On Mon, Jan 25 2016 at 6:37pm -0500, Benjamin Marzinski <bmarzins@xxxxxxxxxx> wrote: > On Mon, Jan 25, 2016 at 04:40:16PM -0500, Mike Snitzer wrote: > > On Tue, Jan 19 2016 at 5:45P -0500, > > Mike Snitzer <snitzer@xxxxxxxxxx> wrote: > > I don't think this is going to help __multipath_map() without some > configuration changes. Now that we're running on already merged > requests instead of bios, the m->repeat_count is almost always set to 1, > so we call the path_selector every time, which means that we'll always > need the write lock. Bumping up the number of IOs we send before calling > the path selector again will give this patch a change to do some good > here. > > To do that you need to set: > > rr_min_io_rq <something_bigger_than_one> > > in the defaults section of /etc/multipath.conf and then reload the > multipathd service. > > The patch should hopefully help in multipath_busy() regardless of the > the rr_min_io_rq setting. This patch, while generic, is meant to help the blk-mq case. A blk-mq request_queue doesn't have an elevator so the requests will not have seen merging. But yes, implied in the patch is the requirement to increase m->repeat_count via multipathd's rr_min_io_rq (I'll backfill a proper header once it is tested). Thanks, Mike -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
