Re: [RFC PATCH 0/3] kernel: add support for 256-bit IO access

On Thu, Mar 22, 2018 at 5:48 AM, David Laight [off-list ref] wrote:

So if we needed to do PIO reads using the AVX2 (or better AVX-512)
registers would make a significant difference.
Fortunately we can 'dma' most of the data we need to transfer.

I think this is the really fundamental issue.

A device that expects PIO to do some kind of high-performance
transaction is a *broken* device.

It really is that simple. We don't bend over for misdesigned hardware
crap unless it is really common.

I've traced writes before, they are a lot faster and are limited
by things in the fpga fabric (they appear back to back).

The write combine buffer really should be much more effective than any
AVX or similar can ever be.

               Linus