On Wed, Sep 24 2014 at 2:34pm -0400, Mike Snitzer <snitzer@xxxxxxxxxx> wrote: > > I never did take the time to properly review Hannes' proposal but now > that you're floating this blk-mq support for DM core (and DM mpath) I'm > clearly going to have to take this all on in a much more focused way. > > Christoph/Hannes/Junichi/Keith/others, can you see a way forward that > offers a lighter request-based DM that makes required callouts to (new?) > block interfaces that helps us abstract the old request and blk-mq > request allocation, etc? (sorry about replying to myself...) SO revisiting that thread from above, these posts stand out: http://www.redhat.com/archives/dm-devel/2014-June/msg00026.html http://www.redhat.com/archives/dm-devel/2014-June/msg00028.html I'd love to see us get rid of request-based DM's bio cloning for each cloned request (we never did get an answer from the NEC guys to know _why_ that was done). http://www.redhat.com/archives/dm-devel/2014-June/msg00029.html But I now see what Christoph was saying about needing the call blk_get_request() against the low level path... and that completely avoiding request cloning like Hannes did is a non-starter for blk-mq. So if we could: 1) rip out the rq-based DM's cloning of all bios in a request 2) rebase Keith's approach ontop of 1) then we could go from there - but happy to put more thought in upfront to avoid busy work; and I'd encourage everyone else to do the same... -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
