diff --git a/hadoop-yarn-project/CHANGES.txt b/hadoop-yarn-project/CHANGES.txt
index f8499603db..0afc4cf735 100644
--- a/hadoop-yarn-project/CHANGES.txt
+++ b/hadoop-yarn-project/CHANGES.txt
@@ -180,6 +180,9 @@ Release 2.7.0 - UNRELEASED
     YARN-2957. Create unit test to automatically compare YarnConfiguration
     and yarn-default.xml. (rchiang via rkanter)
 
+    YARN-2643. Don't create a new DominantResourceCalculator on every
+    FairScheduler.allocate call. (kasha via rkanter)
+
   OPTIMIZATIONS
 
   BUG FIXES
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FairScheduler.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FairScheduler.java
index 2f0857e18f..1ace6040b2 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FairScheduler.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FairScheduler.java
@@ -127,6 +127,8 @@ public class FairScheduler extends
   
   private static final ResourceCalculator RESOURCE_CALCULATOR =
       new DefaultResourceCalculator();
+  private static final ResourceCalculator DOMINANT_RESOURCE_CALCULATOR =
+      new DominantResourceCalculator();
   
   // Value that container assignment methods return when a container is
   // reserved
@@ -878,7 +880,8 @@ private synchronized void removeNode(RMNode rmNode) {
 
   @Override
   public Allocation allocate(ApplicationAttemptId appAttemptId,
-      List<ResourceRequest> ask, List<ContainerId> release, List<String> blacklistAdditions, List<String> blacklistRemovals) {
+      List<ResourceRequest> ask, List<ContainerId> release,
+      List<String> blacklistAdditions, List<String> blacklistRemovals) {
 
     // Make sure this application exists
     FSAppAttempt application = getSchedulerApp(appAttemptId);
@@ -889,7 +892,7 @@ public Allocation allocate(ApplicationAttemptId appAttemptId,
     }
 
     // Sanity check
-    SchedulerUtils.normalizeRequests(ask, new DominantResourceCalculator(),
+    SchedulerUtils.normalizeRequests(ask, DOMINANT_RESOURCE_CALCULATOR,
         clusterResource, minimumAllocation, getMaximumResourceCapability(),
         incrAllocation);