src: warn against virNodeGetInfo() API call due to inaccurate info

Reviewed-by: NJiri Denemark <jdenemar@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

include/libvirt/libvirt-host.h

@@ -147,6 +147,10 @@ typedef virSecurityModel *virSecurityModelPtr;
  *
  * a virNodeInfo is a structure filled by virNodeGetInfo() and providing
  * the information for the Node.
+ *
+ * Note that the information in this struct is not guaranteed to be an
+ * accurate relection of the system hardware. See the virNodeGetInfo()
+ * API documentation for further guidance.
  */
 
 typedef struct _virNodeInfo virNodeInfo;

src/libvirt-host.c

@@ -399,6 +399,22 @@ virConnectGetMaxVcpus(virConnectPtr conn,
  *
  * Extract hardware information about the node.
  *
+ * Use of this API is strongly discouraged as the information provided
+ * is not guaranteed to be accurate on all hardware platforms.
+ *
+ * The mHZ value merely reflects the speed that the first CPU in the
+ * machine is currently running at. This speed may vary across CPUs
+ * and changes continually as the host OS throttles.
+ *
+ * The nodes/sockets/cores/threads data is potentially inaccurate as
+ * it assumes a symmetric installation. If one NUMA node has more
+ * sockets populated that another NUMA node this information will be
+ * wrong. It is also not able to report about CPU dies.
+ *
+ * Applications are recommended to use the virConnectGetCapabilities()
+ * call instead, which provides all the information except CPU mHZ,
+ * in a more accurate representation.
+ *
  * Returns 0 in case of success and -1 in case of failure.
  */
 int