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Re: [libvirt] getFreeMemory reporting incorrectly?



Hey Daniel,

Here is the output of 'xm list' from both machines:

Xen 3.0.3 - This machine has 2GB total memory and should report 256MB free:

[root node2 ~]# xm list
Name                                      ID Mem(MiB) VCPUs State   Time(s)
Domain-0                                   0      997     1 r-----  31431.7
test1                                     74      255     1 -b----   2412.4
test2                                     73      511     1 -b----   2434.3


Xen 3.3 - This machine has 3GB total memory and should report 0MB free:

[root node1 ~]# xm list
Name                                        ID   Mem VCPUs      State   Time(s)
Domain-0                                     0  2901     2     r-----    588.5

Both machines are i386 architecture.

Here's the output of the getCellsFreeMemory call:

Xen 3.0.3:

[root node2 ~]# python
Python 2.4.3 (#1, Jan 21 2009, 01:10:13) 
[GCC 4.1.2 20071124 (Red Hat 4.1.2-42)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import libvirt
>>> conn = libvirt.open('xen:///')
>>> print(conn.getCellsFreeMemory(0,10))
[268972032L]

Xen 3.3:

[root node1 ~]# python
Python 2.4.3 (#1, Jan 21 2009, 01:10:13) 
[GCC 4.1.2 20071124 (Red Hat 4.1.2-42)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import libvirt
>>> conn = libvirt.open('xen:///')
>>> print(conn.getCellsFreeMemory(0,10))
[576460752303423488L]

I appreciate the help.

Hany

On Wed, Jun 10, 2009 at 6:24 AM, Daniel P. Berrange <berrange redhat com> wrote:
On Tue, Jun 09, 2009 at 06:00:29PM -0400, Hany Fahim wrote:
> Hi,
> I'm currently running 2 CentOS 5.3 systems, one running Xen 3.3 and libvirt
> 0.6.4 (called node1) and the other running Xen 3.0.3 (stock CentOS) and
> libvirt 0.6.4 (called node2). The machines are practically identical except
> for the upgraded Xen installation. When using the libvirt-python module, I'm
> getting strange values from getFreeMemory() on the Xen 3.3 machine. See
> below:
>
> Xen 3.0.3:
>
> [root node2 ~]# python
> Python 2.4.3 (#1, Jan 21 2009, 01:10:13)
> [GCC 4.1.2 20071124 (Red Hat 4.1.2-42)] on linux2
> Type "help", "copyright", "credits" or "license" for more information.
> >>> import libvirt
> >>> conn = libvirt.open('xen:///')
> >>> print(conn.getFreeMemory())
> 268959744
> >>>
>
> Which is correct since there's approximately 256MB free. Now in the Xen 3.3
> box:
>
> Xen 3.3:
>
> [root node1 ~]# python
> Python 2.4.3 (#1, Jan 21 2009, 01:10:13)
> [GCC 4.1.2 20071124 (Red Hat 4.1.2-42)] on linux2
> Type "help", "copyright", "credits" or "license" for more information.
> >>> import libvirt
> >>> conn = libvirt.open('xen:///')
> >>> print(conn.getFreeMemory())
> 576460752303423488
> >>>
>
> node1 should actually be reporting 0MB free, but instead I'm getting this
> huge number. It would be nice if I had this much memory though... Anybody
> else run into this?

For Xen we get the free memory information from a hypercall. I suspect
that Xen 3.3 has changed the hypercall ABI in some way that is tripping
up libvirt. Can you provide the output of 'xm info' for the 2 machines
you have. Also what architecture are they ?

Also can you check the per-node info with  print(conn.getCellsFreeMemory(0,10))


Daniel
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