Re: v4.16-rc1 + dm-mpath + BFQ

[Laurence Oberman <loberman@redhat.com>]

On Thu, 2018-05-10 at 15:16 +0000, Bart Van Assche wrote:
> On Fri, 2018-05-04 at 16:42 -0400, Laurence Oberman wrote:
> > I was never able to reproduce Barts original issue using his tree
> > and
> > actual mlx5/cx4 hardware and ibsrp
> > I enabled BFQ with no other special tuning for the moath and
> > subpaths.
> > I was waiting for him to come back from vacation to check with him.
> 
> (back in the office)
> 
> Hello Laurence,
> 
> What I understood from off-list communication is that you tried to
> find
> a way to reproduce what I reported without using the srp-test
> software.
> My understanding is that both Paolo and I can reproduce the reported
> issue
> with the srp-test software.
> 
> Bart.
> 
> 
> 

Hello Bart

using your kernel
4.17.0-rc2.bart+

CONFIG_IOSCHED_BFQ=y
CONFIG_BFQ_GROUP_IOSCHED=y

These are all SRP LUNS

36001405b2b5c6c24c084b6fa4d55da2f dm-27 LIO-ORG ,block-10        
size=3.9G features='2 queue_mode mq' hwhandler='0' wp=rw
`-+- policy='service-time 0' prio=1 status=active
  |- 2:0:0:9  sdap 66:144 active ready running
  `- 1:0:0:9  sdaz 67:48  active ready running

36001405b26ebe76dcb94a489f6f245f8 dm-18 LIO-ORG ,block-21        
size=3.9G features='2 queue_mode mq' hwhandler='0' wp=rw
`-+- policy='service-time 0' prio=1 status=active
  |- 2:0:0:20 sdx  65:112 active ready running
  `- 1:0:0:20 sdaa 65:160 active ready running

[root@ibclient ~]# cd /sys/block
[root@ibclient block]# cat /sys/block/dm-18/queue/scheduler
mq-deadline kyber [bfq] none
[root@ibclient block]# cat /sys/block/sdaa/queue/scheduler
mq-deadline kyber [bfq] none
[root@ibclient block]# cat /sys/block/sdx/queue/scheduler
mq-deadline kyber [bfq] none

Not using the test software just exercising the LUNS via my own tests I
am unable to get the OOPS

I guess something in the srp-test software triggers it then.

Doing plenty of IO to 5 mpath devices (1.3Gbytes/sec)

#Time     cpu sys inter  ctxsw Free Buff Cach Inac Slab  Map
KBRead  Reads KBWrit Writes   KBIn  PktIn  KBOut  PktOut 
12:08:32    0   0  1437   1107  88G   5M   1G 902M 300M
178M  1380K    345      0      0      6     74      0       4 

Thanks
Laurence