From: Pavlo Kushnir <pavlo@fb.com>
Date: Thu, 29 Oct 2015 00:15:19 +0000 (-0700)
Subject: Do not set startWork_ in EventBase if time measurement is disabled
X-Git-Tag: deprecate-dynamic-initializer~289
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=af3fa519ac83267fabc53d3799a57dab761de0bc;p=folly.git

Do not set startWork_ in EventBase if time measurement is disabled

Summary: startWork_ is used only if enableTimeMeasurement is set. It gives ~0.5% performance win for mcrouter.

Reviewed By: yfeldblum

Differential Revision: D2590176

fb-gh-sync-id: 07f2189ebdec751cd0d91d191d8f595780d2808a
---

diff --git a/folly/io/async/EventBase.cpp b/folly/io/async/EventBase.cpp
index 2ec1e90d..55691b19 100644
--- a/folly/io/async/EventBase.cpp
+++ b/folly/io/async/EventBase.cpp
@@ -459,12 +459,14 @@ bool EventBase::bumpHandlingTime() {
     " (loop) latest " << latestLoopCnt_ << " next " << nextLoopCnt_;
   if(nothingHandledYet()) {
     latestLoopCnt_ = nextLoopCnt_;
-    // set the time
-    startWork_ = std::chrono::duration_cast<std::chrono::microseconds>(
-      std::chrono::steady_clock::now().time_since_epoch()).count();
+    if (enableTimeMeasurement_) {
+      // set the time
+      startWork_ = std::chrono::duration_cast<std::chrono::microseconds>(
+        std::chrono::steady_clock::now().time_since_epoch()).count();
 
-    VLOG(11) << "EventBase " << this << " " << __PRETTY_FUNCTION__ <<
-      " (loop) startWork_ " << startWork_;
+      VLOG(11) << "EventBase " << this << " " << __PRETTY_FUNCTION__ <<
+        " (loop) startWork_ " << startWork_;
+    }
     return true;
   }
   return false;