Change calculation of memory usage. (#1892)

docker/calculation.go

@@ -0,0 +1,17 @@
+package docker
+
+import "github.com/docker/docker/api/types"
+
+func calculateMemUsageUnixNoCache(mem types.MemoryStats) float64 {
+	// re implementation of the docker calculation
+	// https://github.com/docker/cli/blob/53f8ed4bec07084db4208f55987a2ea94b7f01d6/cli/command/container/stats_helpers.go#L227-L249
+	// cgroup v1
+	if v, isCGroup := mem.Stats["total_inactive_file"]; isCGroup && v < mem.Usage {
+		return float64(mem.Usage - v)
+	}
+	// cgroup v2
+	if v := mem.Stats["inactive_file"]; v < mem.Usage {
+		return float64(mem.Usage - v)
+	}
+	return float64(mem.Usage)
+}

docker/calculation_test.go

@@ -0,0 +1,57 @@
+package docker
+
+import (
+	"github.com/docker/docker/api/types"
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func Test_calculateMemUsageUnixNoCache(t *testing.T) {
+	type args struct {
+		mem types.MemoryStats
+	}
+	tests := []struct {
+		name string
+		args args
+		want float64
+	}{
+		{
+			name: "with cgroup v1",
+			args: args{
+				mem: types.MemoryStats{
+					Usage: 100,
+					Stats: map[string]uint64{
+						"total_inactive_file": 1,
+					},
+				},
+			},
+			want: 99,
+		},
+		{
+			name: "with cgroup v2",
+			args: args{
+				mem: types.MemoryStats{
+					Usage: 100,
+					Stats: map[string]uint64{
+						"inactive_file": 2,
+					},
+				},
+			},
+			want: 98,
+		},
+		{
+			name: "without cgroup",
+			args: args{
+				mem: types.MemoryStats{
+					Usage: 100,
+				},
+			},
+			want: 100,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equalf(t, tt.want, calculateMemUsageUnixNoCache(tt.args.mem), "calculateMemUsageUnixNoCache(%v)", tt.args.mem)
+		})
+	}
+}

docker/client.go

@@ -147,7 +147,7 @@ func (d *dockerClient) ContainerStats(ctx context.Context, id string, stats chan
 				cpuDelta    = float64(v.CPUStats.CPUUsage.TotalUsage) - float64(v.PreCPUStats.CPUUsage.TotalUsage)
 				systemDelta = float64(v.CPUStats.SystemUsage) - float64(v.PreCPUStats.SystemUsage)
 				cpuPercent  = int64((cpuDelta / systemDelta) * float64(ncpus) * 100)
-				memUsage    = int64(v.MemoryStats.Usage - v.MemoryStats.Stats["cache"])
+				memUsage    = int64(calculateMemUsageUnixNoCache(v.MemoryStats))
 				memPercent  = int64(float64(memUsage) / float64(v.MemoryStats.Limit) * 100)
 			)