diff --git a/cadvisor b/cadvisor
deleted file mode 100755
index 15b16f30..00000000
Binary files a/cadvisor and /dev/null differ
diff --git a/info/container.go b/info/container.go
index 94c7c657..3e2447d9 100644
--- a/info/container.go
+++ b/info/container.go
@@ -119,7 +119,7 @@ type CpuStats struct {
 
 		// Per CPU/core usage of the container.
 		// Unit: nanoseconds.
-		PerCpu []uint64 `json:"per_cpu,omitempty"`
+		PerCpu []uint64 `json:"per_cpu_usage,omitempty"`
 
 		// Time spent in user space.
 		// Unit: nanoseconds
@@ -173,6 +173,9 @@ type ContainerStatsSample struct {
 	Cpu      struct {
 		// number of nanoseconds of CPU time used by the container
 		Usage uint64 `json:"usage"`
+
+		// Per-core usage of the container. (unit: nanoseconds)
+		PerCpuUsage []uint64 `json:"per_cpu_usage,omitempty"`
 	} `json:"cpu"`
 	Memory struct {
 		// Units: Bytes.
@@ -211,9 +214,28 @@ func NewSample(prev, current *ContainerStats) (*ContainerStatsSample, error) {
 	if current.Cpu.Usage.Total < prev.Cpu.Usage.Total {
 		return nil, fmt.Errorf("current CPU usage is less than prev CPU usage (cumulative).")
 	}
+
+	var percpu []uint64
+
+	if len(current.Cpu.Usage.PerCpu) > 0 {
+		curNumCpus := len(current.Cpu.Usage.PerCpu)
+		percpu = make([]uint64, curNumCpus)
+
+		for i, currUsage := range current.Cpu.Usage.PerCpu {
+			var prevUsage uint64 = 0
+			if i < len(prev.Cpu.Usage.PerCpu) {
+				prevUsage = prev.Cpu.Usage.PerCpu[i]
+			}
+			if currUsage < prevUsage {
+				return nil, fmt.Errorf("current per-core CPU usage is less than prev per-core CPU usage (cumulative).")
+			}
+			percpu[i] = currUsage - prevUsage
+		}
+	}
 	sample := new(ContainerStatsSample)
 	// Calculate the diff to get the CPU usage within the time interval.
 	sample.Cpu.Usage = current.Cpu.Usage.Total - prev.Cpu.Usage.Total
+	sample.Cpu.PerCpuUsage = percpu
 	// Memory usage is current memory usage
 	sample.Memory.Usage = current.Memory.Usage
 	sample.Timestamp = current.Timestamp
diff --git a/info/container_test.go b/info/container_test.go
index 4b275bec..071ed914 100644
--- a/info/container_test.go
+++ b/info/container_test.go
@@ -230,3 +230,50 @@ func TestAddSampleWrongCpuUsage(t *testing.T) {
 		t.Errorf("generated an unexpected sample: %+v", sample)
 	}
 }
+
+func TestAddSampleHotPluggingCpu(t *testing.T) {
+	cpuPrevUsage := uint64(10)
+	cpuCurrentUsage := uint64(15)
+	memCurrentUsage := uint64(200)
+	prevTime := time.Now()
+
+	prev := createStats(cpuPrevUsage, memCurrentUsage, prevTime)
+	current := createStats(cpuCurrentUsage, memCurrentUsage, prevTime.Add(1*time.Second))
+	current.Cpu.Usage.PerCpu = append(current.Cpu.Usage.PerCpu, 10)
+
+	sample, err := NewSample(prev, current)
+	if err != nil {
+		t.Errorf("should be able to generate a sample. but received error: %v", err)
+	}
+	if len(sample.Cpu.PerCpuUsage) != 2 {
+		t.Fatalf("Should have 2 cores.")
+	}
+	if sample.Cpu.PerCpuUsage[0] != cpuCurrentUsage-cpuPrevUsage {
+		t.Errorf("First cpu usage is %v. should be %v", sample.Cpu.PerCpuUsage[0], cpuCurrentUsage-cpuPrevUsage)
+	}
+	if sample.Cpu.PerCpuUsage[1] != 10 {
+		t.Errorf("Second cpu usage is %v. should be 10", sample.Cpu.PerCpuUsage[1])
+	}
+}
+
+func TestAddSampleHotUnpluggingCpu(t *testing.T) {
+	cpuPrevUsage := uint64(10)
+	cpuCurrentUsage := uint64(15)
+	memCurrentUsage := uint64(200)
+	prevTime := time.Now()
+
+	prev := createStats(cpuPrevUsage, memCurrentUsage, prevTime)
+	current := createStats(cpuCurrentUsage, memCurrentUsage, prevTime.Add(1*time.Second))
+	prev.Cpu.Usage.PerCpu = append(prev.Cpu.Usage.PerCpu, 10)
+
+	sample, err := NewSample(prev, current)
+	if err != nil {
+		t.Errorf("should be able to generate a sample. but received error: %v", err)
+	}
+	if len(sample.Cpu.PerCpuUsage) != 1 {
+		t.Fatalf("Should have 1 cores.")
+	}
+	if sample.Cpu.PerCpuUsage[0] != cpuCurrentUsage-cpuPrevUsage {
+		t.Errorf("First cpu usage is %v. should be %v", sample.Cpu.PerCpuUsage[0], cpuCurrentUsage-cpuPrevUsage)
+	}
+}
diff --git a/storage/test/storagetests.go b/storage/test/storagetests.go
index 7a45cc8a..9c4ec0ae 100644
--- a/storage/test/storagetests.go
+++ b/storage/test/storagetests.go
@@ -44,7 +44,7 @@ func buildTrace(cpu, mem []uint64, duration time.Duration) []*info.ContainerStat
 		stats.Cpu.Usage.Total = cpuTotalUsage
 		stats.Cpu.Usage.User = stats.Cpu.Usage.Total
 		stats.Cpu.Usage.System = 0
-		stats.Cpu.Usage.PerCpu = []uint64{cpuUsage}
+		stats.Cpu.Usage.PerCpu = []uint64{cpuTotalUsage}
 
 		stats.Memory.Usage = mem[i]