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nodeinfo: Add check and workaround to guarantee valid cpu topologies

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Lately there were a few reports of the output of the virsh nodeinfo
command being inaccurate. This patch tries to avoid that by checking if
the topology actually makes sense. If it doesn't we then report a
synthetic topology that indicates to the user that the host capabilities
should be checked for the actual topology.
This commit is contained in:
Peter Krempa 2012-11-07 14:53:36 +01:00
parent fd723164c7
commit 9576afd110
2 changed files with 44 additions and 17 deletions
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8
include/libvirt/libvirt.h.in
View File

@ -539,9 +539,11 @@ struct _virNodeInfo {
topologies or uniform memory access; check
capabilities XML for the actual NUMA topology */
unsigned int sockets; /* number of CPU sockets per node if nodes > 1,
total number of CPU sockets otherwise */
unsigned int cores; /* number of cores per socket */
unsigned int threads;/* number of threads per core */
1 in case of unusual NUMA topology */
unsigned int cores; /* number of cores per socket, total number of
processors in case of unusual NUMA topology*/
unsigned int threads; /* number of threads per core, 1 in case of
unusual numa topology */
};
/**

37
src/nodeinfo.c
View File

@ -204,7 +204,12 @@ CPU_COUNT(cpu_set_t *set)
static int
ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2)
ATTRIBUTE_NONNULL(3) ATTRIBUTE_NONNULL(4)
virNodeParseNode(const char *node, int *sockets, int *cores, int *threads)
ATTRIBUTE_NONNULL(5)
virNodeParseNode(const char *node,
int *sockets,
int *cores,
int *threads,
int *offline)
{
int ret = -1;
int processors = 0;
@ -278,8 +283,10 @@ virNodeParseNode(const char *node, int *sockets, int *cores, int *threads)
if ((online = virNodeGetCpuValue(node, cpu, "online", true)) < 0)
goto cleanup;
if (!online)
if (!online) {
(*offline)++;
continue;
}
processors++;
@ -348,7 +355,7 @@ int linuxNodeInfoCPUPopulate(FILE *cpuinfo,
char line[1024];
DIR *nodedir = NULL;
struct dirent *nodedirent = NULL;
int cpus, cores, socks, threads;
int cpus, cores, socks, threads, offline = 0;
unsigned int node;
int ret = -1;
char *sysfs_nodedir = NULL;
@ -469,8 +476,8 @@ int linuxNodeInfoCPUPopulate(FILE *cpuinfo,
goto cleanup;
}
if ((cpus = virNodeParseNode(sysfs_cpudir, &socks,
&cores, &threads)) < 0)
if ((cpus = virNodeParseNode(sysfs_cpudir, &socks, &cores,
&threads, &offline)) < 0)
goto cleanup;
VIR_FREE(sysfs_cpudir);
@ -505,7 +512,8 @@ fallback:
goto cleanup;
}
if ((cpus = virNodeParseNode(sysfs_cpudir, &socks, &cores, &threads)) < 0)
if ((cpus = virNodeParseNode(sysfs_cpudir, &socks, &cores,
&threads, &offline)) < 0)
goto cleanup;
nodeinfo->nodes = 1;
@ -531,6 +539,23 @@ done:
goto cleanup;
}
/* Now check if the topology makes sense. There are machines that don't
* expose their real number of nodes or for example the AMD Bulldozer
* architecture that exposes their Clustered integer core modules as both
* threads and cores. This approach throws off our detection. Unfortunately
* the nodeinfo structure isn't designed to carry the full topology so
* we're going to lie about the detected topology to notify the user
* to check the host capabilities for the actual topology. */
if ((nodeinfo->nodes *
nodeinfo->sockets *
nodeinfo->cores *
nodeinfo->threads) != (nodeinfo->cpus + offline)) {
nodeinfo->nodes = 1;
nodeinfo->sockets = 1;
nodeinfo->cores = nodeinfo->cpus + offline;
nodeinfo->threads = 1;
}
ret = 0;
cleanup: