[libvirt] [PATCH] conf: Check for NUMA distances in validity check

[Michal Privoznik]

On 02/06/2018 09:34 PM, Peter Krempa wrote:
> On Tue, Feb 06, 2018 at 17:23:47 +0100, Michal Privoznik wrote:
>> NUMA distances are part of guest ABI (guests can read it
>> directly!) and therefore as such shouldn't change throughout the
>> lifetime of domain.
>>
>> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
>> ---
>>  src/conf/numa_conf.c | 13 ++++++++++++-
>>  1 file changed, 12 insertions(+), 1 deletion(-)
>>
>> diff --git a/src/conf/numa_conf.c b/src/conf/numa_conf.c
>> index c906a53de..7d3f9e661 100644
>> --- a/src/conf/numa_conf.c
>> +++ b/src/conf/numa_conf.c
>> @@ -1073,7 +1073,7 @@ bool
>>  virDomainNumaCheckABIStability(virDomainNumaPtr src,
>>                                 virDomainNumaPtr tgt)
>>  {
>> -    size_t i;
>> +    size_t i, j;
> 
> Please declare j on a separate line.

Okay.

> 
>>      if (virDomainNumaGetNodeCount(src) != virDomainNumaGetNodeCount(tgt)) {
>>          virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
>> @@ -1102,6 +1102,17 @@ virDomainNumaCheckABIStability(virDomainNumaPtr src,
>>                               "match source"), i);
>>              return false;
>>          }
>> +
>> +        for (j = 0; j < virDomainNumaGetNodeCount(src); j++) {
> 
> Since the matrix of distances is symetrical along the diagonal, do we
> really need to check both parts? As in .. how about initializing 'j' to
> 'i' in this loop?
> 

Is it symmetrical? Does it have to be? I mean, I've never seen
asymmetrical NUMA machine but I don't usually bother checking distance
matrix when I'm on a NUMA machine (very rarely actually).

Michal