Fix workingset memory calculation.

Signed-off-by: Lantao Liu <lantaol@google.com>

pkg/server/container_stats_list.go

@@ -109,8 +109,10 @@ func (c *criService) getContainerMetrics(
 		}
 		if metrics.Memory != nil && metrics.Memory.Usage != nil {
 			cs.Memory = &runtime.MemoryUsage{
-				Timestamp:       stats.Timestamp.UnixNano(),
-				WorkingSetBytes: &runtime.UInt64Value{Value: metrics.Memory.Usage.Usage},
+				Timestamp: stats.Timestamp.UnixNano(),
+				WorkingSetBytes: &runtime.UInt64Value{
+					Value: getWorkingSet(metrics.Memory),
+				},
 			}
 		}
 	}
@@ -167,3 +169,17 @@ func matchLabelSelector(selector, labels map[string]string) bool {
 	}
 	return true
 }
+
+// getWorkingSet calculates workingset memory from cgroup memory stats.
+// The caller should make sure memory is not nil.
+// workingset = usage - total_inactive_file
+func getWorkingSet(memory *cgroups.MemoryStat) uint64 {
+	if memory.Usage == nil {
+		return 0
+	}
+	var workingSet uint64
+	if memory.TotalInactiveFile < memory.Usage.Usage {
+		workingSet = memory.Usage.Usage - memory.TotalInactiveFile
+	}
+	return workingSet
+}