perf: add ref_cpu_cycles perf event support

This patch adds support and documentation for
the ref_cpu_cycles perf event.
Signed-off-by: NNitesh Konkar <nitkon12@linux.vnet.ibm.com>

docs/formatdomain.html.in

@@ -1932,6 +1932,7 @@
   <event name='bus_cycles' enabled='no'/>
   <event name='stalled_cycles_frontend' enabled='no'/>
   <event name='stalled_cycles_backend' enabled='no'/>
+  <event name='ref_cpu_cycles' enabled='no'/>
 </perf>
 ...
 </pre>
@@ -2004,6 +2005,12 @@
           processor pipeline by applications running on the platform</td>
       <td><code>perf.stalled_cycles_backend</code></td>
     </tr>
+    <tr>
+      <td><code>ref_cpu_cycles</code></td>
+      <td>the count of total cpu cycles not affected by CPU frequency scaling
+         by applications running on the platform</td>
+      <td><code>perf.ref_cpu_cycles</code></td>
+    </tr>
   </table>
 
     <h3><a name="elementsDevices">Devices</a></h3>

docs/news.html.in

@@ -37,8 +37,8 @@
           <li>perf: Add more perf statistics<br/>
           Add support to get the count of branch instructions
           executed, branch misses, bus cycles, stalled frontend
-          cpu cycles, and stalled backend cpu cycles by applications
-          running on the platform
+          cpu cycles, stalled backend cpu cycles, and ref cpu
+          cycles by applications running on the platform
           </li>
         </ul>
       </li>

docs/schemas/domaincommon.rng

@@ -432,6 +432,7 @@
               <value>bus_cycles</value>
               <value>stalled_cycles_frontend</value>
               <value>stalled_cycles_backend</value>
+              <value>ref_cpu_cycles</value>
             </choice>
           </attribute>
           <attribute name="enabled">

include/libvirt/libvirt-domain.h

@@ -2177,6 +2177,17 @@ void virDomainStatsRecordListFree(virDomainStatsRecordPtr *stats);
  */
 # define VIR_PERF_PARAM_STALLED_CYCLES_BACKEND "stalled_cycles_backend"
 
+/**
+ * VIR_PERF_PARAM_REF_CPU_CYCLES:
+ *
+ * Macro for typed parameter name that represents ref_cpu_cycles
+ * perf event which can be used to measure the count of total cpu
+ * cycles not affected by CPU frequency scaling by applications
+ * running on the platform. It corresponds to the
+ * "perf.ref_cpu_cycles" field in the *Stats APIs.
+ */
+# define VIR_PERF_PARAM_REF_CPU_CYCLES "ref_cpu_cycles"
+
 int virDomainGetPerfEvents(virDomainPtr dom,
                            virTypedParameterPtr *params,
                            int *nparams,

src/libvirt-domain.c

@@ -11246,6 +11246,10 @@ virConnectGetDomainCapabilities(virConnectPtr conn,
  *                                      pipeline as unsigned long long. It is
  *                                      produced by stalled_cycles_backend
  *                                      perf event.
+ *     "perf.ref_cpu_cycles" - The count of total cpu cycles not affected by
+ *                             CPU frequency scaling by applications running
+ *                             as unsigned long long. It is produced by the
+ *                             ref_cpu_cycles perf event.
  *
  * Note that entire stats groups or individual stat fields may be missing from
  * the output in case they are not supported by the given hypervisor, are not

src/qemu/qemu_driver.c

@@ -9858,6 +9858,7 @@ qemuDomainSetPerfEvents(virDomainPtr dom,
                                VIR_PERF_PARAM_BUS_CYCLES, VIR_TYPED_PARAM_BOOLEAN,
                                VIR_PERF_PARAM_STALLED_CYCLES_FRONTEND, VIR_TYPED_PARAM_BOOLEAN,
                                VIR_PERF_PARAM_STALLED_CYCLES_BACKEND, VIR_TYPED_PARAM_BOOLEAN,
+                               VIR_PERF_PARAM_REF_CPU_CYCLES, VIR_TYPED_PARAM_BOOLEAN,
                                NULL) < 0)
         return -1;
 

src/util/virperf.c

@@ -43,7 +43,7 @@ VIR_ENUM_IMPL(virPerfEvent, VIR_PERF_EVENT_LAST,
               "cache_references", "cache_misses",
               "branch_instructions", "branch_misses",
               "bus_cycles", "stalled_cycles_frontend",
-              "stalled_cycles_backend");
+              "stalled_cycles_backend", "ref_cpu_cycles");
 
 struct virPerfEvent {
     int type;
@@ -103,6 +103,9 @@ static struct virPerfEventAttr attrs[] = {
     {.type = VIR_PERF_EVENT_STALLED_CYCLES_BACKEND,
      .attrType = PERF_TYPE_HARDWARE,
      .attrConfig = PERF_COUNT_HW_STALLED_CYCLES_BACKEND},
+    {.type = VIR_PERF_EVENT_REF_CPU_CYCLES,
+     .attrType = PERF_TYPE_HARDWARE,
+     .attrConfig = PERF_COUNT_HW_REF_CPU_CYCLES},
 };
 typedef struct virPerfEventAttr *virPerfEventAttrPtr;
 

src/util/virperf.h

@@ -46,6 +46,7 @@ typedef enum {
     VIR_PERF_EVENT_STALLED_CYCLES_BACKEND, /* Count of stalled cpu cycles in
                                               the backend of the instruction
                                               processor pipeline */
+    VIR_PERF_EVENT_REF_CPU_CYCLES,   /* Count of ref cpu cycles */
 
     VIR_PERF_EVENT_LAST
 } virPerfEventType;

tests/genericxml2xmlindata/generic-perf.xml

@@ -25,6 +25,7 @@
     <event name='bus_cycles' enabled='yes'/>
     <event name='stalled_cycles_frontend' enabled='yes'/>
     <event name='stalled_cycles_backend' enabled='yes'/>
+    <event name='ref_cpu_cycles' enabled='yes'/>
   </perf>
   <devices>
   </devices>

tools/virsh.pod

@@ -950,7 +950,8 @@ I<--perf> returns the statistics of all enabled perf events:
 "perf.branch_misses" - the count of branch misses,
 "perf.bus_cycles" - the count of bus cycles,
 "perf.stalled_cycles_frontend" - the count of stalled frontend cpu cycles,
-"perf.stalled_cycles_backend" - the count of stalled backend cpu cycles
+"perf.stalled_cycles_backend" - the count of stalled backend cpu cycles,
+"perf.ref_cpu_cycles" - the count of ref cpu cycles
 
 See the B<perf> command for more details about each event.
 
@@ -2312,6 +2313,9 @@ B<Valid perf event names>
                            cycles in the backend of the
                            instruction processor pipeline by
                            applications running on the platform.
+  ref_cpu_cycles   -  Provides the count of total cpu cycles
+                      not affected by CPU frequency scaling by
+                      applications running on the platform.
 
 B<Note>: The statistics can be retrieved using the B<domstats> command using
 the I<--perf> flag.