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Re: [libvirt] [PATCH] Make nodeGetInfo report the correct number of NUMA nodes.



On 03/12/2010 06:32 AM, Daniel Veillard wrote:
> On Thu, Mar 11, 2010 at 06:00:56PM -0500, Chris Lalancette wrote:
>> The nodeGetInfo code was always assuming that machine had a
>> single NUMA node, which is not correct.  The good news is that
>> libnuma gives us this information pretty easily, so let's
>> properly report it.
> 
>   okay
> 
>> NOTE: With recent hardware starting to support CPU hot-add
>> and hot-remove, both this code and the nodeCapsInitNUMA()
>> code are quickly going to become obsolete.  We'll have to
>> think of a more dynamic solution for dealing with NUMA
>> nodes and CPUs that can come and go at will.
> 
>   well it makes little sense to refresh all the time,
> I would expect some kind of signal we can hook on to detect
> change in topology or capacities, though I don't see anything
> on signal.h for this

Well, it's actually not horrible to refresh all of the time.  The
way we get this information is all in memory (from /proc or /sys),
so it's a very fast operation.  That being said, if we can get
a signal when things change, and just react to that, that's probably
the best way to go.  This stuff is all very new, so things are
still being put into place; we'll just have to figure out how to
be more dynamic in the future.

> 
>> Signed-off-by: Chris Lalancette <clalance redhat com>
>> ---
>>  src/nodeinfo.c |    6 +++++-
>>  1 files changed, 5 insertions(+), 1 deletions(-)
>>
>> diff --git a/src/nodeinfo.c b/src/nodeinfo.c
>> index 0748602..8d7e055 100644
>> --- a/src/nodeinfo.c
>> +++ b/src/nodeinfo.c
>> @@ -159,7 +159,11 @@ int linuxNodeInfoCPUPopulate(virConnectPtr conn, FILE *cpuinfo,
>>  
>>      nodeinfo->cpus = 0;
>>      nodeinfo->mhz = 0;
>> -    nodeinfo->nodes = nodeinfo->cores = 1;
>> +    nodeinfo->cores = 1;
>> +    if (numa_available() < 0)
>> +        nodeinfo->nodes = 1;
>> +    else
>> +        nodeinfo->nodes = numa_max_node() + 1;
>>  
>>      /* NB: It is impossible to fill our nodes, since cpuinfo
>>       * has no knowledge of NUMA nodes */
> 
>   ACK,

Thanks, I've pushed this now.

-- 
Chris Lalancette


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