7:15 a.m.
Hi,
It appears to be no API available to provide the memory used by a guest
domin.
I looked at the availble libvirt api called "virNodeGetCellsFreeMemory"
using which it is possible to get the free mem. But looking further I found
that this is free memory of the "whole box" rather than based upon the guest
domain.
How can I get the memory used by a guest domin.
Thanks n Regards,
-Pranay.
7:18 a.m.
On Wed, Apr 30, 2008 at 05:45:55PM +0530, Pranay Prasoon wrote:
Hi,
It appears to be no API available to provide the memory used by a guest
domin.
I looked at the availble libvirt api called "virNodeGetCellsFreeMemory"
using which it is possible to get the free mem. But looking further I found
that this is free memory of the "whole box" rather than based upon the guest
domain.
How can I get the memory used by a guest domin.
virDomainGetInfo()
It fills in a virDomainInfo struct with
unsigned long maxMem; /* the maximum memory in KBytes allowed */
unsigned long memory; /* the memory in KBytes used by the domain */
Dan.
--
|: Red Hat, Engineering, Boston -o- http://people.redhat.com/berrange/ :|
|: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.org :|
|: http://autobuild.org -o- http://search.cpan.org/~danberr/ :|
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8:07 a.m.
Hi dan,
I got confused with your answer, virDomainInfo memory,
Does it mean that all allocated memory is utilized by the guest OS?
Their is good chance that Guest OS may not be utilizing all memory.
How to find out the Currently running Guest Domains memory utilization
level?
On Wed, 2008-04-30 at 13:18 +0100, Daniel P. Berrange wrote:y
On Wed, Apr 30, 2008 at 05:45:55PM +0530, Pranay Prasoon wrote:
> Hi,
> It appears to be no API available to provide the memory used by a guest
> domin.
> I looked at the availble libvirt api called "virNodeGetCellsFreeMemory"
> using which it is possible to get the free mem. But looking further I found
> that this is free memory of the "whole box" rather than based upon the
guest
> domain.
> How can I get the memory used by a guest domin.
virDomainGetInfo()
It fills in a virDomainInfo struct with
unsigned long maxMem; /* the maximum memory in KBytes allowed */
unsigned long memory; /* the memory in KBytes used by the domain */
Dan.
Thanks & Regards
--Ajish
7:57 a.m.
On Wed, Apr 30, 2008 at 06:37:26PM +0530, ajishrao wrote:
Hi dan,
I got confused with your answer, virDomainInfo memory,
Does it mean that all allocated memory is utilized by the guest OS?
No, this just tells you how much memory the hypervisor has allocated
to the guest OS.
Their is good chance that Guest OS may not be utilizing all memory.
Correct. The only way to find that out is to ask the guest OS for its
fine grained breakdown of memory usage. The hypervisor/host OS doesn't
have ability to get this information.
How to find out the Currently running Guest Domains memory
utilization
level?
You'll want to have some monitoring agent inside your guest OS. One example
lightweight agent is 'collected'. It'll transmit utilization data to any
host over the network where you can analyse it
Dan.
--
|: Red Hat, Engineering, Boston -o- http://people.redhat.com/berrange/ :|
|: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.org :|
|: http://autobuild.org -o- http://search.cpan.org/~danberr/ :|
|: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|
6:27 a.m.
New subject: [libvirt] Re: [Libvir] How to get the memory used by a guest domin
On Wed, Apr 30, 2008 at 01:57:21PM +0100, Daniel P. Berrange wrote:
You'll want to have some monitoring agent inside your guest OS.
One example
lightweight agent is 'collected'. It'll transmit utilization data to any
Dan means collectd, from http://collectd.org/
I'll emphasize what Dan said: The only way to reliably get things like
real memory usage, process lists and so on from the guest is to run
some agent/program inside the guest. This is how VMWare does it.
I've been chipping away at these restrictions, because I think it'd be
useful for sysadmins to be able to see guest status from the dom0
without needing to install software in the guests. For disk usage, we
now have virt-df (http://et.redhat.com/~rjones/virt-df/) which runs
entirely in the dom0. Virt-df works by parsing the guest's disk image
-- a hard but tractable problem that turns out to give pretty reliable
results in most scenarios.
However for getting guest memory / process lists the situation is much
more complicated. You'd need to peek into the guest's memory and read
kernel structures, a very complex problem indeed (and not even
tractable on a certain popular closed-source operating system).
A more tractable alternative is to run an agent in the guest which is
common and widely available, such as a simple kernel module that
shares data over a common host <-> guest bus. It would be kind of
like virtio [http://lwn.net/Articles/239238/] for monitoring.
Rich.
--
Richard Jones, Emerging Technologies, Red Hat http://et.redhat.com/~rjones
virt-p2v converts physical machines to virtual machines. Boot with a
live CD or over the network (PXE) and turn machines into Xen guests.
http://et.redhat.com/~rjones/virt-p2v
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4 comments
4 participants
participants (4)
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ajishrao -
Daniel P. Berrange -
Pranay Prasoon -
Richard W.M. Jones