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clarify cpu.cfs_period_us default value

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cpu.cfs_period_us is 100μs by default despite having an "ms" unit
for some unfortunate reason. Documentation:
https://www.kernel.org/doc/html/latest/scheduler/sched-bwc.html#management

The desired effect of that change is more clarity on the default value
so users would be aware that the 10ms custom value would be
not 0.1x of the default, but 100x of it.
This commit is contained in:
Dmitry Verkhoturov 2022-07-29 23:02:35 +02:00
parent c06031959f
commit 5126192548
5 changed files with 11 additions and 11 deletions
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2
pkg/kubelet/apis/config/scheme/testdata/KubeletConfiguration/after/v1beta1.yaml vendored
View File

@ -19,7 +19,7 @@ containerLogMaxFiles: 5
containerLogMaxSize: 10Mi
contentType: application/vnd.kubernetes.protobuf
cpuCFSQuota: true
cpuCFSQuotaPeriod: 100ms
cpuCFSQuotaPeriod: 100us
cpuManagerPolicy: none
cpuManagerReconcilePeriod: 10s
enableControllerAttachDetach: true

2
pkg/kubelet/apis/config/scheme/testdata/KubeletConfiguration/roundtrip/default/v1beta1.yaml vendored
View File

@ -19,7 +19,7 @@ containerLogMaxFiles: 5
containerLogMaxSize: 10Mi
contentType: application/vnd.kubernetes.protobuf
cpuCFSQuota: true
cpuCFSQuotaPeriod: 100ms
cpuCFSQuotaPeriod: 100us
cpuManagerPolicy: none
cpuManagerReconcilePeriod: 10s
enableControllerAttachDetach: true

6
pkg/kubelet/apis/config/validation/validation_test.go
View File

@ -58,7 +58,7 @@ var (
RegistryPullQPS: 5,
HairpinMode: kubeletconfig.PromiscuousBridge,
NodeLeaseDurationSeconds: 1,
CPUCFSQuotaPeriod: metav1.Duration{Duration: 25 * time.Millisecond},
CPUCFSQuotaPeriod: metav1.Duration{Duration: 25 * time.Microsecond},
TopologyManagerScope: kubeletconfig.PodTopologyManagerScope,
TopologyManagerPolicy: kubeletconfig.SingleNumaNodeTopologyManagerPolicy,
ShutdownGracePeriod: metav1.Duration{Duration: 30 * time.Second},
@ -144,10 +144,10 @@ func TestValidateKubeletConfiguration(t *testing.T) {
name: "specify CPUCFSQuotaPeriod without enabling CPUCFSQuotaPeriod",
configure: func(conf *kubeletconfig.KubeletConfiguration) *kubeletconfig.KubeletConfiguration {
conf.FeatureGates = map[string]bool{"CustomCPUCFSQuotaPeriod": false}
conf.CPUCFSQuotaPeriod = metav1.Duration{Duration: 200 * time.Millisecond}
conf.CPUCFSQuotaPeriod = metav1.Duration{Duration: 200 * time.Microsecond}
return conf
},
errMsg: "invalid configuration: cpuCFSQuotaPeriod (--cpu-cfs-quota-period) {200ms} requires feature gate CustomCPUCFSQuotaPeriod",
errMsg: "invalid configuration: cpuCFSQuotaPeriod (--cpu-cfs-quota-period) {200us} requires feature gate CustomCPUCFSQuotaPeriod",
},
{
name: "invalid CPUCFSQuotaPeriod",

6
pkg/kubelet/cm/helpers_linux.go
View File

@ -44,7 +44,7 @@ const (
SharesPerCPU = 1024
MilliCPUToCPU = 1000
// 100000 is equivalent to 100ms
// 100000 is equivalent to 100usec
QuotaPeriod = 100000
MinQuotaPeriod = 1000
)
@ -52,8 +52,8 @@ const (
// MilliCPUToQuota converts milliCPU to CFS quota and period values.
func MilliCPUToQuota(milliCPU int64, period int64) (quota int64) {
// CFS quota is measured in two values:
// - cfs_period_us=100ms (the amount of time to measure usage across given by period)
// - cfs_quota=20ms (the amount of cpu time allowed to be used across a period)
// - cfs_period_us=100usec (the amount of time to measure usage across given by period)
// - cfs_quota=20usec (the amount of cpu time allowed to be used across a period)
// so in the above example, you are limited to 20% of a single CPU
// for multi-cpu environments, you just scale equivalent amounts
// see https://www.kernel.org/doc/Documentation/scheduler/sched-bwc.txt for details

6
pkg/kubelet/kuberuntime/helpers_linux.go
View File

@ -22,7 +22,7 @@ package kuberuntime
const (
milliCPUToCPU = 1000
// 100000 is equivalent to 100ms
// 100000 is equivalent to 100usec
quotaPeriod = 100000
minQuotaPeriod = 1000
)
@ -30,8 +30,8 @@ const (
// milliCPUToQuota converts milliCPU to CFS quota and period values
func milliCPUToQuota(milliCPU int64, period int64) (quota int64) {
// CFS quota is measured in two values:
// - cfs_period_us=100ms (the amount of time to measure usage across)
// - cfs_quota=20ms (the amount of cpu time allowed to be used across a period)
// - cfs_period_us=100usec (the amount of time to measure usage across given by period)
// - cfs_quota=20usec (the amount of cpu time allowed to be used across a period)
// so in the above example, you are limited to 20% of a single CPU
// for multi-cpu environments, you just scale equivalent amounts
// see https://www.kernel.org/doc/Documentation/scheduler/sched-bwc.txt for details