perf: add cpu_migrations software perf event support

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

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

docs/formatdomain.html.in

@@ -1951,6 +1951,7 @@
   <event name='task_clock' enabled='no'/>
   <event name='page_faults' enabled='no'/>
   <event name='context_switches' enabled='no'/>
+  <event name='cpu_migrations' enabled='no'/>
 </perf>
 ...
 </pre>
@@ -2056,6 +2057,13 @@
           the platform</td>
       <td><code>perf.context_switches</code></td>
     </tr>
+    <tr>
+      <td><code>cpu_migrations</code></td>
+      <td>the count of cpu migrations, that is, where the process
+          moved from one logical processor to another, by
+          applications running on the platform</td>
+      <td><code>perf.cpu_migrations</code></td>
+    </tr>
   </table>
 
     <h3><a name="elementsDevices">Devices</a></h3>

docs/schemas/domaincommon.rng

@@ -437,6 +437,7 @@
               <value>task_clock</value>
               <value>page_faults</value>
               <value>context_switches</value>
+              <value>cpu_migrations</value>
             </choice>
           </attribute>
           <attribute name="enabled">

include/libvirt/libvirt-domain.h

@@ -2230,6 +2230,15 @@ void virDomainStatsRecordListFree(virDomainStatsRecordPtr *stats);
  */
 # define VIR_PERF_PARAM_CONTEXT_SWITCHES "context_switches"
 
+/**
+ * VIR_PERF_PARAM_CPU_MIGRATIONS:
+ *
+ * Macro for typed parameter name that represents cpu_migrations
+ * perf event which can be used to measure the count of cpu
+ * migrations by applications running on the platform. It corresponds
+ * to the "perf.cpu_migrations" field in the *Stats APIs.
+ */
+# define VIR_PERF_PARAM_CPU_MIGRATIONS "cpu_migrations"
 
 int virDomainGetPerfEvents(virDomainPtr dom,
                            virTypedParameterPtr *params,

src/libvirt-domain.c

@@ -11259,6 +11259,10 @@ virConnectGetDomainCapabilities(virConnectPtr conn,
  *     "perf.context_switches" - The count of context switches as unsigned long
  *                               long. It is produced by the context_switches
  *                               perf event.
+ *     "perf.cpu_migrations" - The count of cpu migrations, from one logical
+ *                             processor to another, as unsigned long
+ *                             long. It is produced by the cpu_migrations
+ *                             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

@@ -9571,6 +9571,7 @@ qemuDomainSetPerfEvents(virDomainPtr dom,
                                VIR_PERF_PARAM_TASK_CLOCK, VIR_TYPED_PARAM_BOOLEAN,
                                VIR_PERF_PARAM_PAGE_FAULTS, VIR_TYPED_PARAM_BOOLEAN,
                                VIR_PERF_PARAM_CONTEXT_SWITCHES, VIR_TYPED_PARAM_BOOLEAN,
+                               VIR_PERF_PARAM_CPU_MIGRATIONS, VIR_TYPED_PARAM_BOOLEAN,
                                NULL) < 0)
         return -1;
 

src/util/virperf.c

@@ -45,7 +45,7 @@ VIR_ENUM_IMPL(virPerfEvent, VIR_PERF_EVENT_LAST,
               "bus_cycles", "stalled_cycles_frontend",
               "stalled_cycles_backend", "ref_cpu_cycles",
               "cpu_clock", "task_clock", "page_faults",
-              "context_switches");
+              "context_switches", "cpu_migrations");
 
 struct virPerfEvent {
     int type;
@@ -126,6 +126,9 @@ static struct virPerfEventAttr attrs[] = {
     {.type = VIR_PERF_EVENT_CONTEXT_SWITCHES,
      .attrType = PERF_TYPE_SOFTWARE,
      .attrConfig = PERF_COUNT_SW_CONTEXT_SWITCHES},
+    {.type = VIR_PERF_EVENT_CPU_MIGRATIONS,
+     .attrType = PERF_TYPE_SOFTWARE,
+     .attrConfig = PERF_COUNT_SW_CPU_MIGRATIONS},
 };
 typedef struct virPerfEventAttr *virPerfEventAttrPtr;
 

src/util/virperf.h

@@ -51,6 +51,7 @@ typedef enum {
     VIR_PERF_EVENT_TASK_CLOCK,   /* Count of task clock time*/
     VIR_PERF_EVENT_PAGE_FAULTS,   /* Count of total page faults */
     VIR_PERF_EVENT_CONTEXT_SWITCHES,   /* Count of context switches */
+    VIR_PERF_EVENT_CPU_MIGRATIONS,   /* Count of cpu migrations */
 
     VIR_PERF_EVENT_LAST
 } virPerfEventType;

tests/genericxml2xmlindata/generic-perf.xml

@@ -30,6 +30,7 @@
     <event name='task_clock' enabled='yes'/>
     <event name='page_faults' enabled='yes'/>
     <event name='context_switches' enabled='yes'/>
+    <event name='cpu_migrations' enabled='yes'/>
   </perf>
   <devices>
   </devices>

tools/virsh.pod

@@ -968,6 +968,7 @@ I<--perf> returns the statistics of all enabled perf events:
  "perf.task_clock" - the count of task clock time
  "perf.page_faults" - the count of page faults
  "perf.context_switches" - the count of context switches
+ "perf.cpu_migrations" - the count of cpu migrations
 
 See the B<perf> command for more details about each event.
 
@@ -2345,6 +2346,8 @@ B<Valid perf event names>
                 applications running on the platform.
   context_switches - Provides the count of context switches
                      by applications running on the platform.
+  cpu_migrations - Provides the count cpu migrations by
+                   applications running on the platform.
 
 B<Note>: The statistics can be retrieved using the B<domstats> command using
 the I<--perf> flag.