[libvirt] getFreeMemory reporting incorrectly?

[Hany Fahim]

Hey Daniel,
I just patched the source and compiled. It properly reports the free memory
now:

[root at 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())
134217728

Thanks for all your help!

Hany

On Fri, Jun 12, 2009 at 10:44 AM, Daniel P. Berrange <berrange at redhat.com>wrote:

> On Thu, Jun 11, 2009 at 02:37:57PM -0400, Hany Fahim wrote:
> > Thanks Daniel,
> > Is it fair to assume this fix may appear in the next release of libvirt?
>
> If you want to build from source, I'd appreciate feedback on whether
> the following patch fixes the problem
>
> diff -r f204769dd197 src/xen_internal.c
> --- a/src/xen_internal.c        Wed Jun 03 13:52:06 2009 +0000
> +++ b/src/xen_internal.c        Fri Jun 12 15:44:05 2009 +0100
> @@ -241,6 +241,15 @@ struct xen_v2s4_availheap {
>
>  typedef struct xen_v2s4_availheap  xen_v2s4_availheap;
>
> +struct xen_v2s5_availheap {
> +    uint32_t min_bitwidth;  /* Smallest address width (zero if don't
> care). */
> +    uint32_t max_bitwidth;  /* Largest address width (zero if don't care).
> */
> +    int32_t  node;          /* NUMA node (-1 for sum across all nodes). */
> +    uint64_t avail_bytes ALIGN_64;   /* Bytes available in the specified
> region. */
> +};
> +
> +typedef struct xen_v2s5_availheap  xen_v2s5_availheap;
> +
>
>  #define XEN_GETDOMAININFOLIST_ALLOC(domlist, size)                      \
>     (hypervisor_version < 2 ?                                           \
> @@ -650,6 +659,7 @@ struct xen_op_v2_sys {
>         xen_v2s3_getdomaininfolistop getdomaininfolists3;
>         xen_v2_getschedulerid        getschedulerid;
>         xen_v2s4_availheap           availheap;
> +        xen_v2s5_availheap           availheap5;
>         uint8_t padding[128];
>     } u;
>  };
> @@ -3125,12 +3135,18 @@ xenHypervisorNodeGetCellsFreeMemory(virC
>     op_sys.cmd = XEN_V2_OP_GETAVAILHEAP;
>
>     for (i = startCell, j = 0;(i < priv->nbNodeCells) && (j <
> maxCells);i++,j++) {
> -        op_sys.u.availheap.node = i;
> +        if (sys_interface_version >= 5)
> +            op_sys.u.availheap5.node = i;
> +        else
> +            op_sys.u.availheap.node = i;
>         ret = xenHypervisorDoV2Sys(priv->handle, &op_sys);
>         if (ret < 0) {
>             return(-1);
>         }
> -        freeMems[j] = op_sys.u.availheap.avail_bytes;
> +        if (sys_interface_version >= 5)
> +            freeMems[j] = op_sys.u.availheap5.avail_bytes;
> +        else
> +            freeMems[j] = op_sys.u.availheap.avail_bytes;
>     }
>     return (j);
>  }
>
>
>
> > >
> > >
> > > This shows that the Hypervisor  is giving correct info back with both
> > > versions. So the problem must be at the libvirt space, and I believe
> > > I know what the problem is.
> > >
> > > The version of Xen in RHEL5 has
> > >
> > > struct xen_sysctl_availheap {
> > >    /* IN variables. */
> > >    uint32_t min_bitwidth;  /* Smallest address width (zero if don't
> care).
> > > */
> > >    uint32_t max_bitwidth;  /* Largest address width (zero if don't
> care).
> > > */
> > >    int32_t  node;          /* NUMA node of interest (-1 for all nodes).
> */
> > >    /* OUT variables. */
> > >    uint64_t avail_bytes;   /* Bytes available in the specified region.
> */
> > > };
> > >
> > > While upstream Xen has
> > >
> > > struct xen_sysctl_availheap {
> > >    /* IN variables. */
> > >    uint32_t min_bitwidth;  /* Smallest address width (zero if don't
> care).
> > > */
> > >    uint32_t max_bitwidth;  /* Largest address width (zero if don't
> care).
> > > */
> > >    int32_t  node;          /* NUMA node of interest (-1 for all nodes).
> */
> > >    /* OUT variables. */
> > >    uint64_aligned_t avail_bytes;/* Bytes available in the specified
> region.
> > > */
> > > };
> > >
> > > Notice the 'avail_bytes' field is now aligned, so its 4 bytes further
> > > down from where libvirt is expecting it to be.
> > >
> > > We'll have to provide a fix in libvirt to use the new alignment for
> > > newer Xen.
>
> Daniel
> --
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> :|
>
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