Re: [libvirt] [PATCH] nodeinfo: Add workaround if kernel reports bogous numa topology.

This patch adds a workaround for the cpu topology detection code if the kernel reports incorrect count of numa nodes or any other reason that might result in duplicate core ID's in one socket.

If such a situation is detected, the detection code reports the correct number of processors but the topology is mangled: $ virsh nodeinfo CPU model: x86_64 CPU(s): 24 CPU frequency: 2200 MHz CPU socket(s): 1 Core(s) per socket: 24 Thread(s) per core: 1 NUMA cell(s): 1 Memory size: 8047272 KiB This patch also adds test data for such a situation. Reported (and test data provided) by: gcbirzan on #virt@OFTC --- This patch looks huge but it's mostly test data.

+++ b/src/nodeinfo.c @@ -200,7 +200,9 @@ CPU_COUNT(cpu_set_t *set) # endif /* !CPU_COUNT */ /* parses a node entry, returning number of processors in the node and - * filling arguments */ + * filling arguments. + * Returns -1 on error, -2 if kernel reports invalid numa topology and number + * of processors in the node otherwise */ static int virNodeParseNode(const char *node, int *sockets, int *cores, int *threads) ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) @@ -219,6 +221,7 @@ virNodeParseNode(const char *node, int *sockets, int *cores, int *threads) int siblings; unsigned int cpu; int online; + bool bad_topology = false; *threads = 0; *cores = 0; @@ -300,11 +303,14 @@ virNodeParseNode(const char *node, int *sockets, int *cores, int *threads) core = virNodeGetCpuValue(node, cpu, "topology/core_id", false); # endif - CPU_SET(core, &core_maps[sock]); - if (!(siblings = virNodeCountThreadSiblings(node, cpu))) goto cleanup; + if (CPU_ISSET(core, &core_maps[sock]) && siblings <= 1) + bad_topology = true; + + CPU_SET(core, &core_maps[sock]);