On Mon, Jan 12 2015 at 12:04pm -0500, Bart Van Assche <bart.vanassche@xxxxxxxxxxx> wrote: > On 01/12/15 17:34, Jens Axboe wrote: > > > > So that does look a bit off, we have (supposedly) 9 active requests, but > > nothing allocated. When the mkfs is done and things are idle, can you > > try and cat the 'active' file in the mq directory? I want to see if it > > drops to zero or stays elevated. > > Hello Jens, > > Sorry that I hadn't been more clear but the __bt_get() data in the > previous e-mail was gathered when multipathd started instead of when > mkfs was started. That was the time at which Mike's debug patch reported > for the first time that __bt_get() returned -1. What is also remarkable > is that all "__bt_get() returned -1" reports that I checked referred to > the /dev/dm-0 device and none to any of the underlying devices > (/dev/sd[cd]). That cannot be, considering the request-based DM device (dm-0) isn't a blk-mq device (so it never calls into __bt_get). How did you draw that conclusion? > The tag state after having stopped multipathd (systemctl stop > multipathd) is as follows: > # dmsetup table /dev/dm-0 > 0 256000 multipath 3 queue_if_no_path pg_init_retries 50 0 1 1 > service-time 0 2 2 8:48 1 1 8:32 1 1 > # ls -l /dev/sd[cd] > brw-rw---- 1 root disk 8, 32 Jan 12 17:47 /dev/sdc > brw-rw---- 1 root disk 8, 48 Jan 12 17:47 /dev/sdd > # for d in sdc sdd dm-0; do echo ==== $d; (cd /sys/block/$d/mq && > find|cut -c3-|grep active|xargs grep -aH ''); done > ==== sdc > 0/active:10 > 1/active:14 > 2/active:7 > 3/active:13 > 4/active:6 > 5/active:10 > ==== sdd > 0/active:17 > 1/active:8 > 2/active:9 > 3/active:13 > 4/active:5 > 5/active:10 > ==== dm-0 > -bash: cd: /sys/block/dm-0/mq: No such file or directory Confirms dm-0 isn't blk-mq device. Making request-based DM use blk-mq is certainly something I intend to look at. But the current dm-multipath is using old request-based queue (dm-0) in front of underlying blk-mq devices (sdc, sdd) as the first step. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
