RE: [RFC PATCH 2/3] x86/io: implement 256-bit IO read and write

From: David Laight
Date: Tue Mar 20 2018 - 10:39:41 EST


From: Rahul Lakkireddy
> Sent: 20 March 2018 13:32
...
> On High Availability Server, the logs of the failing system must be
> collected as quickly as possible. So, we're concerned with the amount
> of time taken to collect our large on-chip memory. We see improvement
> in doing 256-bit reads at a time.

Two other options:

1) Get the device to DMA into host memory.

2) Use mmap() (and vm_iomap_memory() in your driver) to get direct
userspace access to the (I assume) PCIe memory space.
You can then use whatever copy instructions the cpu has.
(Just don't use memcpy().)

David