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only configure swap if swap is enabled #120784

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merged 2 commits into from
Sep 27, 2023
Merged

only configure swap if swap is enabled #120784

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d3d1827
Use local isCgroup2UnifiedMode consistently
elezar Sep 21, 2023
394bcaf
Only configure swap if available on node
elezar Sep 21, 2023
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45 changes: 31 additions & 14 deletions pkg/kubelet/kuberuntime/kuberuntime_container_linux.go
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Original file line number Diff line number Diff line change
Expand Up @@ -107,18 +107,8 @@ func (m *kubeGenericRuntimeManager) generateLinuxContainerResources(pod *v1.Pod,

lcr.HugepageLimits = GetHugepageLimitsFromResources(container.Resources)

if swapConfigurationHelper := newSwapConfigurationHelper(*m.machineInfo); utilfeature.DefaultFeatureGate.Enabled(kubefeatures.NodeSwap) {
// NOTE(ehashman): Behaviour is defined in the opencontainers runtime spec:
// https://github.com/opencontainers/runtime-spec/blob/1c3f411f041711bbeecf35ff7e93461ea6789220/config-linux.md#memory
switch m.memorySwapBehavior {
case kubelettypes.LimitedSwap:
swapConfigurationHelper.ConfigureLimitedSwap(lcr, pod, container)
default:
swapConfigurationHelper.ConfigureUnlimitedSwap(lcr)
}
} else {
swapConfigurationHelper.ConfigureNoSwap(lcr)
}
// Configure swap for the container
m.configureContainerSwapResources(lcr, pod, container)

// Set memory.min and memory.high to enforce MemoryQoS
if enforceMemoryQoS {
Expand Down Expand Up @@ -170,6 +160,30 @@ func (m *kubeGenericRuntimeManager) generateLinuxContainerResources(pod *v1.Pod,
return lcr
}

// configureContainerSwapResources configures the swap resources for a specified (linux) container.
// Swap is only configured if a swap cgroup controller is available and the NodeSwap feature gate is enabled.
func (m *kubeGenericRuntimeManager) configureContainerSwapResources(lcr *runtimeapi.LinuxContainerResources, pod *v1.Pod, container *v1.Container) {
if !swapControllerAvailable() {
klog.InfoS("No swap cgroup controller present", "swapBehavior", m.memorySwapBehavior, "pod", klog.KObj(pod), "containerName", container.Name)
return
}
swapConfigurationHelper := newSwapConfigurationHelper(*m.machineInfo)

if !utilfeature.DefaultFeatureGate.Enabled(kubefeatures.NodeSwap) {
swapConfigurationHelper.ConfigureNoSwap(lcr)
return
}

// NOTE(ehashman): Behavior is defined in the opencontainers runtime spec:
// https://github.com/opencontainers/runtime-spec/blob/1c3f411f041711bbeecf35ff7e93461ea6789220/config-linux.md#memory
switch m.memorySwapBehavior {
case kubelettypes.LimitedSwap:
swapConfigurationHelper.ConfigureLimitedSwap(lcr, pod, container)
default:
swapConfigurationHelper.ConfigureUnlimitedSwap(lcr)
}
}

// generateContainerResources generates platform specific (linux) container resources config for runtime
func (m *kubeGenericRuntimeManager) generateContainerResources(pod *v1.Pod, container *v1.Container) *runtimeapi.ContainerResources {
enforceMemoryQoS := false
Expand Down Expand Up @@ -315,12 +329,15 @@ var (
swapControllerAvailabilityOnce sync.Once
)

func swapControllerAvailable() bool {
// Note: this function variable is being added here so it would be possible to mock
// the swap controller availability for unit tests by assigning a new function to it. Without it,
// the swap controller availability would solely depend on the environment running the test.
var swapControllerAvailable = func() bool {
// See https://github.com/containerd/containerd/pull/7838/
swapControllerAvailabilityOnce.Do(func() {
const warn = "Failed to detect the availability of the swap controller, assuming not available"
p := "/sys/fs/cgroup/memory/memory.memsw.limit_in_bytes"
if libcontainercgroups.IsCgroup2UnifiedMode() {
if isCgroup2UnifiedMode() {
Comment on lines -323 to +340
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👍!

// memory.swap.max does not exist in the cgroup root, so we check /sys/fs/cgroup/<SELF>/memory.swap.max
_, unified, err := cgroups.ParseCgroupFileUnified("/proc/self/cgroup")
if err != nil {
Expand Down