[fedora-virt] Virtualization Test Day

Chris Lalancette clalance at redhat.com
Thu May 7 15:04:20 UTC 2009

Dale Bewley wrote:
> ----- "Chris Lalancette" <clalance at redhat.com> wrote:
>> Dale Bewley wrote:
>>> Already been poking![1] But now it's bed time. Hopefully I can do
>> some more testing tomorrow.
>>> [1]
>> http://fedoraproject.org/wiki/User:Dale/Test_Day:2009-05-07_Virtualization:XenDomU
>> Thanks a lot for starting in on this!  Quick question about your ballooning
>>  results; did you remember to balloon down the dom0 before trying to 
>> balloon up your guest?  It doesn't do it automatically on when you run the
>> "virsh setmem" command.
> Actually I did not modify the dom0. Can you take a peek at the discussion
> page[1]? Perhaps the test case could be clarified a little bit.
> Is step 1 run in the dom0?

No, that's in the domU.

> Is step 2 modifying xend to affect dom0 or a guest config? I assumed the
> latter but guest configs aren't there anymore.

Yes, that's right, it's for changing the guest configuration.

> Just in case, I did try shrinking Domain-0 and testing again.
> [root at felix tmp]# virsh dominfo Domain-0 ... Max memory:     no limit Used
> memory:    5181440 kB
> [root at felix tmp]# virst setmem Domain-0 $(( 1024 * 3000 ))
> [root at felix tmp]# virsh dominfo Domain-0 ... Max memory:     no limit Used
> memory:    3072000 kB
> But I could not setmem to a value higher than <maxmem> of the domU config. 
> [root at felix tmp]# virsh setmem f11-32 $(( 1024 * 2000 )) error: Invalid value
> of 2048000 for memory size
> I could balloon to values between <currentMemory> and <maxmem>, and 'xm list
> f11-32' would show the expected value, but the guest would not show more than
> <currentMemory>. So apparently I misunderstood the meaning of that element.
> I just tested another domU and I'll update my notes later, but:
> * If it's assumed that <currentMemory> should not be used for this test
> (contrary to what I put on the discusson page), and that you can't balloon a
> guest beyond <maxmem> then everything works fine. I can shrink and grow below
> <maxmem> with no issues.
> * If it's expected you can balloon to values between <currentMemory> and
> <maxmem>, then something may be wrong.

Yeah, I also tested it, and it's definitely a bug.  You should be able to
balloon anywhere between the value of 0 (OK, that would be stupid, but should
exist in theory) and "<maxmem>", inclusive.  I've filed
http://bugzilla.redhat.com/499587 to track it.  Thanks for testing it out again.

Chris Lalancette

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