Instable domU on debian stretch

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Instable domU on debian stretch

jaap-2
I experience instability of my xen domUs.
The following error is raised:

[190190.556098] INFO: task jbd2/xvda7-8:409 blocked for more than 120
seconds.

Sometimes, other devices block.

The error started to appear after upgrading to debian stretch.
I run Xen version 4.8.1 (Debian 4.8.1-1+deb9u1), all DomUs on SSD.

Kernel hypervisor
4.9.0-3-amd64 #1 SMP Debian 4.9.30-2+deb9u1 (2017-06-18) x86_64 GNU/Linux
Kernel domU
4.9.0-3-amd64 #1 SMP Debian 4.9.30-2+deb9u3 (2017-08-06) x86_64 GNU/Linux

The configuration file voor DomU:
***
bootloader = '/usr/lib/xen-4.6/bin/pygrub'
vcpus       = '4'
memory      = '12288'
root        = '/dev/xvda2 ro'
disk        = [
                  'phy:/dev/vm/root,xvda2,w',
                  'phy:/dev/vm/var,xvda5,w',
                  'phy:/dev/vm/tmp,xvda4,w',
                  'phy:/dev/vm/opt,xvda3,w',
                  'phy:/dev/vm/swap,xvda1,w',
                  'phy:/dev/data/home,xvda6,w',
                  'phy:/dev/data/data,xvda7,w'
              ]

name        = 'pdc'
vif         = [ 'ip=192.168.30.12 ,mac=xx:xx:xx:xx:xx:xx,bridge=xenbr0.30' ]
pvh         = 1
on_poweroff = 'destroy'
on_reboot   = 'restart'
on_crash    = 'restart'
vnc=1
***

I tried to do the following (as recommended many times on the Internet):

on DomU:
# hung_task_timeout_secs - task jbd2/xvda blocked for more than 120 seconds
vm.dirty_background_ratio = 5
vm.dirty_ratio = 5

on Dom0:
#
https://discussions.citrix.com/topic/272708-xen-block-devices-stop-respondin
g-in-guest/
vm.swappiness = 0
vm.overcommit_memory = 1
vm.dirty_expire_centisecs = 1000
vm.dirty_background_ratio = 5
vm.dirty_ratio = 5

However, I still get blocking messages.



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Re: Instable domU on debian stretch

Roger Pau Monné-3
On Sun, Sep 10, 2017 at 11:34:36AM +0200, [hidden email] wrote:
> I experience instability of my xen domUs.
> The following error is raised:
>
> [190190.556098] INFO: task jbd2/xvda7-8:409 blocked for more than 120
> seconds.

On the Dom0, can you try setting the following parameters:

# echo 2 > /sys/module/xen_blkback/parameters/max_queues
# echo 300 > /sys/module/xen_blkback/parameters/max_persistent_grants

And reboot your DomU?

Roger.

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Re: Instable domU on debian stretch

Roger Pau Monné-3
Please don't top post and don't drop xen-users.

On Sun, Sep 17, 2017 at 12:09:11PM +0200, Jaap Gordijn wrote:
> Thanks
>
> Any idea how to make this permanent?
> If I try to execute this command before the relevant Dom is loaded, the driver seems not be loaded yet,
> So I can't enter the relevant commands.

You need to do this on the Dom0, not the DomU. Just do it anytime
before creating the DomU.

Roger.

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