Added resource overcommit support to the binpacking strategy.

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>

scheduler/strategy/binpacking.go

@@ -13,14 +13,19 @@ var (
 )
 
 type BinPackingPlacementStrategy struct {
+	OvercommitRatio float64
 }
 
 func (p *BinPackingPlacementStrategy) PlaceContainer(config *dockerclient.ContainerConfig, nodes []*cluster.Node) (*cluster.Node, error) {
 	scores := scores{}
 
+	ratio := int64(p.OvercommitRatio * 100)
 	for _, node := range nodes {
+		nodeMemory := node.Memory + (node.Memory * ratio / 100)
+		nodeCpus := node.Cpus + (node.Cpus * ratio / 100)
+
 		// Skip nodes that are smaller than the requested resources.
-		if node.Memory < int64(config.Memory) || node.Cpus < config.CpuShares {
+		if nodeMemory < int64(config.Memory) || nodeCpus < config.CpuShares {
 			continue
 		}
 
@@ -30,10 +35,10 @@ func (p *BinPackingPlacementStrategy) PlaceContainer(config *dockerclient.Contai
 		)
 
 		if config.CpuShares > 0 {
-			cpuScore = (node.ReservedCpus() + config.CpuShares) * 100 / node.Cpus
+			cpuScore = (node.ReservedCpus() + config.CpuShares) * 100 / nodeCpus
 		}
 		if config.Memory > 0 {
-			memoryScore = (node.ReservedMemory() + config.Memory) * 100 / node.Memory
+			memoryScore = (node.ReservedMemory() + config.Memory) * 100 / nodeMemory
 		}
 		var total = ((cpuScore + memoryScore) / 200) * 100
 

scheduler/strategy/binpacking_test.go

@@ -52,7 +52,6 @@ func TestPlaceContainerMemory(t *testing.T) {
 	// check that both containers ended on the same node
 	assert.Equal(t, node1.ID, node2.ID, "")
 	assert.Equal(t, len(node1.Containers()), len(node2.Containers()), "")
-
 }
 
 func TestPlaceContainerCPU(t *testing.T) {
@@ -82,7 +81,6 @@ func TestPlaceContainerCPU(t *testing.T) {
 	// check that both containers ended on the same node
 	assert.Equal(t, node1.ID, node2.ID, "")
 	assert.Equal(t, len(node1.Containers()), len(node2.Containers()), "")
-
 }
 
 func TestPlaceContainerHuge(t *testing.T) {
@@ -114,7 +112,38 @@ func TestPlaceContainerHuge(t *testing.T) {
 	// try to add another container 1G
 	_, err = s.PlaceContainer(createConfig(1, 0), nodes)
 	assert.Error(t, err)
+}
 
+func TestPlaceContainerOvercommit(t *testing.T) {
+	s := &BinPackingPlacementStrategy{OvercommitRatio: 0.05}
+
+	nodes := []*cluster.Node{createNode("node-1", 0, 1)}
+	nodes[0].Memory = 100
+
+	config := createConfig(0, 0)
+
+	// Below limit should still work.
+	config.Memory = 90
+	node, err := s.PlaceContainer(config, nodes)
+	assert.NoError(t, err)
+	assert.Equal(t, node, nodes[0])
+
+	// At memory limit should still work.
+	config.Memory = 100
+	node, err = s.PlaceContainer(config, nodes)
+	assert.NoError(t, err)
+	assert.Equal(t, node, nodes[0])
+
+	// Up to 105% it should still work.
+	config.Memory = 105
+	node, err = s.PlaceContainer(config, nodes)
+	assert.NoError(t, err)
+	assert.Equal(t, node, nodes[0])
+
+	// Above it should return an error.
+	config.Memory = 106
+	node, err = s.PlaceContainer(config, nodes)
+	assert.Error(t, err)
 }
 
 // The demo