perf: add task_clock software perf event support

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

docs/formatdomain.html.in

@@ -1948,6 +1948,7 @@
   <event name='stalled_cycles_backend' enabled='no'/>
   <event name='ref_cpu_cycles' enabled='no'/>
   <event name='cpu_clock' enabled='no'/>
+  <event name='task_clock' enabled='no'/>
 </perf>
 ...
 </pre>
@@ -2033,6 +2034,13 @@
           the platform</td>
       <td><code>perf.cpu_clock</code></td>
     </tr>
+    <tr>
+      <td><code>task_clock</code></td>
+      <td>the count of task clock time, as measured by a monotonic
+          high-resolution CPU timer, specific to the task that
+          is run by applications running on the platform</td>
+      <td><code>perf.task_clock</code></td>
+    </tr>
   </table>
 
     <h3><a name="elementsDevices">Devices</a></h3>

docs/schemas/domaincommon.rng

@@ -434,6 +434,7 @@
               <value>stalled_cycles_backend</value>
               <value>ref_cpu_cycles</value>
               <value>cpu_clock</value>
+              <value>task_clock</value>
             </choice>
           </attribute>
           <attribute name="enabled">

include/libvirt/libvirt-domain.h

@@ -2199,6 +2199,17 @@ void virDomainStatsRecordListFree(virDomainStatsRecordPtr *stats);
  */
 # define VIR_PERF_PARAM_CPU_CLOCK "cpu_clock"
 
+/**
+ * VIR_PERF_PARAM_TASK_CLOCK:
+ *
+ * Macro for typed parameter name that represents task_clock
+ * perf event which can be used to measure the count of task
+ * clock time by applications running on the platform. It
+ * corresponds to the "perf.task_clock" field in the *Stats
+ * APIs.
+ */
+# define VIR_PERF_PARAM_TASK_CLOCK "task_clock"
+
 int virDomainGetPerfEvents(virDomainPtr dom,
                            virTypedParameterPtr *params,
                            int *nparams,

src/libvirt-domain.c

@@ -11252,6 +11252,8 @@ virConnectGetDomainCapabilities(virConnectPtr conn,
  *                             ref_cpu_cycles perf event.
  *     "perf.cpu_clock" - The count of cpu clock time as unsigned long long.
  *                        It is produced by the cpu_clock perf event.
+ *     "perf.task_clock" - The count of task clock time as unsigned long long.
+ *                         It is produced by the task_clock 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

@@ -9568,6 +9568,7 @@ qemuDomainSetPerfEvents(virDomainPtr dom,
                                VIR_PERF_PARAM_STALLED_CYCLES_BACKEND, VIR_TYPED_PARAM_BOOLEAN,
                                VIR_PERF_PARAM_REF_CPU_CYCLES, VIR_TYPED_PARAM_BOOLEAN,
                                VIR_PERF_PARAM_CPU_CLOCK, VIR_TYPED_PARAM_BOOLEAN,
+                               VIR_PERF_PARAM_TASK_CLOCK, VIR_TYPED_PARAM_BOOLEAN,
                                NULL) < 0)
         return -1;
 

src/util/virperf.c

@@ -44,7 +44,7 @@ VIR_ENUM_IMPL(virPerfEvent, VIR_PERF_EVENT_LAST,
               "branch_instructions", "branch_misses",
               "bus_cycles", "stalled_cycles_frontend",
               "stalled_cycles_backend", "ref_cpu_cycles",
-              "cpu_clock");
+              "cpu_clock", "task_clock");
 
 struct virPerfEvent {
     int type;
@@ -116,6 +116,9 @@ static struct virPerfEventAttr attrs[] = {
     {.type = VIR_PERF_EVENT_CPU_CLOCK,
      .attrType = PERF_TYPE_SOFTWARE,
      .attrConfig = PERF_COUNT_SW_CPU_CLOCK},
+    {.type = VIR_PERF_EVENT_TASK_CLOCK,
+     .attrType = PERF_TYPE_SOFTWARE,
+     .attrConfig = PERF_COUNT_SW_TASK_CLOCK},
 };
 typedef struct virPerfEventAttr *virPerfEventAttrPtr;
 

src/util/virperf.h

@@ -48,6 +48,7 @@ typedef enum {
                                               processor pipeline */
     VIR_PERF_EVENT_REF_CPU_CYCLES,   /* Count of ref cpu cycles */
     VIR_PERF_EVENT_CPU_CLOCK,   /* Count of cpu clock time*/
+    VIR_PERF_EVENT_TASK_CLOCK,   /* Count of task clock time*/
 
     VIR_PERF_EVENT_LAST
 } virPerfEventType;

tests/genericxml2xmlindata/generic-perf.xml

@@ -27,6 +27,7 @@
     <event name='stalled_cycles_backend' enabled='yes'/>
     <event name='ref_cpu_cycles' enabled='yes'/>
     <event name='cpu_clock' enabled='yes'/>
+    <event name='task_clock' enabled='yes'/>
   </perf>
   <devices>
   </devices>

tools/virsh.pod

@@ -965,6 +965,7 @@ I<--perf> returns the statistics of all enabled perf events:
                                  cpu cycles
  "perf.ref_cpu_cycles" - the count of ref cpu cycles
  "perf.cpu_clock" - the count of cpu clock time
+ "perf.task_clock" - the count of task clock time
 
 See the B<perf> command for more details about each event.
 
@@ -2336,6 +2337,8 @@ B<Valid perf event names>
                       applications running on the platform.
   cpu_clock - Provides the cpu clock time consumed by
               applications running on the platform.
+  task_clock - Provides the task clock time consumed by
+               applications running on the platform.
 
 B<Note>: The statistics can be retrieved using the B<domstats> command using
 the I<--perf> flag.