Bug 664758 - Add page fault reporting to telemetry. r=taras

--HG--
extra : rebase_source : 89d0936181a705d3d6ec7ceab8648b6694989d20

toolkit/components/telemetry/TelemetryHistograms.h

@@ -37,9 +37,11 @@
  * ***** END LICENSE BLOCK ***** */
 
 /**
- * This file lists Telemetry histograms collected by Firefox.  Format
- *  is HISTOGRAM(id, minium, maximum, bucket count, histogram kind,
- *  human-readable description for about:telemetry)
+ * This file lists Telemetry histograms collected by Firefox.  The format is
+ *
+ *    HISTOGRAM(id, minium, maximum, bucket count, histogram kind,
+ *              human-readable description for about:telemetry)
+ *
  */
 
 HISTOGRAM(CYCLE_COLLECTOR, 1, 10000, 50, EXPONENTIAL, "Time(ms) spent on cycle collection")
@@ -56,5 +58,6 @@ HISTOGRAM(GLUESTARTUP_READ_TRANSFER, 1, 50 * 1024, 12, EXPONENTIAL, "ProcessIoCo
 #elif defined(XP_UNIX)
 HISTOGRAM(EARLY_GLUESTARTUP_HARD_FAULTS, 1, 100, 12, LINEAR, "Hard faults count before glue startup")
 HISTOGRAM(GLUESTARTUP_HARD_FAULTS, 1, 500, 12, EXPONENTIAL, "Hard faults count after glue startup")
+HISTOGRAM(HARD_PAGE_FAULTS, 8, 64 * 1024, 13, EXPONENTIAL, "Hard page faults (since last telemetry ping)")
 #endif
 HISTOGRAM(ZIPARCHIVE_CRC, 0, 1, 2, BOOLEAN, "Zip item CRC check pass")

toolkit/components/telemetry/TelemetryPing.js

@@ -56,7 +56,8 @@ const TELEMETRY_DELAY = 60000;
 const MEM_HISTOGRAMS = {
   "explicit/js/gc-heap": "MEMORY_JS_GC_HEAP",
   "resident": "MEMORY_RESIDENT",
-  "explicit/layout/all": "MEMORY_LAYOUT_ALL"
+  "explicit/layout/all": "MEMORY_LAYOUT_ALL",
+  "hard-page-faults": "HARD_PAGE_FAULTS"
 };
 
 XPCOMUtils.defineLazyGetter(this, "Telemetry", function () {
@@ -184,6 +185,7 @@ function TelemetryPing() {}
 
 TelemetryPing.prototype = {
   _histograms: {},
+  _prevValues: {},
 
   /**
    * Pull values from about:memory into corresponding histograms
@@ -195,7 +197,7 @@ TelemetryPing.prototype = {
             getService(Ci.nsIMemoryReporterManager);
     } catch (e) {
       // OK to skip memory reporters in xpcshell
-      return
+      return;
     }
 
     let e = mgr.enumerateReporters();
@@ -208,14 +210,41 @@ TelemetryPing.prototype = {
         continue;
       }
 
-      let name = "Memory:" + mr.path + " (KB)";
+      let name, val;
+      if (mr.units == Ci.nsIMemoryReporter.UNITS_BYTES) {
+        name = "Memory:" + mr.path + " + (KB)";
+        val = Math.floor(mr.amount / 1024);
+      }
+      else if (mr.units == Ci.nsIMemoryReporter.UNITS_COUNT) {
+        // If the reporter gives us a count, we'll report the difference in its
+        // value between now and our previous ping.
+
+        name = "Memory:" + mr.path;
+
+        // Read mr.amount just once so our arithmetic is consistent.
+        let curVal = mr.amount;
+        let prevVal = this._prevValues[mr.path];
+        if (!prevVal) {
+          // If this is the first time we're reading this reporter, store its
+          // current value but don't report it in the telemetry ping, so we
+          // ignore the effect startup had on the reporter.
+          this._prevValues[mr.path] = curVal;
+          continue;
+        }
+        val = curVal - prevVal;
+        this._prevValues[mr.path] = curVal;
+      }
+      else {
+        NS_ASSERT(false, "Can't handle memory reporter with units " + mr.units);
+        continue;
+      }
+
       let h = this._histograms[name];
       if (!h) {
         h = Telemetry.getHistogramById(id);
         this._histograms[name] = h;
       }
-      let v = Math.floor(mr.amount / 1024);
-      h.add(v);
+      h.add(val);
     }
     return memReporters;
   },
@@ -250,7 +279,7 @@ TelemetryPing.prototype = {
     request.overrideMimeType("text/plain");
     request.setRequestHeader("Content-Type", "application/json");
 
-    let startTime = new Date()
+    let startTime = new Date();
 
     function finishRequest(channel) {
       let success = false;

toolkit/components/telemetry/tests/unit/test_TelemetryPing.js

@@ -87,7 +87,7 @@ function checkHistograms(request, response) {
   const TELEMETRY_SUCCESS = "TELEMETRY_SUCCESS";
   do_check_true(TELEMETRY_PING in payload.histograms)
 
-  // There should be one successful report from the previos telemetry ping
+  // There should be one successful report from the previous telemetry ping.
   const expected_tc = {
     range: [1, 2],
     bucket_count: 3,