Replace sysctl.physinfo.sockets_per_node with more directly useful

sysctl.physinfo.nr_cpus. This also avoids miscalculation of
sockets_per_node by Xen where the number of CPUs in the system is
clipped.
From: Elizabeth Kon <eak@us.ibm.com>
Signed-off-by: Keir Fraser <keir@xensource.com>

tools/python/xen/lowlevel/xc/xc.c

@@ -801,7 +801,7 @@ static PyObject *pyxc_physinfo(XcObject *self)
                             "max_cpu_id",       info.max_cpu_id,
                             "threads_per_core", info.threads_per_core,
                             "cores_per_socket", info.cores_per_socket,
-                            "sockets_per_node", info.sockets_per_node,
+                            "nr_cpus",          info.nr_cpus, 
                             "total_memory",     pages_to_kib(info.total_pages),
                             "free_memory",      pages_to_kib(info.free_pages),
                             "scrub_memory",     pages_to_kib(info.scrub_pages),

tools/python/xen/xend/XendNode.py

@@ -475,7 +475,7 @@ class XendNode:
 
         cpu_info = {
             "nr_nodes":         phys_info["nr_nodes"],
-            "sockets_per_node": phys_info["sockets_per_node"],
+            "nr_cpus":          phys_info["nr_cpus"],
             "cores_per_socket": phys_info["cores_per_socket"],
             "threads_per_core": phys_info["threads_per_core"]
             }
@@ -580,17 +580,9 @@ class XendNode:
             str='none\n'
         return str[:-1];
 
-    def count_cpus(self, pinfo):
-        count=0
-        node_to_cpu=pinfo['node_to_cpu']
-        for i in range(0, pinfo['nr_nodes']):
-            count+=len(node_to_cpu[i])
-        return count;
-
     def physinfo(self):
         info = self.xc.physinfo()
 
-        info['nr_cpus'] = self.count_cpus(info)
         info['cpu_mhz'] = info['cpu_khz'] / 1000
         
         # physinfo is in KiB, need it in MiB
@@ -600,7 +592,6 @@ class XendNode:
 
         ITEM_ORDER = ['nr_cpus',
                       'nr_nodes',
-                      'sockets_per_node',
                       'cores_per_socket',
                       'threads_per_core',
                       'cpu_mhz',

tools/python/xen/xm/main.py

@@ -1667,9 +1667,8 @@ def xm_info(args):
             "release":           getVal(["software_version", "release"]),
             "version":           getVal(["software_version", "version"]),
             "machine":           getVal(["software_version", "machine"]),
-            "nr_cpus":           len(getVal(["host_CPUs"], [])),
+            "nr_cpus":           getVal(["cpu_configuration", "nr_cpus"]),
             "nr_nodes":          getVal(["cpu_configuration", "nr_nodes"]),
-            "sockets_per_node":  getVal(["cpu_configuration", "sockets_per_node"]),
             "cores_per_socket":  getVal(["cpu_configuration", "cores_per_socket"]),
             "threads_per_core":  getVal(["cpu_configuration", "threads_per_core"]),
             "cpu_mhz":           getCpuMhz(),