libct/cg: add CFS bandwidth burst for CPU

contrib/completions/bash/runc

@@ -732,6 +732,7 @@ _runc_update() {
 	   --blkio-weight
 	   --cpu-period
 	   --cpu-quota
+	   --cpu-burst
 	   --cpu-rt-period
 	   --cpu-rt-runtime
 	   --cpu-share

libcontainer/cgroups/fs/cpu.go

@@ -84,6 +84,23 @@ func (s *CpuGroup) Set(path string, r *configs.Resources) error {
 			period = ""
 		}
 	}
+
+	var burst string
+	burst = strconv.FormatUint(r.CpuBurst, 10)
+	if err := cgroups.WriteFile(path, "cpu.cfs_burst_us", burst); err != nil {
+		// Sometimes when the burst to be set is larger
+		// than the current one, it is rejected by the kernel
+		// (EINVAL) as old_quota/new_burst exceeds the parent
+		// cgroup quota limit. If this happens and the quota is
+		// going to be set, ignore the error for now and retry
+		// after setting the quota.
+		if !errors.Is(err, unix.EINVAL) || r.CpuQuota == 0 {
+			return err
+		}
+	} else {
+		burst = ""
+	}
+
 	if r.CpuQuota != 0 {
 		if err := cgroups.WriteFile(path, "cpu.cfs_quota_us", strconv.FormatInt(r.CpuQuota, 10)); err != nil {
 			return err
@@ -93,7 +110,13 @@ func (s *CpuGroup) Set(path string, r *configs.Resources) error {
 				return err
 			}
 		}
+		if burst != "" {
+			if err := cgroups.WriteFile(path, "cpu.cfs_burst_us", burst); err != nil {
+				return err
+			}
+		}
 	}
+
 	return s.SetRtSched(path, r)
 }
 

libcontainer/cgroups/fs/cpu_test.go

@@ -45,6 +45,8 @@ func TestCpuSetBandWidth(t *testing.T) {
 	const (
 		quotaBefore     = 8000
 		quotaAfter      = 5000
+		burstBefore     = 2000
+		burstAfter      = 1000
 		periodBefore    = 10000
 		periodAfter     = 7000
 		rtRuntimeBefore = 8000
@@ -55,13 +57,15 @@ func TestCpuSetBandWidth(t *testing.T) {
 
 	writeFileContents(t, path, map[string]string{
 		"cpu.cfs_quota_us":  strconv.Itoa(quotaBefore),
+		"cpu.cfs_burst_us":  strconv.Itoa(burstBefore),
 		"cpu.cfs_period_us": strconv.Itoa(periodBefore),
 		"cpu.rt_runtime_us": strconv.Itoa(rtRuntimeBefore),
 		"cpu.rt_period_us":  strconv.Itoa(rtPeriodBefore),
 	})
 
 	r := &configs.Resources{
 		CpuQuota:     quotaAfter,
+		CpuBurst:     burstAfter,
 		CpuPeriod:    periodAfter,
 		CpuRtRuntime: rtRuntimeAfter,
 		CpuRtPeriod:  rtPeriodAfter,
@@ -79,6 +83,14 @@ func TestCpuSetBandWidth(t *testing.T) {
 		t.Fatal("Got the wrong value, set cpu.cfs_quota_us failed.")
 	}
 
+	burst, err := fscommon.GetCgroupParamUint(path, "cpu.cfs_burst_us")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if burst != burstAfter {
+		t.Fatal("Got the wrong value, set cpu.cfs_burst_us failed.")
+	}
+
 	period, err := fscommon.GetCgroupParamUint(path, "cpu.cfs_period_us")
 	if err != nil {
 		t.Fatal(err)

libcontainer/cgroups/fs2/cpu.go

@@ -2,16 +2,18 @@ package fs2
 
 import (
 	"bufio"
+	"errors"
 	"os"
 	"strconv"
 
 	"github.com/opencontainers/runc/libcontainer/cgroups"
 	"github.com/opencontainers/runc/libcontainer/cgroups/fscommon"
 	"github.com/opencontainers/runc/libcontainer/configs"
+	"golang.org/x/sys/unix"
 )
 
 func isCpuSet(r *configs.Resources) bool {
-	return r.CpuWeight != 0 || r.CpuQuota != 0 || r.CpuPeriod != 0
+	return r.CpuWeight != 0 || r.CpuQuota != 0 || r.CpuPeriod != 0 || r.CpuBurst != 0
 }
 
 func setCpu(dirPath string, r *configs.Resources) error {
@@ -26,6 +28,22 @@ func setCpu(dirPath string, r *configs.Resources) error {
 		}
 	}
 
+	var burst string
+	burst = strconv.FormatUint(r.CpuBurst, 10)
+	if err := cgroups.WriteFile(dirPath, "cpu.max.burst", burst); err != nil {
+		// Sometimes when the burst to be set is larger
+		// than the current one, it is rejected by the kernel
+		// (EINVAL) as old_quota/new_burst exceeds the parent
+		// cgroup quota limit. If this happens and the quota is
+		// going to be set, ignore the error for now and retry
+		// after setting the quota.
+		if !errors.Is(err, unix.EINVAL) || r.CpuQuota == 0 {
+			return err
+		}
+	} else {
+		burst = ""
+	}
+
 	if r.CpuQuota != 0 || r.CpuPeriod != 0 {
 		str := "max"
 		if r.CpuQuota > 0 {
@@ -41,6 +59,11 @@ func setCpu(dirPath string, r *configs.Resources) error {
 		if err := cgroups.WriteFile(dirPath, "cpu.max", str); err != nil {
 			return err
 		}
+		if burst != "" {
+			if err := cgroups.WriteFile(dirPath, "cpu.max.burst", burst); err != nil {
+				return err
+			}
+		}
 	}
 
 	return nil

libcontainer/configs/cgroup_linux.go

@@ -69,6 +69,9 @@ type Resources struct {
 	// CPU hardcap limit (in usecs). Allowed cpu time in a given period.
 	CpuQuota int64 `json:"cpu_quota"`
 
+	// CPU hardcap burst limit (in usecs). Allowed accumulated cpu time additionally for burst in a given period.
+	CpuBurst uint64 `json:"cpu_burst"`
+
 	// CPU period to be used for hardcapping (in usecs). 0 to use system default.
 	CpuPeriod uint64 `json:"cpu_period"`
 

libcontainer/specconv/spec_linux.go

@@ -737,6 +737,9 @@ func CreateCgroupConfig(opts *CreateOpts, defaultDevs []*devices.Device) (*confi
 				if r.CPU.Quota != nil {
 					c.Resources.CpuQuota = *r.CPU.Quota
 				}
+				if r.CPU.Burst != nil {
+					c.Resources.CpuBurst = *r.CPU.Burst
+				}
 				if r.CPU.Period != nil {
 					c.Resources.CpuPeriod = *r.CPU.Period
 				}

man/runc-update.8.md

@@ -28,6 +28,7 @@ In case **-r** is used, the JSON format is like this:
 			"cpu": {
 				"shares": 0,
 				"quota": 0,
+				"burst": 0,
 				"period": 0,
 				"realtimeRuntime": 0,
 				"realtimePeriod": 0,
@@ -53,6 +54,9 @@ stdin. If this option is used, all other options are ignored.
 **--cpu-quota** _num_
 : Set CPU usage limit within a given period (in microseconds).
 
+**--cpu-burst** _num_
+: Set CPU burst limit within a given period (in microseconds).
+
 **--cpu-rt-period** _num_
 : Set CPU realtime period to be used for hardcapping (in microseconds).
 

update.go

@@ -44,6 +44,7 @@ The accepted format is as follow (unchanged values can be omitted):
   "cpu": {
     "shares": 0,
     "quota": 0,
+    "burst": 0,
     "period": 0,
     "realtimeRuntime": 0,
     "realtimePeriod": 0,
@@ -72,6 +73,10 @@ other options are ignored.
 			Name:  "cpu-quota",
 			Usage: "CPU CFS hardcap limit (in usecs). Allowed cpu time in a given period",
 		},
+		cli.StringFlag{
+			Name:  "cpu-burst",
+			Usage: "CPU CFS hardcap burst limit (in usecs). Allowed accumulated cpu time additionally for burst a given period",
+		},
 		cli.StringFlag{
 			Name:  "cpu-share",
 			Usage: "CPU shares (relative weight vs. other containers)",
@@ -148,6 +153,7 @@ other options are ignored.
 			CPU: &specs.LinuxCPU{
 				Shares:          u64Ptr(0),
 				Quota:           i64Ptr(0),
+				Burst:           u64Ptr(0),
 				Period:          u64Ptr(0),
 				RealtimeRuntime: i64Ptr(0),
 				RealtimePeriod:  u64Ptr(0),
@@ -197,6 +203,7 @@ other options are ignored.
 				opt  string
 				dest *uint64
 			}{
+				{"cpu-burst", r.CPU.Burst},
 				{"cpu-period", r.CPU.Period},
 				{"cpu-rt-period", r.CPU.RealtimePeriod},
 				{"cpu-share", r.CPU.Shares},
@@ -286,6 +293,12 @@ other options are ignored.
 			}
 		}
 
+		b := *r.CPU.Burst
+		if config.Cgroups.Resources.CpuPeriod == 0 && b != 0 {
+			return errors.New("period is not set when setting burst")
+		}
+		config.Cgroups.Resources.CpuBurst = b
+
 		config.Cgroups.Resources.CpuShares = *r.CPU.Shares
 		// CpuWeight is used for cgroupv2 and should be converted
 		config.Cgroups.Resources.CpuWeight = cgroups.ConvertCPUSharesToCgroupV2Value(*r.CPU.Shares)