri-devel@lists.freedesktop.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-rdma <linux-rdma@vger.kernel.org>,
Oded Gabbay <ogabbay@habana.ai>, Tomer Tayar <ttayar@habana.ai>,
Yossi Leybovich <sleybo@amazon.com>,
Alexander Matushevsky <matua@amazon.com>,
Leon Romanovsky <leonro@nvidia.com>,
Jianxin Xiong <jianxin.xiong@intel.com>,
John Hubbard <jhubbard@nvidia.com>
Subject: Re: [RFC] Make use of non-dynamic dmabuf in RDMA
Date: Tue, 24 Aug 2021 12:06:00 +0300 [thread overview]
Message-ID: <e2c47256-de89-7eaa-e5c2-5b96efcec834@amazon.com> (raw)
In-Reply-To: <fa124990-ee0c-7401-019e-08109e338042@amd.com>
On 23/08/2021 13:43, Christian König wrote:
> Am 21.08.21 um 11:16 schrieb Gal Pressman:
>> On 20/08/2021 17:32, Jason Gunthorpe wrote:
>>> On Fri, Aug 20, 2021 at 03:58:33PM +0300, Gal Pressman wrote:
>>>
>>>> Though it would've been nicer if we could agree on a solution that could work
>>>> for more than 1-2 RDMA devices, using the existing tools the RDMA subsystem
>>>> has.
>>> I don't think it can really be done, revoke is necessary, and isn't a
>>> primitive we have today.
>>>
>>> Revoke is sort of like rereg MR, but with a guaranteed no-change to
>>> the lkey/rkey
>>>
>>> Then there is the locking complexity of linking the mr creation and
>>> destruction to the lifecycle of the pages, which is messy and maybe
>>> not general. For instance mlx5 would call its revoke_mr, disconnect
>>> the dmabuf then destroy the mkey - but this is only safe because mlx5
>>> HW can handle concurrent revokes.
>> Thanks, that makes sense.
>>
>>>> That's why I tried to approach this by denying such attachments for non-ODP
>>>> importers instead of exposing a "limited" dynamic importer.
>>> That is fine if there is no revoke - once revoke exists we must have
>>> driver and HW support.
>> Agree.
>> IIUC, we're talking about three different exporter "types":
>> - Dynamic with move_notify (requires ODP)
>> - Dynamic with revoke_notify
>> - Static
>>
>> Which changes do we need to make the third one work?
>
> Basically none at all in the framework.
>
> You just need to properly use the dma_buf_pin() function when you start using a
> buffer (e.g. before you create an attachment) and the dma_buf_unpin() function
> after you are done with the DMA-buf.
I replied to your previous mail, but I'll ask again.
Doesn't the pin operation migrate the memory to host memory?
next prev parent reply other threads:[~2021-08-24 9:06 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-18 7:43 [RFC] Make use of non-dynamic dmabuf in RDMA Gal Pressman
2021-08-18 8:00 ` Christian König
2021-08-18 8:37 ` Gal Pressman
2021-08-18 9:34 ` Daniel Vetter
2021-08-19 23:06 ` Jason Gunthorpe
2021-08-20 7:25 ` Daniel Vetter
2021-08-20 12:33 ` Jason Gunthorpe
2021-08-20 12:58 ` Gal Pressman
2021-08-20 14:32 ` Jason Gunthorpe
2021-08-21 9:16 ` Gal Pressman
2021-08-23 10:43 ` Christian König
2021-08-24 9:06 ` Gal Pressman [this message]
2021-08-24 9:32 ` Christian König
2021-08-24 17:27 ` John Hubbard
2021-08-24 17:32 ` Jason Gunthorpe
2021-08-24 17:35 ` John Hubbard
2021-08-24 19:15 ` Dave Airlie
2021-08-24 19:30 ` Jason Gunthorpe
2021-08-24 19:43 ` Alex Deucher
2021-08-24 20:00 ` Xiong, Jianxin
2021-08-25 6:17 ` Christian König
2021-08-25 6:47 ` John Hubbard
2021-08-25 12:18 ` Jason Gunthorpe
2021-08-25 12:27 ` Christian König
2021-08-25 12:38 ` Jason Gunthorpe
2021-08-25 13:51 ` Christian König
2021-08-25 14:47 ` Jason Gunthorpe
2021-08-25 15:14 ` Christian König
2021-08-25 15:49 ` Jason Gunthorpe
2021-08-25 16:02 ` Oded Gabbay
2021-09-01 11:20 ` Gal Pressman
2021-09-01 11:24 ` Christian König
2021-09-02 6:56 ` Gal Pressman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=e2c47256-de89-7eaa-e5c2-5b96efcec834@amazon.com \
--to=galpress@amazon.com \
--cc=christian.koenig@amd.com \
--cc=daniel@ffwll.ch \
--cc=dledford@redhat.com \
--cc=dri-devel@lists.freedesktop.org \
--cc=jgg@ziepe.ca \
--cc=jhubbard@nvidia.com \
--cc=jianxin.xiong@intel.com \
--cc=leonro@nvidia.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-media@vger.kernel.org \
--cc=linux-rdma@vger.kernel.org \
--cc=matua@amazon.com \
--cc=ogabbay@habana.ai \
--cc=sleybo@amazon.com \
--cc=sumit.semwal@linaro.org \
--cc=ttayar@habana.ai \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).