cgroup2: add CpuMax conversion

Fix #2243

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

libcontainer/cgroups/fs2/cpu.go

@@ -14,12 +14,14 @@ import (
 )
 
 func setCpu(dirPath string, cgroup *configs.Cgroup) error {
+	// NOTE: .CpuShares is not used here. Conversion is the caller's responsibility.
 	if cgroup.Resources.CpuWeight != 0 {
 		if err := fscommon.WriteFile(dirPath, "cpu.weight", strconv.FormatUint(cgroup.Resources.CpuWeight, 10)); err != nil {
 			return err
 		}
 	}
 
+	// NOTE: .CpuQuota and .CpuPeriod are not used here. Conversion is the caller's responsibility.
 	if cgroup.Resources.CpuMax != "" {
 		if err := fscommon.WriteFile(dirPath, "cpu.max", cgroup.Resources.CpuMax); err != nil {
 			return err

libcontainer/cgroups/utils.go

@@ -609,3 +609,18 @@ func ConvertCPUSharesToCgroupV2Value(cpuShares uint64) uint64 {
 	}
 	return (1 + ((cpuShares-2)*9999)/262142)
 }
+
+// ConvertCPUQuotaCPUPeriodToCgroupV2Value generates cpu.max string.
+func ConvertCPUQuotaCPUPeriodToCgroupV2Value(quota int64, period uint64) string {
+	if quota <= 0 && period == 0 {
+		return ""
+	}
+	if period == 0 {
+		// This default value is documented in https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html
+		period = 100000
+	}
+	if quota <= 0 {
+		return fmt.Sprintf("max %d", period)
+	}
+	return fmt.Sprintf("%d %d", quota, period)
+}

libcontainer/cgroups/utils_test.go

@@ -485,3 +485,48 @@ func TestConvertCPUSharesToCgroupV2Value(t *testing.T) {
 		}
 	}
 }
+
+func TestConvertCPUQuotaCPUPeriodToCgroupV2Value(t *testing.T) {
+	cases := []struct {
+		quota    int64
+		period   uint64
+		expected string
+	}{
+		{
+			quota:    0,
+			period:   0,
+			expected: "",
+		},
+		{
+			quota:    -1,
+			period:   0,
+			expected: "",
+		},
+		{
+			quota:    1000,
+			period:   5000,
+			expected: "1000 5000",
+		},
+		{
+			quota:    0,
+			period:   5000,
+			expected: "max 5000",
+		},
+		{
+			quota:    -1,
+			period:   5000,
+			expected: "max 5000",
+		},
+		{
+			quota:    1000,
+			period:   0,
+			expected: "1000 100000",
+		},
+	}
+	for _, c := range cases {
+		got := ConvertCPUQuotaCPUPeriodToCgroupV2Value(c.quota, c.period)
+		if got != c.expected {
+			t.Errorf("expected ConvertCPUQuotaCPUPeriodToCgroupV2Value(%d, %d) to be %s, got %s", c.quota, c.period, c.expected, got)
+		}
+	}
+}

libcontainer/specconv/spec_linux.go

@@ -492,6 +492,9 @@ func CreateCgroupConfig(opts *CreateOpts) (*configs.Cgroup, error) {
 			if r.CPU.Period != nil {
 				c.Resources.CpuPeriod = *r.CPU.Period
 			}
+			//CpuMax is used for cgroupv2 and should be converted
+			c.Resources.CpuMax = cgroups.ConvertCPUQuotaCPUPeriodToCgroupV2Value(c.Resources.CpuQuota, c.Resources.CpuPeriod)
+
 			if r.CPU.RealtimeRuntime != nil {
 				c.Resources.CpuRtRuntime = *r.CPU.RealtimeRuntime
 			}

update.go

@@ -257,6 +257,8 @@ other options are ignored.
 		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)
+		//CpuMax is used for cgroupv2 and should be converted
+		config.Cgroups.Resources.CpuMax = cgroups.ConvertCPUQuotaCPUPeriodToCgroupV2Value(*r.CPU.Quota, *r.CPU.Period)
 		config.Cgroups.Resources.CpuRtPeriod = *r.CPU.RealtimePeriod
 		config.Cgroups.Resources.CpuRtRuntime = *r.CPU.RealtimeRuntime
 		config.Cgroups.Resources.CpusetCpus = r.CPU.Cpus