112 lines
4.6 KiB
Diff
112 lines
4.6 KiB
Diff
From 7bae7fe0f023b4c6a49910bf583af7ccc4af9391 Mon Sep 17 00:00:00 2001
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From: Jim Gauld <james.gauld@windriver.com>
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Date: Thu, 5 Sep 2019 10:46:58 -0400
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Subject: [PATCH 1/6] kubelet cpumanager disable CFS quota throttling for
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Guaranteed pods
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This disables CFS CPU quota to avoid performance degradation due to
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Linux kernel CFS quota implementation. Note that 4.18 kernel attempts
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to solve the CFS throttling problem, but there are reports that it is
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not completely effective.
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This disables CFS quota throttling for Guaranteed pods for both
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parent and container cgroups by writing -1 to cgroup cpu.cfs_quota_us.
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Disabling has a dramatic latency improvement for HTTP response times.
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Signed-off-by: Jim Gauld <james.gauld@windriver.com>
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---
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pkg/kubelet/cm/cpumanager/cpu_manager.go | 22 ++++++++++++++++++++++
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pkg/kubelet/cm/helpers_linux.go | 5 +++++
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pkg/kubelet/cm/helpers_linux_test.go | 8 ++++----
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3 files changed, 31 insertions(+), 4 deletions(-)
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diff --git a/pkg/kubelet/cm/cpumanager/cpu_manager.go b/pkg/kubelet/cm/cpumanager/cpu_manager.go
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index 07ff3d9c860..fc3a247e70b 100644
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--- a/pkg/kubelet/cm/cpumanager/cpu_manager.go
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+++ b/pkg/kubelet/cm/cpumanager/cpu_manager.go
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@@ -36,6 +36,7 @@ import (
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"k8s.io/kubernetes/pkg/kubelet/config"
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kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
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"k8s.io/kubernetes/pkg/kubelet/status"
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+ v1qos "k8s.io/kubernetes/pkg/apis/core/v1/helper/qos"
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)
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// ActivePodsFunc is a function that returns a list of pods to reconcile.
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@@ -233,6 +234,14 @@ func (m *manager) AddContainer(p *v1.Pod, c *v1.Container, containerID string) e
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// Get the CPUs assigned to the container during Allocate()
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// (or fall back to the default CPUSet if none were assigned).
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cpus := m.state.GetCPUSetOrDefault(string(p.UID), c.Name)
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+
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+ // Guaranteed PODs should not have CFS quota throttle
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+ if m.policy.Name() == string(PolicyStatic) && v1qos.GetPodQOS(p) == v1.PodQOSGuaranteed {
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+ err := m.disableContainerCPUQuota(containerID)
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+ if err != nil {
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+ klog.Errorf("[cpumanager] AddContainer disable CPU Quota error: %v", err)
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+ }
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+ }
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m.Unlock()
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if !cpus.IsEmpty() {
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@@ -464,3 +473,16 @@ func (m *manager) updateContainerCPUSet(containerID string, cpus cpuset.CPUSet)
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CpusetCpus: cpus.String(),
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})
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}
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+
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+func (m *manager) disableContainerCPUQuota(containerID string) error {
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+ // Disable CFS CPU quota to avoid performance degradation due to
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+ // Linux kernel CFS throttle implementation.
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+ // NOTE: 4.18 kernel attempts to solve CFS throttling problem,
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+ // but there are reports that it is not completely effective.
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+ return m.containerRuntime.UpdateContainerResources(
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+ containerID,
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+ &runtimeapi.LinuxContainerResources{
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+ CpuPeriod: 100000,
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+ CpuQuota: -1,
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+ })
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+}
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diff --git a/pkg/kubelet/cm/helpers_linux.go b/pkg/kubelet/cm/helpers_linux.go
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index 9b115ab5380..d3185e1e958 100644
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--- a/pkg/kubelet/cm/helpers_linux.go
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+++ b/pkg/kubelet/cm/helpers_linux.go
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@@ -166,6 +166,11 @@ func ResourceConfigForPod(pod *v1.Pod, enforceCPULimits bool, cpuPeriod uint64)
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// determine the qos class
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qosClass := v1qos.GetPodQOS(pod)
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+ // disable cfs quota for guaranteed pods
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+ if qosClass == v1.PodQOSGuaranteed {
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+ cpuQuota = int64(-1)
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+ }
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+
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// build the result
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result := &ResourceConfig{}
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if qosClass == v1.PodQOSGuaranteed {
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diff --git a/pkg/kubelet/cm/helpers_linux_test.go b/pkg/kubelet/cm/helpers_linux_test.go
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index 56d765fbc22..0c43afe5875 100644
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--- a/pkg/kubelet/cm/helpers_linux_test.go
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+++ b/pkg/kubelet/cm/helpers_linux_test.go
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@@ -63,8 +63,8 @@ func TestResourceConfigForPod(t *testing.T) {
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burstablePartialShares := MilliCPUToShares(200)
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burstableQuota := MilliCPUToQuota(200, int64(defaultQuotaPeriod))
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guaranteedShares := MilliCPUToShares(100)
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- guaranteedQuota := MilliCPUToQuota(100, int64(defaultQuotaPeriod))
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- guaranteedTunedQuota := MilliCPUToQuota(100, int64(tunedQuotaPeriod))
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+ guaranteedQuota := int64(-1)
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+ guaranteedTunedQuota := int64(-1)
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memoryQuantity = resource.MustParse("100Mi")
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cpuNoLimit := int64(-1)
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guaranteedMemory := memoryQuantity.Value()
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@@ -283,8 +283,8 @@ func TestResourceConfigForPodWithCustomCPUCFSQuotaPeriod(t *testing.T) {
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burstablePartialShares := MilliCPUToShares(200)
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burstableQuota := MilliCPUToQuota(200, int64(defaultQuotaPeriod))
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guaranteedShares := MilliCPUToShares(100)
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- guaranteedQuota := MilliCPUToQuota(100, int64(defaultQuotaPeriod))
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- guaranteedTunedQuota := MilliCPUToQuota(100, int64(tunedQuotaPeriod))
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+ guaranteedQuota := int64(-1)
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+ guaranteedTunedQuota := int64(-1)
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memoryQuantity = resource.MustParse("100Mi")
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cpuNoLimit := int64(-1)
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guaranteedMemory := memoryQuantity.Value()
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--
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2.24.2
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