Re: [PATCH v3 01/11] PCI/P2PDMA: Support peer-to-peer memory

From: Martin K. Petersen
Date: Thu Mar 15 2018 - 00:01:32 EST



Stephen,

>> It would be useful if those configurations were not left behind so
>> that Linux could feasibly deploy offload code to a controller in the
>> PCI domain.
>
> Agreed. I think this would be great. Kind of like the XCOPY framework
> that was proposed a while back for SCSI devices [1] but updated to also
> include NVMe devices. That is definitely a use case we would like this
> framework to support.

I'm on my umpteenth rewrite of the block/SCSI offload code. It is not as
protocol-agnostic as I would like in the block layer facing downwards.
It has proven quite hard to reconcile token-based and EXTENDED COPY
semantics along with the desire to support stacking. But from an
application/filesystem perspective everything looks the same regardless
of the intricacies of the device. Nothing is preventing us from
supporting other protocols...

--
Martin K. Petersen Oracle Linux Engineering