[libvirt] 'dommemstat' is not working for LXC hypervisor.

Ryota Ozaki ozaki.ryota at gmail.com
Thu Apr 29 12:43:47 UTC 2010


On Thu, Apr 29, 2010 at 9:32 PM, Kumar L Srikanth-B22348
<B22348 at freescale.com> wrote:
> Now it's showing Used Memory as 0. I don't know whether it's correct or not.
> I wrote a small script in the domain to check the used memory, which will run continuously in the infinite loop.
> dominfo 'domainname' is showing Used Memory as 0.
> Is this right way to check the Used Memory of that domain?

dominfo should be...but something wrong.

In my machine, dominfo shows like:

# virsh -c lxc:/// dominfo 31105
Id:             31105
Name:           cl_lxc_test
UUID:           fd7b21d9-6cbb-17a8-53dd-233f0aed4b4a
OS Type:        exe
State:          running
CPU(s):         1
CPU time:       3.0s
Max memory:     131072 kB
Used memory:    23672 kB
Autostart:      disable

However, the version of libvirt is not 0.8.0. So I try to check
what changed by recent updates.

Thanks,
  ozaki-r


>
> Regards,
> Srikanth.
>
> -----Original Message-----
> From: Ryota Ozaki [mailto:ozaki.ryota at gmail.com]
> Sent: Thursday, April 29, 2010 5:50 PM
> To: Kumar L Srikanth-B22348
> Cc: Daniel P. Berrange; libvirt list; Ryota OZAKI
> Subject: Re: [libvirt] 'dommemstat' is not working for LXC hypervisor.
>
> On Thu, Apr 29, 2010 at 9:14 PM, Kumar L Srikanth-B22348 <B22348 at freescale.com> wrote:
>> Thanks ozaki.
>> But can you please elaborate the process of getting memory.stat of a particular domain?
>> I mounted cgroup filesystem prior to start libvirtd service using the below command:
>> mount -t cgroup cgroup /cgroup
>>
>> Then started libvirtd service.
>> Then started the domain.
>>
>> Here, can you let me know the process of viewing memory stats of that particular domain?
>
> Could you check output of dominfo again. Cannot you get proper 'Used memory'?
>
>> By the way, in the /cgroup directory lot of files are created. In those, which one can be memory stats?
>
> /cgroup/memory.stat is.
>
>  ozaki-r
>
>>
>> Regards,
>> Srikanth.
>>
>> -----Original Message-----
>> From: Ryota Ozaki [mailto:ozaki.ryota at gmail.com]
>> Sent: Thursday, April 29, 2010 5:27 PM
>> To: Kumar L Srikanth-B22348
>> Cc: Daniel P. Berrange; libvirt list; Ryota OZAKI
>> Subject: Re: [libvirt] 'dommemstat' is not working for LXC hypervisor.
>>
>> On Wed, Apr 28, 2010 at 8:19 PM, Kumar L Srikanth-B22348 <B22348 at freescale.com> wrote:
>>> Daniel,
>>> My requirement is to get how much memory is free in the guest domain.
>>> Can you please let me know, how can I do that?
>>
>> Do you enable cgroup memory subsystem? If so, something wrong in lxc driver of 0.8.0.
>>
>> BTW, 'Used memory' includes both RSS and caches, so if you need total-RSS value, you should use dommemstat.
>>
>>> And also, as you said it's quite easy to implement dommemstats for
>>> lxc driver, is there any possibility to implement that?
>>
>> We can get statistics of dommemstat easily through memory.stat of cgroup.memory subsystem except statistics of page faults.
>>
>>  ozaki-r
>>
>>>
>>> Regards,
>>> Srikanth.
>>>
>>> -----Original Message-----
>>> From: Daniel P. Berrange [mailto:berrange at redhat.com]
>>> Sent: Wednesday, April 28, 2010 4:46 PM
>>> To: Kumar L Srikanth-B22348
>>> Cc: libvir-list at redhat.com
>>> Subject: Re: 'dommemstat' is not working for LXC hypervisor.
>>>
>>> On Wed, Apr 28, 2010 at 04:43:41PM +0530, Kumar L Srikanth-B22348 wrote:
>>>> Thanks for the reply Daniel.
>>>> Virsh dominfo dommand showing following results:
>>>>
>>>> Id:             32473
>>>> Name:           vm1
>>>> UUID:           f13bc513-15f2-1dd1-74f6-18c47931ece9
>>>> OS Type:        exe
>>>> State:          running
>>>> CPU(s):         1
>>>> Max memory:     5000000 kB
>>>> Used memory:    5000000 kB
>>>> Autostart:      disable
>>>>
>>>>
>>>> Though whatever services running on the domain, every time used
>>>> memory
>>>
>>>> is showing as 5000000 kB. Is that result is correct?
>>>
>>> The 'Max memory' 5000000 KB is the hard limit that is allocated to
>>> the container. I thought that the 'used memory' field would be lower,
>>> but its possible we don't have the actual stats for used memory so
>>> just set both the same. I'd have to research the code again to answer for sure...
>>>
>>> Daniel
>>> --
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>>> |7D3B
>>> 9505 :|
>>>
>>>
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>>
>>
>
>




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