Remove memory stats we don't use, move CPU/MemLimit

We will end up caching the CPU and MemLimits so having them separate
makes this easier

checks/container.go

@@ -121,11 +121,11 @@ func fmtContainers(
 			Name:        ctr.Name,
 			Id:          ctr.ID,
 			Image:       ctr.Image,
-			CpuLimit:    float32(ctr.CPU.Limit),
+			CpuLimit:    float32(ctr.CPULimit),
 			UserPct:     calculateCtrPct(ctr.CPU.User, lastCtr.CPU.User, cpus, lastRun),
 			SystemPct:   calculateCtrPct(ctr.CPU.System, lastCtr.CPU.System, cpus, lastRun),
 			TotalPct:    calculateCtrPct(ctr.CPU.User+ctr.CPU.System, lastCtr.CPU.User+lastCtr.CPU.System, cpus, lastRun),
-			MemoryLimit: ctr.Memory.MemLimitInBytes,
+			MemoryLimit: ctr.MemLimit,
 			MemRss:      ctr.Memory.RSS,
 			MemCache:    ctr.Memory.Cache,
 			Created:     ctr.Created,

checks/container_rt.go

@@ -110,10 +110,10 @@ func fmtContainerStats(
 			UserPct:    calculateCtrPct(ctr.CPU.User, lastCtr.CPU.User, cpus, lastRun),
 			SystemPct:  calculateCtrPct(ctr.CPU.System, lastCtr.CPU.System, cpus, lastRun),
 			TotalPct:   calculateCtrPct(ctr.CPU.User+ctr.CPU.System, lastCtr.CPU.User+lastCtr.CPU.System, cpus, lastRun),
-			CpuLimit:   float32(ctr.CPU.Limit),
+			CpuLimit:   float32(ctr.CPULimit),
 			MemRss:     ctr.Memory.RSS,
 			MemCache:   ctr.Memory.Cache,
-			MemLimit:   ctr.Memory.MemLimitInBytes,
+			MemLimit:   ctr.MemLimit,
 			Rbps:       calculateRate(ctr.IO.ReadBytes, lastCtr.IO.ReadBytes, lastRun),
 			Wbps:       calculateRate(ctr.IO.WriteBytes, lastCtr.IO.WriteBytes, lastRun),
 			NetRcvdPs:  calculateRate(ctr.Network.PacketsRcvd, lastCtr.Network.PacketsRcvd, lastRun),

util/docker/cgroup.go

@@ -54,8 +54,6 @@ type CgroupMemStat struct {
 	TotalActiveFile         uint64
 	TotalUnevictable        uint64
 	MemUsageInBytes         uint64
-	MemMaxUsageInBytes      uint64
-	MemLimitInBytes         uint64
 	MemFailCnt              uint64
 }
 
@@ -64,7 +62,6 @@ type CgroupTimesStat struct {
 	ContainerID string
 	System      uint64
 	User        uint64
-	Limit       float64
 }
 
 // CgroupIOStat store I/O statistics about a cgroup.
@@ -162,24 +159,35 @@ func (c ContainerCgroup) Mem() (*CgroupMemStat, error) {
 			ret.TotalUnevictable = v
 		}
 	}
+	return ret, nil
+}
 
-	r, err := c.readCgroupMemFile("memory.usage_in_bytes")
-	if err == nil {
-		ret.MemUsageInBytes = r
+// MemLimit returns the memory limit of the cgroup, if it exists. If the file does not
+// exist or there is no limit then this will default to 0.
+func (c ContainerCgroup) MemLimit() (uint64, error) {
+	statfile, err := c.cgroupFilePath("memory", "memory.limit_in_bytes")
+	if err != nil {
+		return 0, err
+	}
+	lines, err := util.ReadLines(statfile)
+	if os.IsNotExist(err) {
+		return 0, err
+	} else if err != nil {
+		return 0, err
 	}
-	r, err = c.readCgroupMemFile("memory.max_usage_in_bytes")
-	if err == nil {
-		ret.MemMaxUsageInBytes = r
+	if len(lines) != 1 {
+		return 0, fmt.Errorf("wrong format file: %s", statfile)
 	}
-	r, err = c.readCgroupMemFile("memory.limit_in_bytes")
-	if err == nil {
-		ret.MemLimitInBytes = r
+	v, err := strconv.ParseUint(lines[0], 10, 64)
+	if err != nil {
+		return 0, err
 	}
-	r, err = c.readCgroupMemFile("memory.failcnt")
-	if err == nil {
-		ret.MemFailCnt = r
+	// limit_in_bytes is a special case here, it's possible that it shows a ridiculous number,
+	// in which case it represents unlimited, so return 0 here
+	if v > uint64(math.Pow(2, 60)) {
+		v = 0
 	}
-	return ret, nil
+	return v, nil
 }
 
 // CPU returns the CPU status for this cgroup instance
@@ -212,12 +220,6 @@ func (c ContainerCgroup) CPU() (*CgroupTimesStat, error) {
 			}
 		}
 	}
-	limit, err := c.CPULimit()
-	if err != nil {
-		return nil, err
-	}
-	ret.Limit = limit
-
 	return ret, nil
 }
 

util/docker/docker.go

@@ -154,10 +154,12 @@ type Container struct {
 	Health  string
 	Pids    []int32
 
-	CPU     *CgroupTimesStat
-	Memory  *CgroupMemStat
-	IO      *CgroupIOStat
-	Network *NetworkStat
+	CPULimit float64
+	MemLimit uint64
+	CPU      *CgroupTimesStat
+	Memory   *CgroupMemStat
+	IO       *CgroupIOStat
+	Network  *NetworkStat
 }
 
 type dockerNetwork struct {
@@ -385,6 +387,14 @@ func (d *dockerUtil) containers(pids []int32) ([]*Container, error) {
 		if err != nil {
 			return nil, err
 		}
+		container.CPULimit, err = cgroup.CPULimit()
+		if err != nil {
+			return nil, err
+		}
+		container.MemLimit, err = cgroup.MemLimit()
+		if err != nil {
+			return nil, err
+		}
 
 		if d.cfg.CollectNetwork {
 			d.Lock()