Am 22.06.21 um 01:29 schrieb Jason Gunthorpe:

On Mon, Jun 21, 2021 at 10:24:16PM +0300, Oded Gabbay wrote:

quoted

Another thing I want to emphasize is that we are doing p2p only
through the export/import of the FD. We do *not* allow the user to
mmap the dma-buf as we do not support direct IO. So there is no access
to these pages through the userspace.

Arguably mmaping the memory is a better choice, and is the direction
that Logan's series goes in. Here the use of DMABUF was specifically
designed to allow hitless revokation of the memory, which this isn't
even using.

The major problem with this approach is that DMA-buf is also used for 
memory which isn't CPU accessible.

That was one of the reasons we didn't even considered using the mapping 
memory approach for GPUs.

Regards,
Christian.

So you are taking the hit of very limited hardware support and reduced
performance just to squeeze into DMABUF..

Jason
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