Bug 1465456 - Hot-plugged SCSI-Virtio disk does not receive controlled with correct IO thread
Hot-plugged SCSI-Virtio disk does not receive controlled with correct IO thread
Status: CLOSED WONTFIX
Product: ovirt-engine
Classification: oVirt
Component: BLL.Virt (Show other bugs)
4.1.3.2
x86_64 Linux
unspecified Severity low (vote)
: ovirt-4.3.0
: ---
Assigned To: Michal Skrivanek
meital avital
:
Depends On:
Blocks:
  Show dependency treegraph
 
Reported: 2017-06-27 09:16 EDT by Artyom
Modified: 2017-06-28 02:38 EDT (History)
5 users (show)

See Also:
Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of:
Environment:
Last Closed: 2017-06-28 02:38:13 EDT
Type: Bug
Regression: ---
Mount Type: ---
Documentation: ---
CRM:
Verified Versions:
Category: ---
oVirt Team: Virt
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---
tjelinek: ovirt‑4.3?
tjelinek: planning_ack?
tjelinek: devel_ack?
tjelinek: testing_ack?


Attachments (Terms of Use)
engine and vdsm log (864.59 KB, application/zip)
2017-06-27 09:16 EDT, Artyom
no flags Details

  None (edit)
Description Artyom 2017-06-27 09:16:10 EDT
Created attachment 1292330 [details]
engine and vdsm log

Description of problem:


Version-Release number of selected component (if applicable):


How reproducible:
Always

Steps to Reproduce:
1. Create VM with one SCSI-Virtio disk and 2 IO threads
2. Start the VM
<devices>
    <emulator>/usr/libexec/qemu-kvm</emulator>
    <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <source startupPolicy='optional'/>
      <backingStore/>
      <target dev='hdc' bus='ide'/>
      <readonly/>
      <alias name='ide0-1-0'/>
      <address type='drive' controller='0' bus='1' target='0' unit='0'/>
    </disk>
    <disk type='file' device='disk' snapshot='no'>
      <driver name='qemu' type='raw' cache='none' error_policy='stop' io='threads'/>
      <source file='/rhev/data-center/00000001-0001-0001-0001-000000000311/02ee81e8-c25b-4882-9324-a78793ece745/images/1c453cc3-6e02-4598-bfa6-082bd364daef/3bd1b7d5-cfad-429e-beec-e7e5a8edce60'/>
      <backingStore/>
      <target dev='sda' bus='scsi'/>
      <serial>1c453cc3-6e02-4598-bfa6-082bd364daef</serial>
      <boot order='1'/>
      <alias name='scsi0-0-0-0'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>
    <controller type='usb' index='0' model='piix3-uhci'>
      <alias name='usb'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
    </controller>
    <controller type='scsi' index='0' model='virtio-scsi'>
      <driver iothread='1'/>
      <alias name='scsi0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
    </controller>
    <controller type='scsi' index='1' model='virtio-scsi'>
      <driver iothread='2'/>
      <alias name='scsi1'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </controller>
...
3. Hotplug additional SCSI-Virtio disk to VM
<devices>
    <emulator>/usr/libexec/qemu-kvm</emulator>
    <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <source startupPolicy='optional'/>
      <backingStore/>
      <target dev='hdc' bus='ide'/>
      <readonly/>
      <alias name='ide0-1-0'/>
      <address type='drive' controller='0' bus='1' target='0' unit='0'/>
    </disk>
    <disk type='file' device='disk' snapshot='no'>
      <driver name='qemu' type='raw' cache='none' error_policy='stop' io='threads'/>
      <source file='/rhev/data-center/00000001-0001-0001-0001-000000000311/02ee81e8-c25b-4882-9324-a78793ece745/images/1c453cc3-6e02-4598-bfa6-082bd364daef/3bd1b7d5-cfad-429e-beec-e7e5a8edce60'/>
      <backingStore/>
      <target dev='sda' bus='scsi'/>
      <serial>1c453cc3-6e02-4598-bfa6-082bd364daef</serial>
      <boot order='1'/>
      <alias name='scsi0-0-0-0'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>
    <disk type='file' device='disk' snapshot='no'>
      <driver name='qemu' type='raw' cache='none' error_policy='stop' io='threads'/>
      <source file='/rhev/data-center/00000001-0001-0001-0001-000000000311/02ee81e8-c25b-4882-9324-a78793ece745/images/85465f18-159f-4e69-bda0-0fe9b768a12b/a8ac4c4f-700f-4943-bb56-2320db71a3e3'/>
      <backingStore/>
      <target dev='sdb' bus='scsi'/>
      <serial>85465f18-159f-4e69-bda0-0fe9b768a12b</serial>
      <alias name='scsi0-0-0-2'/>
      <address type='drive' controller='0' bus='0' target='0' unit='2'/>
    </disk>
    <controller type='usb' index='0' model='piix3-uhci'>
      <alias name='usb'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
    </controller>
    <controller type='scsi' index='0' model='virtio-scsi'>
      <driver iothread='1'/>
      <alias name='scsi0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
    </controller>
    <controller type='scsi' index='1' model='virtio-scsi'>
      <driver iothread='2'/>
      <alias name='scsi1'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </controller>
...

Actual results:
Hot-plugged disk has controller with the same IO thread as the first disk

Expected results:
Hot-plugged disk must have controller with different IO thread(sure I talk only about cases when number_of_iothreads > number of disks)

Additional info:
Comment 1 Artyom 2017-06-27 09:17:29 EDT
Versions:
rhevm-4.1.3.2-0.1.el7.noarch
vdsm-4.19.19-1.el7ev.x86_64
Comment 2 Michal Skrivanek 2017-06-28 01:39:19 EDT
doesn't sound like an interesting use case. We do a simple round robin....when ou start doing hot plugs it's no longer simple. 
On top of that - performance improvements for more iothreads seem to be negligent.
WONTFIX?
Comment 3 Yaniv Kaul 2017-06-28 02:38:13 EDT
(In reply to Michal Skrivanek from comment #2)
> doesn't sound like an interesting use case. We do a simple round
> robin....when ou start doing hot plugs it's no longer simple. 
> On top of that - performance improvements for more iothreads seem to be
> negligent.
> WONTFIX?

Yes.

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