On Tue, May 29, 2018 at 09:22:40AM +0200, Johannes Thumshirn wrote: > On Mon, May 28, 2018 at 11:02:36PM -0400, Mike Snitzer wrote: > > No, what both Red Hat and SUSE are saying is: cool let's have a go at > > "Plan A" but, in parallel, what harm is there in allowing "Plan B" (dm > > multipath) to be conditionally enabled to coexist with native NVMe > > multipath? > > For a "Plan B" we can still use the global knob that's already in > place (even if this reminds me so much about scsi-mq which at least we > haven't turned on in fear of performance regressions).
BTW, for scsi-mq, we have made a little progress by commit 2f31115e940c (scsi: core: introduce force_blk_mq), and virtio-scsi is working at always scsi-mq mode now. Then driver can decide if .force_blk_mq needs to be set. Hope progress can be made in this nvme mpath issue too. Thanks, Ming