[Qemu-devel] [question] How to get the guest physical memory usage from host?

[Qemu-devel] [question] How to get the guest physical memory usage from host?

[Zhang Haoyu]

Hi,

How to get the guest physical memory usage from host?
I don't want to introduce a guest-agent to get the info.

Thanks,
Zhang Haoyu

Re: [Qemu-devel] [question] How to get the guest physical memory usage from host?

[Andrey Korolyov]

On Mon, Dec 22, 2014 at 6:59 AM, Zhang Haoyu <zhhy.zhanghaoyu@gmail.com> wrote:
> Hi,
>
> How to get the guest physical memory usage from host?
> I don't want to introduce a guest-agent to get the info.
>
> Thanks,
> Zhang Haoyu
>

There`s probably one approach, simular to (currently abandoned)
virt-dmesg, via peeking to the guest memory directly. What are reasons
for not leaving this task to agent, as it looks much simpler?

Re: [Qemu-devel] [question] How to get the guest physical memory usage from host?

[Zhang Haoyu]

On 2014/12/22 16:41, Andrey Korolyov wrote:
> On Mon, Dec 22, 2014 at 6:59 AM, Zhang Haoyu <zhhy.zhanghaoyu@gmail.com> wrote:
>> Hi,
>>
>> How to get the guest physical memory usage from host?
>> I don't want to introduce a guest-agent to get the info.
>>
>> Thanks,
>> Zhang Haoyu
>>
> 
> There`s probably one approach, simular to (currently abandoned)
> virt-dmesg, via peeking to the guest memory directly. What are reasons
> for not leaving this task to agent, as it looks much simpler?
> 
In some cases, we are not permitted to install anything in customer's guest environment.

Thanks,
Zhang Haoyu

Re: [Qemu-devel] [question] How to get the guest physical memory usage from host?

[Andrey Korolyov]

On Mon, Dec 22, 2014 at 11:57 AM, Zhang Haoyu <zhhy.zhanghaoyu@gmail.com> wrote:
>
> On 2014/12/22 16:41, Andrey Korolyov wrote:
>> On Mon, Dec 22, 2014 at 6:59 AM, Zhang Haoyu <zhhy.zhanghaoyu@gmail.com> wrote:
>>> Hi,
>>>
>>> How to get the guest physical memory usage from host?
>>> I don't want to introduce a guest-agent to get the info.
>>>
>>> Thanks,
>>> Zhang Haoyu
>>>
>>
>> There`s probably one approach, simular to (currently abandoned)
>> virt-dmesg, via peeking to the guest memory directly. What are reasons
>> for not leaving this task to agent, as it looks much simpler?
>>
> In some cases, we are not permitted to install anything in customer's guest environment.
>
> Thanks,
> Zhang Haoyu

Ok, looks like memory peeking techniques are only a choice then. And,
of course, this approach tends to be less flexible, because it depends
on a relatively strict requirements for running kernel in a guest.

Re: [Qemu-devel] [question] How to get the guest physical memory usage from host?

[Zhang Haoyu]

On 2014/12/22 17:16, Andrey Korolyov wrote:
> On Mon, Dec 22, 2014 at 11:57 AM, Zhang Haoyu <zhhy.zhanghaoyu@gmail.com> wrote:
>>
>> On 2014/12/22 16:41, Andrey Korolyov wrote:
>>> On Mon, Dec 22, 2014 at 6:59 AM, Zhang Haoyu <zhhy.zhanghaoyu@gmail.com> wrote:
>>>> Hi,
>>>>
>>>> How to get the guest physical memory usage from host?
>>>> I don't want to introduce a guest-agent to get the info.
>>>>
>>>> Thanks,
>>>> Zhang Haoyu
>>>>
>>>
>>> There`s probably one approach, simular to (currently abandoned)
>>> virt-dmesg, via peeking to the guest memory directly. What are reasons
>>> for not leaving this task to agent, as it looks much simpler?
>>>
>> In some cases, we are not permitted to install anything in customer's guest environment.
>>
>> Thanks,
>> Zhang Haoyu
> 
> Ok, looks like memory peeking techniques are only a choice then. And,
> of course, this approach tends to be less flexible, because it depends
> on a relatively strict requirements for running kernel in a guest.
> 
Yes, it should depends on guest os implementation,
because physical memory is managed by OS, which have the full knowledge of memory usage,
so I'm afraid that windows dose not friendly support it.
Could you detail the peeking techniques mentioned above?

Thanks,
Zhang Haoyu

Re: [Qemu-devel] [question] How to get the guest physical memory usage from host?

[Andrey Korolyov]

> Yes, it should depends on guest os implementation,
> because physical memory is managed by OS, which have the full knowledge of memory usage,
> so I'm afraid that windows dose not friendly support it.
> Could you detail the peeking techniques mentioned above?
>
> Thanks,
> Zhang Haoyu

Generally I meant virDomainMemoryPeek, but nothing prevents you to
write code with same functionality, if libvirt usage is not preferred,
it is only about asking monitor for chunks of memory and parse them in
a proper way.

Re: [Qemu-devel] [question] How to get the guest physical memory usage from host?

[Zhang Haoyu]

On 2014/12/22 17:33, Andrey Korolyov wrote:
>> Yes, it should depends on guest os implementation,
>> because physical memory is managed by OS, which have the full knowledge of memory usage,
>> so I'm afraid that windows dose not friendly support it.
>> Could you detail the peeking techniques mentioned above?
>>
>> Thanks,
>> Zhang Haoyu
> 
> Generally I meant virDomainMemoryPeek, but nothing prevents you to
> write code with same functionality, if libvirt usage is not preferred,
> it is only about asking monitor for chunks of memory and parse them in
> a proper way.
> 
Thanks, Andrey.

Re: [Qemu-devel] [question] How to get the guest physical memory usage from host?

[Richard W.M. Jones]

On Mon, Dec 22, 2014 at 12:41:45PM +0400, Andrey Korolyov wrote:
> On Mon, Dec 22, 2014 at 6:59 AM, Zhang Haoyu <zhhy.zhanghaoyu@gmail.com> wrote:
> > Hi,
> >
> > How to get the guest physical memory usage from host?
> > I don't want to introduce a guest-agent to get the info.
> >
> > Thanks,
> > Zhang Haoyu
> >
> 
> There`s probably one approach, simular to (currently abandoned)
> virt-dmesg, via peeking to the guest memory directly. What are reasons
> for not leaving this task to agent, as it looks much simpler?

Fixing virt-dmesg might be better since it has the machinery already
for talking to libvirt and accessing the guest kernel memory.

Of course there is approx zero chance that this approach will work
for Windows guests.

Rich.

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