Re: [vdsm] reserve virtio-balloon device created by libvirt

2012-04-30 Thread Itamar Heim

On 04/29/2012 04:19 PM, Dan Kenigsberg wrote:

On Sun, Apr 29, 2012 at 07:24:52AM -0400, Andrew Cathrow wrote:



- Original Message -

From: Dan Kenigsbergdan...@redhat.com
To: Gal Hammergham...@redhat.com
Cc: vdsm-devel@lists.fedorahosted.org
Sent: Sunday, April 29, 2012 7:19:10 AM
Subject: Re: [vdsm] reserve virtio-balloon device created by libvirt

On Mon, Apr 23, 2012 at 04:00:55PM +0300, Gal Hammer wrote:

On 23/04/2012 12:26, Mark Wu wrote:

Hi guys,

I saw that an option to create balloon device was added by Gal in
http://gerrit.ovirt.org/1573
I have a question about it. Why don we preserve the old default
behaviour? I know it's not supported by ovirt-engine now, but I
can't
figure out what will break if it's not disabled explicitly. So do
you
think we can just make use of the balloon device added by libvirt?


We didn't change the old behavior.

Libvirt creates by default a memory-balloon device, so vdsm
defaults
was to disable it by adding a none-type device. This was done
because vdsm didn't include an option to add such device.

My patch added an option to create a memory-balloon through vdsm.
If
the user didn't request to add the device, the behavior is same as
before, disabling the memory-balloon.


I feel that it would be best not to flip Vdsm's default at the
moment,
even though it is the opposite of libvirt's. I would consider to flip
them only after your (Mark's) patches are in, tested, and proven
worthwhile for the common case.

Currently, without any management for the balloon, reserving a guest
PCI
device was deemed wasteful.


On the other side of the fence
- We know that we do need to do ballooning
- In the (next?) release we'll end up adding this support
- There's no harm (see next point) in adding the device now in fact it saves a 
config change on upgrade.


Well, there is a surprise factor, for someone running a guest generated
in a previous version. Suddenly, after Vdsm upgrade, it would see an
additional device. At the least, I would like Vdsm to have a
configurable option to keep the old behavior.


please take into consideration engine has an algorithm testing max 
number of devices and it should be aware of newly introduced devices by 
vdsm or it will overflow.





- While it takes up a PCI slot it's going to be very, very rare deployments 
that will ever see the limit, libvirt/virtmanager/virt-install has done this 
forever without seeing push back.



___
vdsm-devel mailing list
vdsm-devel@lists.fedorahosted.org
https://fedorahosted.org/mailman/listinfo/vdsm-devel


___
vdsm-devel mailing list
vdsm-devel@lists.fedorahosted.org
https://fedorahosted.org/mailman/listinfo/vdsm-devel


Re: [vdsm] reserve virtio-balloon device created by libvirt

2012-04-30 Thread Dor Laor

On 04/30/2012 07:30 PM, Itamar Heim wrote:

On 04/29/2012 04:19 PM, Dan Kenigsberg wrote:

On Sun, Apr 29, 2012 at 07:24:52AM -0400, Andrew Cathrow wrote:



- Original Message -

From: Dan Kenigsbergdan...@redhat.com
To: Gal Hammergham...@redhat.com
Cc: vdsm-devel@lists.fedorahosted.org
Sent: Sunday, April 29, 2012 7:19:10 AM
Subject: Re: [vdsm] reserve virtio-balloon device created by libvirt

On Mon, Apr 23, 2012 at 04:00:55PM +0300, Gal Hammer wrote:

On 23/04/2012 12:26, Mark Wu wrote:

Hi guys,

I saw that an option to create balloon device was added by Gal in
http://gerrit.ovirt.org/1573
I have a question about it. Why don we preserve the old default
behaviour? I know it's not supported by ovirt-engine now, but I
can't
figure out what will break if it's not disabled explicitly. So do
you
think we can just make use of the balloon device added by libvirt?


We didn't change the old behavior.

Libvirt creates by default a memory-balloon device, so vdsm
defaults
was to disable it by adding a none-type device. This was done
because vdsm didn't include an option to add such device.

My patch added an option to create a memory-balloon through vdsm.
If
the user didn't request to add the device, the behavior is same as
before, disabling the memory-balloon.


I feel that it would be best not to flip Vdsm's default at the
moment,
even though it is the opposite of libvirt's. I would consider to flip
them only after your (Mark's) patches are in, tested, and proven
worthwhile for the common case.

Currently, without any management for the balloon, reserving a guest
PCI
device was deemed wasteful.


On the other side of the fence
- We know that we do need to do ballooning
- In the (next?) release we'll end up adding this support
- There's no harm (see next point) in adding the device now in fact
it saves a config change on upgrade.


Well, there is a surprise factor, for someone running a guest generated


surprise == another minor reason for windows guest to re-activate.


in a previous version. Suddenly, after Vdsm upgrade, it would see an
additional device. At the least, I would like Vdsm to have a
configurable option to keep the old behavior.


In qemu we have a compatibility level controlled by -M flag.
VDSM should have a similar compatibility level and defaults shouldn't 
normally change in minor releases.




please take into consideration engine has an algorithm testing max
number of devices and it should be aware of newly introduced devices by
vdsm or it will overflow.


It is good timing to change the algorithm too. IIRC the algorithm has 
some hard coded assumptions about qemu. Instead, it would be better to 
consult w/ qemu in run time and get the free pci slots number and any 
other limits. Soon qemu will support pci bridges and this will increase 
the number of pci devices and virtio-scsi will insert some other 
calculation factor.







- While it takes up a PCI slot it's going to be very, very rare
deployments that will ever see the limit,
libvirt/virtmanager/virt-install has done this forever without seeing
push back.



___
vdsm-devel mailing list
vdsm-devel@lists.fedorahosted.org
https://fedorahosted.org/mailman/listinfo/vdsm-devel


___
Engine-devel mailing list
engine-de...@ovirt.org
http://lists.ovirt.org/mailman/listinfo/engine-devel


___
vdsm-devel mailing list
vdsm-devel@lists.fedorahosted.org
https://fedorahosted.org/mailman/listinfo/vdsm-devel


Re: [vdsm] reserve virtio-balloon device created by libvirt

2012-04-29 Thread Dan Kenigsberg
On Mon, Apr 23, 2012 at 04:00:55PM +0300, Gal Hammer wrote:
 On 23/04/2012 12:26, Mark Wu wrote:
 Hi guys,
 
 I saw that an option to create balloon device was added by Gal in
 http://gerrit.ovirt.org/1573
 I have a question about it. Why don we preserve the old default
 behaviour? I know it's not supported by ovirt-engine now, but I can't
 figure out what will break if it's not disabled explicitly. So do you
 think we can just make use of the balloon device added by libvirt?
 
 We didn't change the old behavior.
 
 Libvirt creates by default a memory-balloon device, so vdsm defaults
 was to disable it by adding a none-type device. This was done
 because vdsm didn't include an option to add such device.
 
 My patch added an option to create a memory-balloon through vdsm. If
 the user didn't request to add the device, the behavior is same as
 before, disabling the memory-balloon.

I feel that it would be best not to flip Vdsm's default at the moment,
even though it is the opposite of libvirt's. I would consider to flip
them only after your (Mark's) patches are in, tested, and proven
worthwhile for the common case.

Currently, without any management for the balloon, reserving a guest PCI
device was deemed wasteful.

Regards,

Dan.



___
vdsm-devel mailing list
vdsm-devel@lists.fedorahosted.org
https://fedorahosted.org/mailman/listinfo/vdsm-devel


Re: [vdsm] reserve virtio-balloon device created by libvirt

2012-04-29 Thread Andrew Cathrow


- Original Message -
 From: Dan Kenigsberg dan...@redhat.com
 To: Gal Hammer gham...@redhat.com
 Cc: vdsm-devel@lists.fedorahosted.org
 Sent: Sunday, April 29, 2012 7:19:10 AM
 Subject: Re: [vdsm] reserve virtio-balloon device created by libvirt
 
 On Mon, Apr 23, 2012 at 04:00:55PM +0300, Gal Hammer wrote:
  On 23/04/2012 12:26, Mark Wu wrote:
  Hi guys,
  
  I saw that an option to create balloon device was added by Gal in
  http://gerrit.ovirt.org/1573
  I have a question about it. Why don we preserve the old default
  behaviour? I know it's not supported by ovirt-engine now, but I
  can't
  figure out what will break if it's not disabled explicitly. So do
  you
  think we can just make use of the balloon device added by libvirt?
  
  We didn't change the old behavior.
  
  Libvirt creates by default a memory-balloon device, so vdsm
  defaults
  was to disable it by adding a none-type device. This was done
  because vdsm didn't include an option to add such device.
  
  My patch added an option to create a memory-balloon through vdsm.
  If
  the user didn't request to add the device, the behavior is same as
  before, disabling the memory-balloon.
 
 I feel that it would be best not to flip Vdsm's default at the
 moment,
 even though it is the opposite of libvirt's. I would consider to flip
 them only after your (Mark's) patches are in, tested, and proven
 worthwhile for the common case.
 
 Currently, without any management for the balloon, reserving a guest
 PCI
 device was deemed wasteful.

On the other side of the fence 
- We know that we do need to do ballooning
- In the (next?) release we'll end up adding this support
- There's no harm (see next point) in adding the device now in fact it saves a 
config change on upgrade.
- While it takes up a PCI slot it's going to be very, very rare deployments 
that will ever see the limit, libvirt/virtmanager/virt-install has done this 
forever without seeing push back.
 
 Regards,
 
 Dan.
 
 
 
 ___
 vdsm-devel mailing list
 vdsm-devel@lists.fedorahosted.org
 https://fedorahosted.org/mailman/listinfo/vdsm-devel
 
___
vdsm-devel mailing list
vdsm-devel@lists.fedorahosted.org
https://fedorahosted.org/mailman/listinfo/vdsm-devel


Re: [vdsm] reserve virtio-balloon device created by libvirt

2012-04-29 Thread Dan Kenigsberg
On Sun, Apr 29, 2012 at 07:24:52AM -0400, Andrew Cathrow wrote:
 
 
 - Original Message -
  From: Dan Kenigsberg dan...@redhat.com
  To: Gal Hammer gham...@redhat.com
  Cc: vdsm-devel@lists.fedorahosted.org
  Sent: Sunday, April 29, 2012 7:19:10 AM
  Subject: Re: [vdsm] reserve virtio-balloon device created by libvirt
  
  On Mon, Apr 23, 2012 at 04:00:55PM +0300, Gal Hammer wrote:
   On 23/04/2012 12:26, Mark Wu wrote:
   Hi guys,
   
   I saw that an option to create balloon device was added by Gal in
   http://gerrit.ovirt.org/1573
   I have a question about it. Why don we preserve the old default
   behaviour? I know it's not supported by ovirt-engine now, but I
   can't
   figure out what will break if it's not disabled explicitly. So do
   you
   think we can just make use of the balloon device added by libvirt?
   
   We didn't change the old behavior.
   
   Libvirt creates by default a memory-balloon device, so vdsm
   defaults
   was to disable it by adding a none-type device. This was done
   because vdsm didn't include an option to add such device.
   
   My patch added an option to create a memory-balloon through vdsm.
   If
   the user didn't request to add the device, the behavior is same as
   before, disabling the memory-balloon.
  
  I feel that it would be best not to flip Vdsm's default at the
  moment,
  even though it is the opposite of libvirt's. I would consider to flip
  them only after your (Mark's) patches are in, tested, and proven
  worthwhile for the common case.
  
  Currently, without any management for the balloon, reserving a guest
  PCI
  device was deemed wasteful.
 
 On the other side of the fence 
 - We know that we do need to do ballooning
 - In the (next?) release we'll end up adding this support
 - There's no harm (see next point) in adding the device now in fact it saves 
 a config change on upgrade.

Well, there is a surprise factor, for someone running a guest generated
in a previous version. Suddenly, after Vdsm upgrade, it would see an
additional device. At the least, I would like Vdsm to have a
configurable option to keep the old behavior.

 - While it takes up a PCI slot it's going to be very, very rare deployments 
 that will ever see the limit, libvirt/virtmanager/virt-install has done this 
 forever without seeing push back.


___
vdsm-devel mailing list
vdsm-devel@lists.fedorahosted.org
https://fedorahosted.org/mailman/listinfo/vdsm-devel


Re: [vdsm] reserve virtio-balloon device created by libvirt

2012-04-23 Thread Gal Hammer

On 23/04/2012 12:26, Mark Wu wrote:

Hi guys,

I saw that an option to create balloon device was added by Gal in
http://gerrit.ovirt.org/1573
I have a question about it. Why don we preserve the old default
behaviour? I know it's not supported by ovirt-engine now, but I can't
figure out what will break if it's not disabled explicitly. So do you
think we can just make use of the balloon device added by libvirt?


We didn't change the old behavior.

Libvirt creates by default a memory-balloon device, so vdsm defaults was 
to disable it by adding a none-type device. This was done because vdsm 
didn't include an option to add such device.


My patch added an option to create a memory-balloon through vdsm. If the 
user didn't request to add the device, the behavior is same as before, 
disabling the memory-balloon.


Gal.


Thanks!
Mark



___
vdsm-devel mailing list
vdsm-devel@lists.fedorahosted.org
https://fedorahosted.org/mailman/listinfo/vdsm-devel