perf: add page_faults_min software perf event support

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

docs/formatdomain.html.in

@@ -1952,6 +1952,7 @@
   <event name='page_faults' enabled='no'/>
   <event name='context_switches' enabled='no'/>
   <event name='cpu_migrations' enabled='no'/>
+  <event name='page_faults_min' enabled='no'/>
 </perf>
 ...
 </pre>
@@ -2064,6 +2065,14 @@
           applications running on the platform</td>
       <td><code>perf.cpu_migrations</code></td>
     </tr>
+    <tr>
+      <td><code>page_faults_min</code></td>
+      <td>the count of minor page faults, that is, where the
+          page was present in the page cache, and therefore
+          the fault avoided loading it from storage, by
+          applications running on the platform</td>
+      <td><code>perf.page_faults_min</code></td>
+    </tr>
   </table>
 
     <h3><a name="elementsDevices">Devices</a></h3>

docs/schemas/domaincommon.rng

@@ -438,6 +438,7 @@
               <value>page_faults</value>
               <value>context_switches</value>
               <value>cpu_migrations</value>
+              <value>page_faults_min</value>
             </choice>
           </attribute>
           <attribute name="enabled">

include/libvirt/libvirt-domain.h

@@ -2240,6 +2240,16 @@ void virDomainStatsRecordListFree(virDomainStatsRecordPtr *stats);
  */
 # define VIR_PERF_PARAM_CPU_MIGRATIONS "cpu_migrations"
 
+/**
+ * VIR_PERF_PARAM_PAGE_FAULTS_MIN:
+ *
+ * Macro for typed parameter name that represents page_faults_min
+ * perf event which can be used to measure the count of minor page
+ * faults by applications running on the platform. It corresponds
+ * to the "perf.page_faults_min" field in the *Stats APIs.
+ */
+# define VIR_PERF_PARAM_PAGE_FAULTS_MIN  "page_faults_min"
+
 int virDomainGetPerfEvents(virDomainPtr dom,
                            virTypedParameterPtr *params,
                            int *nparams,

src/libvirt-domain.c

@@ -11263,6 +11263,9 @@ virConnectGetDomainCapabilities(virConnectPtr conn,
  *                             processor to another, as unsigned long
  *                             long. It is produced by the cpu_migrations
  *                             perf event.
+ *     "perf.page_faults_min" - The count of minor page faults as unsigned
+ *                              long long. It is produced by the
+ *                              page_faults_min 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

@@ -9572,6 +9572,7 @@ qemuDomainSetPerfEvents(virDomainPtr dom,
                                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,
+                               VIR_PERF_PARAM_PAGE_FAULTS_MIN, VIR_TYPED_PARAM_BOOLEAN,
                                NULL) < 0)
         return -1;
 

src/util/virperf.c

@@ -45,7 +45,8 @@ 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", "cpu_migrations");
+              "context_switches", "cpu_migrations",
+              "page_faults_min");
 
 struct virPerfEvent {
     int type;
@@ -129,6 +130,9 @@ static struct virPerfEventAttr attrs[] = {
     {.type = VIR_PERF_EVENT_CPU_MIGRATIONS,
      .attrType = PERF_TYPE_SOFTWARE,
      .attrConfig = PERF_COUNT_SW_CPU_MIGRATIONS},
+    {.type = VIR_PERF_EVENT_PAGE_FAULTS_MIN,
+     .attrType = PERF_TYPE_SOFTWARE,
+     .attrConfig = PERF_COUNT_SW_PAGE_FAULTS_MIN},
 };
 typedef struct virPerfEventAttr *virPerfEventAttrPtr;
 

src/util/virperf.h

@@ -52,6 +52,7 @@ typedef enum {
     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_PAGE_FAULTS_MIN,   /* Count of minor page faults */
 
     VIR_PERF_EVENT_LAST
 } virPerfEventType;

tests/genericxml2xmlindata/generic-perf.xml

@@ -31,6 +31,7 @@
     <event name='page_faults' enabled='yes'/>
     <event name='context_switches' enabled='yes'/>
     <event name='cpu_migrations' enabled='yes'/>
+    <event name='page_faults_min' enabled='yes'/>
   </perf>
   <devices>
   </devices>

tools/virsh.pod

@@ -969,6 +969,7 @@ I<--perf> returns the statistics of all enabled perf events:
  "perf.page_faults" - the count of page faults
  "perf.context_switches" - the count of context switches
  "perf.cpu_migrations" - the count of cpu migrations
+ "perf.page_faults_min" - the count of minor page faults
 
 See the B<perf> command for more details about each event.
 
@@ -2348,6 +2349,8 @@ B<Valid perf event names>
                      by applications running on the platform.
   cpu_migrations - Provides the count cpu migrations by
                    applications running on the platform.
+  page_faults_min - Provides the count minor page faults
+                    by applications running on the platform.
 
 B<Note>: The statistics can be retrieved using the B<domstats> command using
 the I<--perf> flag.