[Bug 1597610] Comment bridged from LTC Bugzilla

[bugproxy]

------- Comment From jhopper at us.ibm.com 2016-07-25 15:58 EDT-------
I edited the description in launchpad to include the following:

[Impact]

By default, currently Power guests are defined with bus=?scsi? disk
type. Virtio disks will perform much better in KVM environments than the
scsi (papr) model so the default should be changed to improve out-of-
the-box guest performance.

[Test Case]

Create a guest using virt-install or virt-manager, check the default
disk type with ?virsh dumpxml <guest>?.

Ex. virt-install command:
virt-install --force --name test --ram 4096 --vcpus 4 --location <location path> --noautoconsole --wait=-1 --noreboot --nographic --disk path=/var/lib/libvirt/images/test.raw,size=10

[Regression Potential]

Virtio tends to get more test cycles in general, so changing the default
may actually reduce the risk of regressions with the papr scsi type.

[Other Info]

All guests that can run on Power support the virtio-blk disk type.

--
Also removing the network portion from the bug title, we will need to follow up on that later once changes make their way upstream.

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https://bugs.launchpad.net/bugs/1597610

Title:
  virt-install default to virtio type - disk

Status in virt-manager package in Ubuntu:
  In Progress

Bug description:
  == Comment: #0 - JENIFER HOPPER <jhopper at us.ibm.com> - 2016-06-28 11:58:08 ==
  ---Problem Description---
  For best performance, we would like Power guests to default to virtio for disk and network type when using virt-install. All supported ppc64le guest OSes have virtio support.

  For the disk default, there is an upstream commit:

  commit f6322c9ed8e6d38083e6365ab9f08e5a09d147be
  Author: Shivaprasad G Bhat <sbhat at linux.vnet.ibm.com>
  Date:   Thu Apr 21 13:30:34 2016 +0530

      virtinst: Use virtio bus type for disks on pSeries machines

      pSeries doesn't support ide and so was changed to use the scsi.
  virtio works better on pSeries with better performance outcomes.
  Change the default to virtio for disks

      Signed-off-by: Shivaprasad G Bhat <sbhat at linux.vnet.ibm.com>

  http://www.spinics.net/lists/virt-tools/msg09433.html

  --

  I am checking on the current upstream status for the network default.
  Looks like right now on 16.04, virt-install defaults to rtl8139 even if --os-variant is used.

  ---uname output---
  Linux p82qvirt 4.4.0-24-generic #43-Ubuntu SMP Wed Jun 8 19:25:36 UTC 2016 ppc64le ppc64le ppc64le GNU/Linux

  Machine Type = 8247-22L

  ---Debugger---
  A debugger is not configured

  ---Steps to Reproduce---
   Start a guest using virt-install using all defaults.

  # dpkg -l | grep virtinst
  ii  virtinst                           1:1.3.2-3ubuntu1.16.04.1            all          Programs to create and clone virtual machines

  Contact Information = jhopper at us.ibm.com

  == Comment: #4 - Shivaprasad G. Bhat <shivapbh at in.ibm.com> - 2016-06-29 03:32:28 ==
  Hi Jennifer,

  The below patch also needs to pulled into Ubuntu as the CDROMs cannot work on virtio bus on PPC.
  https://github.com/virt-manager/virt-manager/commit/94f610465f45264142ff5def7b5ceaf9ecfe065b

  Thanks,
  Shiva

  == Comment: #8 - SANDHYA VENUGOPALA <vsandhya at in.ibm.com> - 2016-06-30 01:21:01 ==
  Canonical,

  Please include the upstream disk and cdrom patches listed in this bug
  report.

  please note that network portion is still a work in progress and a
  patch will made available for inclusion soon.

  Changing the network default would significantly help out of the box
  performance, but as of now many users are probably aware that virtio
  is a good tuning option.

  --
  [Impact] 

  By default, currently Power guests are defined with bus=‘scsi’ disk
  type. Virtio disks will perform much better in KVM environments than
  the scsi (papr) model so the default should be changed to improve out-
  of-the-box guest performance.

  [Test Case]

  Create a guest using virt-install or virt-manager, check the default
  disk type with “virsh dumpxml <guest>”.

  Ex. virt-install command:
   virt-install --force --name test --ram 4096 --vcpus 4 --location <location path> --noautoconsole --wait=-1 --noreboot --nographic --disk path=/var/lib/libvirt/images/test.raw,size=10 

  
  [Regression Potential] 

  Virtio tends to get more test cycles in general, so changing the
  default may actually reduce the risk of regressions with the papr scsi
  type.

  [Other Info]
   
  All guests that can run on Power support the virtio-blk disk type.

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