Avoid small changes when ideal is off limits

3 files changed, 22 insertions, 21 deletions

diff --git a/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/autoscale/AllocatableClusterResources.java b/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/autoscale/AllocatableClusterResources.java
index 0e4cc8390a2..5ca09ddf51c 100644
--- a/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/autoscale/AllocatableClusterResources.java
+++ b/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/autoscale/AllocatableClusterResources.java
@@ -116,7 +116,9 @@ public class AllocatableClusterResources {
 
     @Override
     public String toString() {
-        return "$" + cost() + " (fulfilment " + fulfilment + "): " + realResources();
+        return nodes + " nodes with " + realResources() +
+               " at cost $" + cost() +
+               (fulfilment < 1.0 ? " (fulfilment " + fulfilment + ")" : "");
     }
 
 }
diff --git a/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/autoscale/Autoscaler.java b/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/autoscale/Autoscaler.java
index 9fe1b4ac55d..e8796820fa9 100644
--- a/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/autoscale/Autoscaler.java
+++ b/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/autoscale/Autoscaler.java
@@ -37,10 +37,10 @@ public class Autoscaler {
 
     private static final int minimumMeasurements = 500; // TODO: Per node instead? Also say something about interval?
 
-    /** What cost difference factor warrants reallocation? */
-    private static final double costDifferenceRatioWorthReallocation = 0.1;
-    /** What difference factor from ideal (for any resource) warrants a change? */
-    private static final double idealDivergenceWorthReallocation = 0.1;
+    /** What cost difference factor is worth a reallocation? */
+    private static final double costDifferenceWorthReallocation = 0.1;
+    /** What difference factor for a resource is worth a reallocation? */
+    private static final double resourceDifferenceWorthReallocation = 0.1;
 
     private final HostResourcesCalculator resourcesCalculator;
     private final NodeMetricsDb metricsDb;
@@ -82,13 +82,7 @@ public class Autoscaler {
                                                                                   currentAllocation,
                                                                                   cluster);
         if (bestAllocation.isEmpty()) return Optional.empty();
-
-        if (closeToIdeal(Resource.cpu, cpuLoad.get()) &&
-            closeToIdeal(Resource.memory, memoryLoad.get()) &&
-            closeToIdeal(Resource.disk, diskLoad.get()) &&
-            similarCost(bestAllocation.get().cost(), currentAllocation.cost())) {
-            return Optional.empty(); // Avoid small, unnecessary changes
-        }
+        if (similar(bestAllocation.get(), currentAllocation)) return Optional.empty();
         return bestAllocation;
     }
 
@@ -107,12 +101,16 @@ public class Autoscaler {
         return bestAllocation;
     }
 
-    private boolean similarCost(double cost1, double cost2) {
-        return similar(cost1, cost2, costDifferenceRatioWorthReallocation);
-    }
-
-    private boolean closeToIdeal(Resource resource, double value) {
-        return similar(resource.idealAverageLoad(), value, idealDivergenceWorthReallocation);
+    /** Returns true if both total real resources and total cost are similar */
+    private boolean similar(AllocatableClusterResources a, AllocatableClusterResources b) {
+        return similar(a.cost(), b.cost(), costDifferenceWorthReallocation) &&
+               similar(a.realResources().vcpu() * a.nodes(),
+                       b.realResources().vcpu() * b.nodes(), resourceDifferenceWorthReallocation) &&
+               similar(a.realResources().memoryGb() * a.nodes(),
+                       b.realResources().memoryGb() * b.nodes(), resourceDifferenceWorthReallocation) &&
+               similar(a.realResources().diskGb() * a.nodes(),
+                       b.realResources().diskGb() * b.nodes(),
+                       resourceDifferenceWorthReallocation);
     }
 
     private boolean similar(double r1, double r2, double threshold) {
diff --git a/node-repository/src/test/java/com/yahoo/vespa/hosted/provision/autoscale/AutoscalingTest.java b/node-repository/src/test/java/com/yahoo/vespa/hosted/provision/autoscale/AutoscalingTest.java
index 3bb0676da4f..8bfb17c0bd4 100644
--- a/node-repository/src/test/java/com/yahoo/vespa/hosted/provision/autoscale/AutoscalingTest.java
+++ b/node-repository/src/test/java/com/yahoo/vespa/hosted/provision/autoscale/AutoscalingTest.java
@@ -99,16 +99,17 @@ public class AutoscalingTest {
 
     @Test
     public void testAutoscalingRespectsUpperLimit() {
-        NodeResources resources = new NodeResources(3, 100, 100, 1);
+        NodeResources hostResources = new NodeResources(3, 100, 100, 1);
         ClusterResources min = new ClusterResources( 2, 1, new NodeResources(1, 1, 1, 1));
         ClusterResources max = new ClusterResources( 6, 1, new NodeResources(2.4, 78, 79, 1));
-        AutoscalingTester tester = new AutoscalingTester(resources);
+        AutoscalingTester tester = new AutoscalingTester(hostResources);
 
         ApplicationId application1 = tester.applicationId("application1");
         ClusterSpec cluster1 = tester.clusterSpec(ClusterSpec.Type.container, "cluster1");
 
         // deploy
-        tester.deploy(application1, cluster1, 5, 1, resources);
+        tester.deploy(application1, cluster1, 5, 1,
+                      new NodeResources(1.9, 70, 70, 1));
         tester.addMeasurements(Resource.cpu,    0.25f, 120, application1);
         tester.addMeasurements(Resource.memory, 0.95f, 120, application1);
         tester.addMeasurements(Resource.disk,   0.95f, 120, application1);