Re: RFC Block Layer Extensions to Support NV-DIMMs

From: Matthew Wilcox
Date: Thu Sep 26 2013 - 13:56:36 EST

On Thu, Sep 26, 2013 at 02:56:17PM +0000, Zuckerman, Boris wrote:
> To work with persistent memory as efficiently as we can work with RAM we need a bit more than "commit". It's reasonable to expect that we get some additional support from CPUs that goes beyond mfence and mflush. That may include discovery, transactional support, etc. Encapsulating that in a special class sooner than later seams a right thing to do...

If it's something CPU-specific, then we wouldn't handle it as part of
the "class", we'd handle it as an architecture abstraction. It's only
operations which are device-specific which would need to be exposed
through an operations vector. For example, suppose you buy one device
from IBM and another device from HP, and plug them both into your SPARC
system. The code you compile needs to run on SPARC, doing whatever
CPU operations are supported, but if HP and IBM have different ways of
handling a "commit" operation, we need that operation to be part of an
operations vector.
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