On Thu, Jul 03, 2014 at 04:31:46PM +0300, Gleb Voronich wrote: > Hello, > > I'm trying to get memory usage statistic inside a guest machine using > virDomainMemoryStats function at libvirt. > According to > http://libvirt.org/html/libvirt-libvirt.html#virDomainMemoryStatTags the > structure could have a lot of useful memory statistic but the amount of > parameters depends on the hypervisor and the driver. > However using KVM I'm able to get VIR_DOMAIN_MEMORY_STAT_ACTUAL_BALLOON > and VIR_DOMAIN_MEMORY_STAT_RSS only. > QEMU/KVM only supports these two IIRC. > Am I right it is not possible to get additional info such as used/unused > memory inside a guest machine in case of KVM? > Yes. Actually reporting some data from *inside* the domain is not what libvirt aims to provide.

> Eric Blake <mailto:eblake@redhat.com> > > > > In the case of the memory balloon device, libvirt CAN provide stats from > > the guest, because of the way the balloon device works. But if you > > aren't using a balloon, or if the guest is not cooperative, this won't > > work. Better would be a guest-agent command for getting at this > > information (but again, you are relying on guest cooperation). In > > short, libvirt is great at stats from the HOST point of view, but for > > stats from the GUEST point of view, you are often better off using the > > same mechanisms that you would for getting stats from a remote bare > > metal machine, without needing libvirt in the mix. > > Thanks Eric. > > 1. I use the balloon for all of my guests: > <memballoon model='virtio'> > But how can I get stats?

> > 2. I've tried the latest QEMU GA 2.0.0

> virDomainMemoryStats() gets those stats, if qemu is new enough to > provide them, and if the guest cooperates to provide them. Well I use the latest QEMU 2.0.0 I have the latest CentOS 6.5 installed on the guest and unfortunately I can't get more stats that I have.

> virDomainMemoryStats() gets those stats, if qemu is new enough to > provide them, and if the guest cooperates to provide them. Well I use the latest QEMU 2.0.0 I have the latest CentOS 6.5 installed on the guest and unfortunately I can't get more stats that I have. > Which OS are you using in your guests? > > Of course, you need to have the virtio balloon driver up and runnig in > your guests. CentOS 6.5 x86_64 It has the balloon driver and it is up and running: # modinfo virtio_balloon filename: /lib/modules/2.6.32-431.17.1.el6.x86_64/kernel/drivers/virtio/virtio_balloon.ko license: GPL description: Virtio balloon driver srcversion: BB9F75B2CAF3435CC507998 alias: virtio:d00000005v* depends: virtio,virtio_ring vermagic: 2.6.32-431.17.1.el6.x86_64 SMP mod_unload modversions

[1 <text/plain; ISO-8859-1 (quoted-printable)>] On 07/04/2014 03:18 PM, Claudio Bley wrote: > At Thu, 03 Jul 2014 17:46:14 +0300, > Gleb Voronich wrote: >> >> >>> virDomainMemoryStats() gets those stats, if qemu is new enough to >>> provide them, and if the guest cooperates to provide them. >> Well I use the latest QEMU 2.0.0 >> I have the latest CentOS 6.5 installed on the guest and unfortunately >> I can't get more stats that I have. >> >>> Which OS are you using in your guests? >>> >>> Of course, you need to have the virtio balloon driver up and runnig in >>> your guests. >> CentOS 6.5 x86_64 >> It has the balloon driver and it is up and running: >> >> # modinfo virtio_balloon >> filename: >> /lib/modules/2.6.32-431.17.1.el6.x86_64/kernel/drivers/virtio/virtio_balloon.ko >> license: GPL >> description: Virtio balloon driver >> srcversion: BB9F75B2CAF3435CC507998 >> alias: virtio:d00000005v* >> depends: virtio,virtio_ring >> vermagic: 2.6.32-431.17.1.el6.x86_64 SMP mod_unload modversions > > In this case, it's your guest kernel that's too old to support these > stats. > > Apparently, reporting statistics in the balloon driver was introduced > in the kernel on 24th Feb 2010 (commit > 9564e138b1f6eb137f7149772438d3f3fb3277dd) which clearly predates > version 2.6.32 (2nd December 2009). Acording to the kernel RPM's changelog, this was backported into 2.6.32-38.el6 and released in RHEL 6.0 (Nov 2010): https://bugzilla.redhat.com/show_bug.cgi?id=601690

> In that case, I'd guess that Gleb just forgot to call > virDomainSetMemoryStatsPeriod, perhaps? I've just performed the same test with CentOS 7 at the host and CentOS 7 at the guest. Everything works. # virsh dommemstat vm1 actual 1048576 swap_in 0 swap_out 0 major_fault 751 minor_fault 3958627 unused 375900 available 1017988 rss 978248 I don't know the reason it doesn't work with ELRepo 3.10.45 kernel but I'd really like to. According to https://bugzilla.redhat.com/show_bug.cgi?id=601690 memoryStats should work at host's side starting from 2.6.32-52.el6 so I suppose the problem is the guest kernel. Do you think this could be caused by an old version of virtio_balloon driver?

Actually, you should get more stats when using the virtio balloon driver in your guests.

At Thu, 03 Jul 2014 17:32:20 +0300, Gleb Voronich wrote: > > >> Actually, you should get more stats when using the virtio balloon >> driver in your guests. > I use the balloon but I can't get more stats. > I use python binding for libvirt and as far as I can see it calls > virDomainMemoryStats exactly. Which OS are you using in your guests? Of course, you need to have the virtio balloon driver up and runnig in your guests.