perf: add bus_cycles perf event support

This patch adds support and documentation
for the bus_cycles perf event.

Signed-off-by: Nitesh Konkar <nitkon12@linux.vnet.ibm.com>

docs/formatdomain.html.in

@@ -1929,6 +1929,7 @@
   <event name='cache_misses' enabled='no'/>
   <event name='branch_instructions' enabled='no'/>
   <event name='branch_misses' enabled='no'/>
+  <event name='bus_cycles' enabled='no'/>
 </perf>
 ...
 </pre>
@@ -1984,6 +1985,11 @@
       <td>the count of branch misses by applications running on the platform</td>
       <td><code>perf.branch_misses</code></td>
     </tr>
+    <tr>
+      <td><code>bus_cycles</code></td>
+      <td>the count of bus cycles by applications running on the platform</td>
+      <td><code>perf.bus_cycles</code></td>
+    </tr>
   </table>
 
     <h3><a name="elementsDevices">Devices</a></h3>

docs/news.html.in

@@ -35,8 +35,9 @@
       <li><strong>Improvements</strong>
         <ul>
           <li>perf: Add more perf statistics<br/>
-          Add support to get the count of branch instructions executed
-          and branch misses by applications running on the platform
+          Add support to get the count of branch instructions executed,
+          branch misses, and bus cycles by applications running on
+          the platform
           </li>
         </ul>
       </li>

docs/schemas/domaincommon.rng

@@ -429,6 +429,7 @@
               <value>cache_misses</value>
               <value>branch_instructions</value>
               <value>branch_misses</value>
+              <value>bus_cycles</value>
             </choice>
           </attribute>
           <attribute name="enabled">