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SubjectRe: [RFC PATCH 2/3] x86/io: implement 256-bit IO read and write
On Tuesday, March 03/20/18, 2018 at 20:10:19 +0530, David Laight wrote:
> 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.
>

Unfortunately, our device doesn't support doing DMA of on-chip 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().)
>

We also need to collect this in kernel space i.e. from crash recovery
kernel.

Thanks,
Rahul

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