On Wed, Oct 21, 2020 at 7:24 AM Mike Snitzer [off-list ref] wrote:

Hey Dan,

On Fri, Oct 16, 2020 at 6:38 PM Dan Williams [off-list ref] wrote:

quoted

On Fri, Oct 16, 2020 at 2:59 PM Nabeel Meeramohideen Mohamed
(nmeeramohide) [off-list ref] wrote:

quoted

(5) Representing an mpool as a /dev/mpool/<mpool-name> device file provides a
convenient mechanism for controlling access to and managing the multiple storage
volumes, and in the future pmem devices, that may comprise an logical mpool.

Christoph and I have talked about replacing the pmem driver's
dependence on device-mapper for pooling.

Was this discussion done publicly or private?  If public please share
a pointer to the thread.

I'd really like to understand the problem statement that is leading to
pursuing a pmem native alternative to existing DM.

IIRC it was during the hallway track at a conference. Some of the
concern is the flexibility to carve physical address space but not
attach a block-device in front of it, and allow pmem/dax-capable
filesystems to mount on something other than a block-device.

DM does fit the bill for block-device concatenation and striping, but
there's some pressure to have a level of provisioning beneath that.

The device-dax facility has already started to grow some physical
address space partitioning capabilities this cycle, see 60e93dc097f7
device-dax: add dis-contiguous resource support, and the question
becomes when / if that support needs to extend across regions is DM
the right tool for that?