dm-multipath low performance with blk-mq

[Mike Snitzer]

On Tue, Jan 26 2016 at 11:44am -0500,
Christoph Hellwig <hch at infradead.org> wrote:

> On Tue, Jan 26, 2016 at 11:03:24AM -0500, Mike Snitzer wrote:
> > Christoph, any chance you could rebase your 'nvme-loop.2' on v4.5-rc1?
> 
> Don't think I have time at the moment, sorry..

No problem, I pulled the latest DM changes ontop of 'nvme-loop.2', see:
http://git.kernel.org/cgit/linux/kernel/git/snitzer/linux.git/log/?h=devel

I was able to use nvme-loop like was documented here:
http://git.infradead.org/users/hch/block.git/commit/47d8d5b1db270463b5bd7b6a68cd89bd8762840d

But I'm not too sure how Sagi used the resulting nvme device with
multipath.. maybe he just manually pushed down a DM multipath table?
And only used the single /dev/nvme0n1 device?  Sagi?