From 5d29598a6d5db2405befb15c83c7f95cd42ae5fe Mon Sep 17 00:00:00 2001
From: Lantao Liu <lantaol@google.com>
Date: Fri, 11 May 2018 14:57:13 -0700
Subject: [PATCH] Fix workingset memory calculation.

Signed-off-by: Lantao Liu <lantaol@google.com>
---
 pkg/server/container_stats_list.go      | 20 ++++++++-
 pkg/server/container_stats_list_test.go | 55 +++++++++++++++++++++++++
 2 files changed, 73 insertions(+), 2 deletions(-)
 create mode 100644 pkg/server/container_stats_list_test.go

diff --git a/pkg/server/container_stats_list.go b/pkg/server/container_stats_list.go
index 3b4d8c93d..f0605ef77 100644
--- a/pkg/server/container_stats_list.go
+++ b/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
+}
diff --git a/pkg/server/container_stats_list_test.go b/pkg/server/container_stats_list_test.go
new file mode 100644
index 000000000..9774ee4b8
--- /dev/null
+++ b/pkg/server/container_stats_list_test.go
@@ -0,0 +1,55 @@
+/*
+Copyright 2018 The containerd Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package server
+
+import (
+	"testing"
+
+	"github.com/containerd/cgroups"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetWorkingSet(t *testing.T) {
+	for desc, test := range map[string]struct {
+		memory   *cgroups.MemoryStat
+		expected uint64
+	}{
+		"nil memory usage": {
+			memory:   &cgroups.MemoryStat{},
+			expected: 0,
+		},
+		"memory usage higher than inactive_total_file": {
+			memory: &cgroups.MemoryStat{
+				TotalInactiveFile: 1000,
+				Usage:             &cgroups.MemoryEntry{Usage: 2000},
+			},
+			expected: 1000,
+		},
+		"memory usage lower than inactive_total_file": {
+			memory: &cgroups.MemoryStat{
+				TotalInactiveFile: 2000,
+				Usage:             &cgroups.MemoryEntry{Usage: 1000},
+			},
+			expected: 0,
+		},
+	} {
+		t.Run(desc, func(t *testing.T) {
+			got := getWorkingSet(test.memory)
+			assert.Equal(t, test.expected, got)
+		})
+	}
+}