On Tue, Dec 22 2020 at 8:32am -0500, Christoph Hellwig hch@infradead.org wrote:
On Mon, Dec 14, 2020 at 07:00:57PM -0800, Palmer Dabbelt wrote:
I haven't gotten a whole lot of feedback, so I'm inclined to at least have some reasonable performance numbers before bothering with a v2.
FYI, my other main worry beside duplicating nbd is that device mapper really is a stacked interface that sits on top of other block device. Turning this into something else that just pipes data to userspace seems very strange.
I agree. Only way I'd be interested is if it somehow tackled enabling much more efficient IO. Earlier discussion in this thread mentioned that zero-copy and low overhead wasn't a priority (because it is hard, etc). But the hard work has already been done with io_uring. If dm-user had a prereq of leaning heavily on io_uring and also enabled IO polling for bio-based then there may be a win to supporting it.
But unless lower latency (or some other more significant win) is made possible I just don't care to prop up an unnatural DM bolt-on.
Mike