Support for registering buffers which use file backed memory?

[MA-ETL]

As I understand, currently io_uring_register() does not currently support registering buffers which use file backed memory. I was wondering, has there been any attempt to enable this functionality and what would be needed in order to make this work?

[axboe]

It has some potentially nasty side effects with writeback, which is why it isn't currently allowed.

But I'm curious, what's the motivation for pursuing file backed memory for buffers?

[axboe]

Oh, fwiw, should work with file backed huge pages...

[ollie-etl]

But I'm curious, what's the motivation for pursuing file backed memory for buffers?

Working with mmap'd driver allocated memory

[isilence]

But I'm curious, what's the motivation for pursuing file backed memory for buffers?

Working with mmap'd driver allocated memory

We allow some file backed mappings, but they're rather white listed one by one. What driver / type of memory you're specifically interested in?

[ollie-etl]

The driver is to a peripheral which produces streams of data via a DMA. The memory is normal DDR4, but is device memory, and the penalty for using system memory is huge (large bandwidth bottleneck).
This is a Xilinx MPSoC device, to give you an idea of what system is being used / NUMA domains.