[libvirt] [PATCH] numa: avoid failure in nodememstats on non-NUMA systems

[Boris Fiuczynski]

Looks good to me.

On 09/22/2017 04:12 PM, Viktor Mihajlovski wrote:
> libvirt reports a fake NUMA topology in virConnectGetCapabilities
> even if built without numactl support. The fake NUMA topology consists
> of a single cell representing the host's cpu and memory resources.
> Currently this is the case for ARM and s390[x] RPM builds.
> 
> A client iterating over NUMA cells obtained via virConnectGetCapabilities
> and invoking virNodeGetMemoryStats on them will see an internal failure
> "NUMA isn't available on this host". An example for such a client is
> VDSM.
> 
> Since the intention seems to be that libvirt always reports at least
> a single cell it is necessary to return "fake" node memory statistics
> matching the previously reported fake cell in case NUMA isn't supported
> on the system.
> 
> Signed-off-by: Viktor Mihajlovski <mihajlov at linux.vnet.ibm.com>
> ---
>   src/util/virhostmem.c | 8 ++++++++
>   1 file changed, 8 insertions(+)
> 
> diff --git a/src/util/virhostmem.c b/src/util/virhostmem.c
> index a9ba278..fa04a37 100644
> --- a/src/util/virhostmem.c
> +++ b/src/util/virhostmem.c
> @@ -267,6 +267,14 @@ virHostMemGetStats(int cellNum ATTRIBUTE_UNUSED,
>           FILE *meminfo;
>           int max_node;
> 
> +        /*
> +         * Even if built without numactl, libvirt claims
> +         * to have a one-cells NUMA topology. In such a
> +         * case return the statistics for the entire host.
> +         */
> +        if (!virNumaIsAvailable() && cellNum == 0)
> +            cellNum = VIR_NODE_MEMORY_STATS_ALL_CELLS;
> +
>           if (cellNum == VIR_NODE_MEMORY_STATS_ALL_CELLS) {
>               if (VIR_STRDUP(meminfo_path, MEMINFO_PATH) < 0)
>                   return -1;
> 


-- 
Mit freundlichen Grüßen/Kind regards
    Boris Fiuczynski

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