UPSTREAM: <carry>: advertise shared cpus for mixed cpus feature

Kubelet should advertise the shared cpus as extedned resources.
This has the benefit of limiting the amount of containers
that can request an access to the shared cpus.

For more information see - openshift/enhancements#1396

Signed-off-by: Talor Itzhak <[email protected]>

Author: Tal-or

pkg/kubelet/kubelet.go

@@ -113,6 +113,7 @@ import (
 	"k8s.io/kubernetes/pkg/kubelet/server"
 	servermetrics "k8s.io/kubernetes/pkg/kubelet/server/metrics"
 	serverstats "k8s.io/kubernetes/pkg/kubelet/server/stats"
+	"k8s.io/kubernetes/pkg/kubelet/sharedcpus"
 	"k8s.io/kubernetes/pkg/kubelet/stats"
 	"k8s.io/kubernetes/pkg/kubelet/status"
 	"k8s.io/kubernetes/pkg/kubelet/sysctl"
@@ -681,6 +682,9 @@ func NewMainKubelet(kubeCfg *kubeletconfiginternal.KubeletConfiguration,
 	if managed.IsEnabled() {
 		klog.InfoS("Pinned Workload Management Enabled")
 	}
+	if sharedcpus.IsEnabled() {
+		klog.InfoS("Mixed CPUs Workload Enabled")
+	}
 
 	if kubeDeps.KubeClient != nil {
 		klet.runtimeClassManager = runtimeclass.NewManager(kubeDeps.KubeClient)

pkg/kubelet/kubelet_node_status.go

@@ -46,6 +46,7 @@ import (
 	"k8s.io/kubernetes/pkg/kubelet/events"
 	"k8s.io/kubernetes/pkg/kubelet/managed"
 	"k8s.io/kubernetes/pkg/kubelet/nodestatus"
+	"k8s.io/kubernetes/pkg/kubelet/sharedcpus"
 	taintutil "k8s.io/kubernetes/pkg/util/taints"
 	volutil "k8s.io/kubernetes/pkg/volume/util"
 )
@@ -136,6 +137,7 @@ func (kl *Kubelet) tryRegisterWithAPIServer(node *v1.Node) bool {
 	if managed.IsEnabled() {
 		requiresUpdate = kl.addManagementNodeCapacity(node, existingNode) || requiresUpdate
 	}
+	requiresUpdate = kl.reconcileSharedCPUsNodeCapacity(node, existingNode) || requiresUpdate
 	if requiresUpdate {
 		if _, _, err := nodeutil.PatchNodeStatus(kl.kubeClient.CoreV1(), types.NodeName(kl.nodeName), originalNode, existingNode); err != nil {
 			klog.ErrorS(err, "Unable to reconcile node with API server,error updating node", "node", klog.KObj(node))
@@ -165,6 +167,25 @@ func (kl *Kubelet) addManagementNodeCapacity(initialNode, existingNode *v1.Node)
 	return true
 }
 
+func (kl *Kubelet) reconcileSharedCPUsNodeCapacity(initialNode, existingNode *v1.Node) bool {
+	updateDefaultResources(initialNode, existingNode)
+	sharedCPUsResourceName := sharedcpus.GetResourceName()
+	// delete resources in case they exist and feature has been disabled
+	if !sharedcpus.IsEnabled() {
+		if _, ok := existingNode.Status.Capacity[sharedCPUsResourceName]; ok {
+			delete(existingNode.Status.Capacity, sharedCPUsResourceName)
+			return true
+		}
+		return false
+	}
+	q := resource.NewQuantity(sharedcpus.GetConfig().ContainersLimit, resource.DecimalSI)
+	if existingCapacity, ok := existingNode.Status.Capacity[sharedCPUsResourceName]; ok && existingCapacity.Equal(*q) {
+		return false
+	}
+	existingNode.Status.Capacity[sharedCPUsResourceName] = *q
+	return true
+}
+
 // reconcileHugePageResource will update huge page capacity for each page size and remove huge page sizes no longer supported
 func (kl *Kubelet) reconcileHugePageResource(initialNode, existingNode *v1.Node) bool {
 	requiresUpdate := updateDefaultResources(initialNode, existingNode)
@@ -459,6 +480,7 @@ func (kl *Kubelet) initialNode(ctx context.Context) (*v1.Node, error) {
 	if managed.IsEnabled() {
 		kl.addManagementNodeCapacity(node, node)
 	}
+	kl.reconcileSharedCPUsNodeCapacity(node, node)
 
 	kl.setNodeStatus(ctx, node)
 

pkg/kubelet/sharedcpus/sharedcpus.go

@@ -0,0 +1,87 @@
+/*
+Copyright 2023 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package sharedcpus
+
+import (
+	"encoding/json"
+	"errors"
+	"os"
+
+	corev1 "k8s.io/api/core/v1"
+	"k8s.io/klog/v2"
+)
+
+const (
+	configFileName         = "/etc/kubernetes/openshift-workload-mixed-cpus"
+	sharedCpusResourceName = "workload.openshift.io/enable-shared-cpus"
+)
+
+var (
+	config            Config
+	sharedCpusEnabled bool
+)
+
+type Config struct {
+	sharedCpus `json:"shared_cpus"`
+}
+
+type sharedCpus struct {
+	// ContainersLimit specify the number of containers that are allowed to access the shared CPU pool`
+	ContainersLimit int64 `json:"containers_limit"`
+}
+
+func init() {
+	parseConfig()
+}
+
+func IsEnabled() bool {
+	return sharedCpusEnabled
+}
+
+func GetResourceName() corev1.ResourceName {
+	return sharedCpusResourceName
+}
+
+func GetConfig() Config {
+	return config
+}
+
+func parseConfig() {
+	b, err := os.ReadFile(configFileName)
+	if err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			return
+		}
+		klog.ErrorS(err, "Failed to read configuration file for shared cpus", "fileName", configFileName)
+		return
+	}
+	cfg, err := parseConfigData(b)
+	if err != nil {
+		return
+	}
+	config = *cfg
+	sharedCpusEnabled = true
+}
+
+func parseConfigData(data []byte) (*Config, error) {
+	cfg := &Config{}
+	err := json.Unmarshal(data, cfg)
+	if err != nil {
+		klog.ErrorS(err, "Failed to parse configuration file for shared cpus", "fileContent", string(data))
+	}
+	return cfg, err
+}

pkg/kubelet/sharedcpus/sharedcpus_test.go

@@ -0,0 +1,39 @@
+package sharedcpus
+
+import "testing"
+
+func TestParseConfigData(t *testing.T) {
+	testCases := []struct {
+		data                []byte
+		expectedToBeParsed  bool
+		containerLimitValue int64
+	}{
+		{
+			data: []byte(`{
+					"shared_cpus": {
+     					"containers_limit": 15
+					}
+				}`),
+			expectedToBeParsed:  true,
+			containerLimitValue: 15,
+		},
+		{
+			data: []byte(`{
+					"shared_cpus": {
+     					"abc": "25"
+  					}
+				}`),
+			expectedToBeParsed:  false,
+			containerLimitValue: 0,
+		},
+	}
+	for _, tc := range testCases {
+		cfg, err := parseConfigData(tc.data)
+		if err != nil && tc.expectedToBeParsed {
+			t.Errorf("shared cpus data expected to be parsed")
+		}
+		if cfg.ContainersLimit != tc.containerLimitValue {
+			t.Errorf("shared cpus ContainersLimit is different than expected: want: %d; got %d", tc.containerLimitValue, cfg.ContainersLimit)
+		}
+	}
+}