> From: Andrew Cooper [mailto:andrew.coop...@citrix.com] > Sent: Tuesday, February 02, 2016 2:25 AM > > On 01/02/16 05:44, Haozhong Zhang wrote: > > Hi, > > > > The following document describes the design of adding vNVDIMM support > > for Xen. Any comments are welcome. > > > > Thanks, > > Haozhong > > Thankyou for doing this. It is a very comprehensive document, and a > fantastic example for future similar situations.
Agree. It's a very good doc to help following discussions. > > > To start with however, I would like to clear up my confusion over the > the usecases of pmem vs pblk. > > pblk, using indirect access, is less efficient than pmem. NVDIMMs > themselves are slower (and presumably more expensive) than equivalent > RAM, and presumably still has a finite number of write cycles, so I > don't buy an argument suggesting that they are a plausible replacement > for real RAM. for pblk, I think it's more meaningful to compare with today's SSD. > > I presume therefore that a system would only choose to use pblk mode in > situations where the host physical address space is a limiting factor. > Are there other situations which I have overlooked? I think you more mean RAM size limitation here. Today 48bit physical address space is not limiting yet. :-) > > Secondly, I presume that pmem vs pblk will be a firmware decision and > fixed from the point of view of the Operating System? > Yes from the description of ACPI manner. Thanks Kevin _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
