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

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(a)redhat.com&gt; >> --- >> 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).