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Date: Tue, 7 May 2024 14:56:44 -0300
From: Jason Gunthorpe <jgg@ziepe.ca>
To: Pavel Begunkov <asml.silence@gmail.com>
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Subject: Re: [RFC PATCH net-next v8 02/14] net: page_pool: create hooks for
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On Tue, May 07, 2024 at 06:25:52PM +0100, Pavel Begunkov wrote:
> On 5/7/24 17:48, Jason Gunthorpe wrote:
> > On Tue, May 07, 2024 at 09:42:05AM -0700, Mina Almasry wrote:
> > 
> > > 1. Align with devmem TCP to use udmabuf for your io_uring memory. I
> > > think in the past you said it's a uapi you don't link but in the face
> > > of this pushback you may want to reconsider.
> > 
> > dmabuf does not force a uapi, you can acquire your pages however you
> > want and wrap them up in a dmabuf. No uapi at all.
> > 
> > The point is that dmabuf already provides ops that do basically what
> > is needed here. We don't need ops calling ops just because dmabuf's
> > ops are not understsood or not perfect. Fixup dmabuf.
> 
> Those ops, for example, are used to efficiently return used buffers
> back to the kernel, which is uapi, I don't see how dmabuf can be
> fixed up to cover it.

Sure, but that doesn't mean you can't use dma buf for the other parts
of the flow. The per-page lifetime is a different topic than the
refcounting and access of the entire bulk of memory.

Jason