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



On Thu, Apr 29, 2010 at 10:23 PM, Ryota Ozaki <ozaki ryota gmail com> wrote:
> On Thu, Apr 29, 2010 at 9:54 PM, Kumar L Srikanth-B22348
> <B22348 freescale com> wrote:
>> Thanks Ozaki.
>> Please let me know the result, once you checked with 0.8.0.
>
> I may understand what happen.
>
> Could you check 'tree -d /cgroup' where running your domain
> and could you find that a directory named your domain
> has another directory named some numeric number?
>
> If so, could you try cgroup without ns subsystem like
> mount -t cgroup -o cpu,cpuacct,cpuset,memory,devices cgroup /cgroup
> or something.
>
> I guess running lxc with ns subsystem of cgroup has still problems.

OK, I've confirmed my expectation is correct. With 0.8.0, I can get
proper used memory value without ns subsystem and cannot with
ns enabled.

The reason why this happens is as follows: ns creates a subgroup
on every fork and put any child processes into them. So all processes
in a container place under sub directories of libvirt/lxc/<domain>/.
OTOH, cgroup.memory subsystem accounts memory statistics only
its group by default, i.e., it isn't aware of sub groups (directories).
On issuing dominfo, lxc driver just gets memory statistics of
libvirt/lxc/<domain>/ that has no process, eventually we always get 0
as used memory.

I think one solution that addresses this problem is to enable
memory.use_hierarchy for every creation of libvirt/lxc/<domain>/.
The option allows to account memory statistics with hierarchal
manner and we can get total memory consumptions at the top
of groups, i.e., libvirt/lxc/<domain>/.

Thanks,
  ozaki-r


>
>  ozaki-r
>
>
>>
>> Regards,
>> Srikanth.
>>
>> -----Original Message-----
>> From: Ryota Ozaki [mailto:ozaki ryota gmail com]
>> Sent: Thursday, April 29, 2010 6:14 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 9:32 PM, Kumar L Srikanth-B22348 <B22348 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 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 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 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 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 redhat com]
>>>>> Sent: Wednesday, April 28, 2010 4:46 PM
>>>>> To: Kumar L Srikanth-B22348
>>>>> Cc: libvir-list 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
>>>>> --
>>>>> |: Red Hat, Engineering, London    -o-
>>>>> http://people.redhat.com/berrange/ :|
>>>>> |: http://libvirt.org -o- http://virt-manager.org -o-
>>>>> http://deltacloud.org :|
>>>>> |: http://autobuild.org        -o-
>>>>> http://search.cpan.org/~danberr/ :|
>>>>> |: GnuPG: 7D3B9505  -o-   F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742
>>>>> |7D3B
>>>>> 9505 :|
>>>>>
>>>>>
>>>>> --
>>>>> libvir-list mailing list
>>>>> libvir-list redhat com
>>>>> https://www.redhat.com/mailman/listinfo/libvir-list
>>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>


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