Re: [PATCH v2 10/10] nvmet: Optionally use PCI P2P memory

[Stephen Bates]

>> We'd prefer to have a generic way to get p2pmem instead of restricting
>> ourselves to only using CMBs. We did work in the past where the P2P memory
 >> was part of an IB adapter and not the NVMe card. So this won't work if it's
  >> an NVMe only interface.
    
 > It just seems like it it making it too complicated.

I disagree. Having a common allocator (instead of some separate allocator per driver) makes things simpler.

> Seems like a very subtle and hard to debug performance trap to leave
> for the users, and pretty much the only reason to use P2P is
> performance... So why have such a dangerous interface?

P2P is about offloading the memory and PCI subsystem of the host CPU and this is achieved no matter which p2p_dev is used.

Stephen