Hi Darrel,

Still, based on my experience we shouldn't queue our I/O in the VM, just to do the same in the Host.

I'm still considering if I should keep deadline  in my hosts or to switch to 'cfq'.
After all, I'm using Hyper-converged oVirt and this needs testing.
What I/O scheduler  are  you using on the  host?

Best Regards,
Strahil Nikolov

On Mar 18, 2019 19:15, Darrell Budic <budic@onholyground.com> wrote:
Checked this on mine, see the same thing. Switching the engine to noop definitely feels more responsive.

I checked on some VMs as well, it looks like virtio drives (vda, vdb….) get mq-deadline by default, but virtscsi gets noop. I used to think the tuned profile for virtual-guest would set noop, but apparently not…

  -Darrell

On Mar 18, 2019, at 1:58 AM, Strahil Nikolov <hunter86_bg@yahoo.com> wrote:

Hi All,

I have changed my I/O scheduler to none and here are the results so far:

Before (mq-deadline):
Adding a disk to VM (initial creation) START:     2019-03-17 16:34:46.709
Adding a disk to VM (initial creation) COMPLETED: 2019-03-17 16:45:17.996

After (none):
Adding a disk to VM (initial creation) START:     2019-03-18 08:52:02.xxx
Adding a disk to VM (initial creation) COMPLETED: 2019-03-18 08:52:20.xxx

Of course the results are inconclusive, as I have tested only once - but I feel the engine more responsive.

Best Regards,
Strahil Nikolov

В неделя, 17 март 2019 г., 18:30:23 ч. Гринуич+2, Strahil <hunter86_bg@yahoo.com> написа:


Dear All,

I have just noticed that my Hosted Engine has  a strange I/O scheduler:

Last login: Sun Mar 17 18:14:26 2019 from 192.168.1.43
[root@engine ~]# cat /sys/block/vda/queue/scheduler
[mq-deadline] kyber none
[root@engine ~]#

Based on my experience  anything than noop/none  is useless and performance degrading  for a VM.

Is there any reason that we have this scheduler ?
It is quite pointless  to process (and delay) the I/O in the VM and then process (and again delay)  on Host Level .

If there is no reason to keep the deadline, I will open a bug about it.

Best Regards,
Strahil Nikolov

Dear All,

I have just noticed that my Hosted Engine has  a strange I/O scheduler:

Last login: Sun Mar 17 18:14:26 2019 from 192.168.1.43
[root@engine ~]# cat /sys/block/vda/queue/scheduler
[mq-deadline] kyber none
[root@engine ~]#

Based on my experience  anything than noop/none  is useless and performance degrading  for a VM.