1 files changed, 34 insertions, 2 deletions

diff --git a/lib/perf_hooks.js b/lib/perf_hooks.js
index 2ce0d29464a..683dec3a90a 100644
--- a/lib/perf_hooks.js
+++ b/lib/perf_hooks.js
@@ -25,7 +25,8 @@ const {
   timerify,
   constants,
   installGarbageCollectionTracking,
-  removeGarbageCollectionTracking
+  removeGarbageCollectionTracking,
+  loopIdleTime,
 } = internalBinding('performance');
 
 const {
@@ -205,6 +206,10 @@ class PerformanceNodeTiming extends PerformanceEntry {
     return getMilestoneTimestamp(NODE_PERFORMANCE_MILESTONE_BOOTSTRAP_COMPLETE);
   }
 
+  get idleTime() {
+    return loopIdleTime();
+  }
+
   [kInspect]() {
     return {
       name: 'node',
@@ -448,10 +453,37 @@ class Performance {
     return ret;
   }
 
+  eventLoopUtilization(util1, util2) {
+    const ls = nodeTiming.loopStart;
+
+    if (ls <= 0) {
+      return { idle: 0, active: 0, utilization: 0 };
+    }
+
+    if (util2) {
+      const idle = util1.idle - util2.idle;
+      const active = util1.active - util2.active;
+      return { idle, active, utilization: active / (idle + active) };
+    }
+
+    const idle = nodeTiming.idleTime;
+    const active = performance.now() - ls - idle;
+
+    if (!util1) {
+      return { idle, active, utilization: active / (idle + active) };
+    }
+
+    const idle_delta = idle - util1.idle;
+    const active_delta = active - util1.active;
+    const utilization = active_delta / (idle_delta + active_delta);
+    return { idle: idle_delta, active: active_delta, utilization };
+  }
+
   [kInspect]() {
     return {
       nodeTiming: this.nodeTiming,
-      timeOrigin: this.timeOrigin
+      timeOrigin: this.timeOrigin,
+      idleTime: this.idleTime,
     };
   }
 }