app: add sample application

samples/Dockerfile

@@ -0,0 +1,11 @@
+FROM  golang:1.20 AS builder
+WORKDIR /go/src/github.com/opeshift/cluster-node-tuning-operator/samples/app
+COPY . .
+RUN mkdir build || true && go build -o build/sample-app ./app
+
+FROM registry.access.redhat.com/ubi9/ubi
+COPY --from=builder /go/src/github.com/opeshift/cluster-node-tuning-operator/samples/app/build/sample-app /bin/sample-app
+RUN dnf install -y https://dl.fedoraproject.org/pub/epel/epel-release-latest-9.noarch.rpm && \
+    dnf install -y htop procps && \
+    dnf clean all
+ENTRYPOINT ["/bin/sample-app"]

samples/app/main.go

@@ -0,0 +1,119 @@
+package main
+
+import (
+	"bytes"
+	"errors"
+	"os"
+	"runtime"
+	"strconv"
+	"strings"
+	"sync"
+	"syscall"
+	"time"
+
+	"golang.org/x/sys/unix"
+
+	"k8s.io/klog/v2"
+	"k8s.io/kubernetes/pkg/kubelet/cm/cpuset"
+
+	"github.com/openshift-kni/mixed-cpu-node-plugin/pkg/deviceplugin"
+)
+
+func main() {
+	klog.Infof("reading /sys/fs/cgroup/cpuset/cpuset.cpus to retrieve the accessible cpus")
+	out, err := os.ReadFile("/sys/fs/cgroup/cpuset/cpuset.cpus")
+	if err != nil {
+		klog.Fatal(err)
+	}
+	cgroupCPUs := strings.TrimSuffix(string(out), "\n")
+	completeSet, err := cpuset.Parse(cgroupCPUs)
+	if err != nil {
+		klog.Fatalf("failed to parse cpuset %q; %v", cgroupCPUs, err)
+	}
+	klog.Infof("/sys/fs/cgroup/cpuset/cpuset.cpus content: %s", cgroupCPUs)
+
+	klog.Infof("reading environment variable:%q to retrieve the shared cpus", deviceplugin.EnvVarName)
+	cpus, ok := os.LookupEnv(deviceplugin.EnvVarName)
+	if !ok {
+		klog.Fatalf("%q environment variable not set", deviceplugin.EnvVarName)
+	}
+	sharedSet, err := cpuset.Parse(cpus)
+	if err != nil {
+		klog.Fatalf("failed to parse cpuset %q; %v", cpus, err)
+	}
+	if sharedSet.IsEmpty() {
+		klog.Warning("no shared cpus are configured for this process")
+	}
+	klog.Infof("%s=%s", deviceplugin.EnvVarName, cpus)
+	// here we extract the shared cpus from the complete set and find the isolated set
+	isolatedSet := completeSet.Difference(sharedSet)
+	klog.Infof("container finalized cpuset layout:\ncomplete-set=%q\nisolated-set=%q\nshared-set=%q", completeSet.String(), isolatedSet.String(), sharedSet.String())
+	var wg sync.WaitGroup
+	spawnLightWeightTasks(&sharedSet, &wg, 2)
+	spawnHeavyWeightTasks(&isolatedSet, &wg, 2)
+	wg.Wait()
+}
+
+func spawnLightWeightTasks(set *cpuset.CPUSet, wg *sync.WaitGroup, tasks int) {
+	for i := 0; i < tasks; i++ {
+		spawnTask(set, wg, "light weight task")
+	}
+}
+
+func spawnHeavyWeightTasks(set *cpuset.CPUSet, wg *sync.WaitGroup, tasks int) {
+	for i := 0; i < tasks; i++ {
+		spawnTask(set, wg, "heavy weight task")
+	}
+}
+
+func spawnTask(set *cpuset.CPUSet, wg *sync.WaitGroup, desc string) {
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		runtime.LockOSThread()
+		unixSet := k8sCPUstoUnixCPUs(set)
+		tid := syscall.Gettid()
+		id, err := goid()
+		if err != nil {
+			klog.Fatal(err)
+		}
+		if err := unix.SchedSetaffinity(0, unixSet); err != nil {
+			klog.Fatal(err)
+		}
+		for {
+			klog.Infof("%s: thread id %d => goroutine id: %d set affinity to cores: %q", desc, tid, id, set.String())
+			time.Sleep(60 * time.Second)
+		}
+	}()
+}
+
+func k8sCPUstoUnixCPUs(set *cpuset.CPUSet) *unix.CPUSet {
+	unixSet := &unix.CPUSet{}
+	for _, i := range set.List() {
+		unixSet.Set(i)
+	}
+	return unixSet
+}
+
+var (
+	goroutinePrefix = []byte("goroutine ")
+	errBadStack     = errors.New("invalid runtime.Stack output")
+)
+
+// This is terrible, slow, and should never be used in production.
+func goid() (int, error) {
+	buf := make([]byte, 32)
+	n := runtime.Stack(buf, false)
+	buf = buf[:n]
+	// goroutine 1 [running]: ...
+	buf, ok := bytes.CutPrefix(buf, goroutinePrefix)
+	if !ok {
+		return 0, errBadStack
+	}
+
+	i := bytes.IndexByte(buf, ' ')
+	if i < 0 {
+		return 0, errBadStack
+	}
+	return strconv.Atoi(string(buf[:i]))
+}

samples/go.mod

@@ -0,0 +1,63 @@
+module app
+
+go 1.20
+
+replace (
+	k8s.io/api => k8s.io/api v0.27.1
+	k8s.io/apiserver => k8s.io/apiserver v0.27.1
+	k8s.io/cli-runtime => k8s.io/cli-runtime v0.27.1
+	k8s.io/client-go => k8s.io/client-go v0.27.1
+	k8s.io/cloud-provider => k8s.io/cloud-provider v0.27.1
+	k8s.io/cluster-bootstrap => k8s.io/cluster-bootstrap v0.27.1
+	k8s.io/code-generator => k8s.io/code-generator v0.27.1
+	k8s.io/component-base => k8s.io/component-base v0.27.1
+	k8s.io/component-helpers => k8s.io/component-helpers v0.27.1
+	k8s.io/controller-manager => k8s.io/controller-manager v0.27.1
+	k8s.io/csi-translation-lib => k8s.io/csi-translation-lib v0.27.1
+	k8s.io/dynamic-resource-allocation => k8s.io/dynamic-resource-allocation v0.27.1
+	k8s.io/kms => k8s.io/kms v0.27.1
+	k8s.io/kube-aggregator => k8s.io/kube-aggregator v0.27.1
+	k8s.io/kube-controller-manager => k8s.io/kube-controller-manager v0.27.1
+	k8s.io/kube-proxy => k8s.io/kube-proxy v0.27.1
+	k8s.io/kube-scheduler => k8s.io/kube-scheduler v0.27.1
+	k8s.io/kubectl => k8s.io/kubectl v0.27.1
+	k8s.io/kubelet => k8s.io/kubelet v0.27.1
+	k8s.io/kubernetes => k8s.io/kubernetes v1.27.1
+	k8s.io/legacy-cloud-providers => k8s.io/legacy-cloud-providers v0.27.1
+	k8s.io/metrics => k8s.io/metrics v0.27.1
+	k8s.io/mount-utils => k8s.io/mount-utils v0.27.1
+	k8s.io/pod-security-admission => k8s.io/pod-security-admission v0.27.1
+	k8s.io/sample-apiserver => k8s.io/sample-apiserver v0.27.1
+)
+
+require (
+	github.com/containerd/cgroups v1.1.0
+	github.com/openshift-kni/mixed-cpu-node-plugin v0.0.0-20230814112512-f1a527d0a451
+	k8s.io/klog/v2 v2.100.1
+	k8s.io/kubernetes v1.25.4
+)
+
+require (
+	github.com/containerd/nri v0.2.0 // indirect
+	github.com/containerd/ttrpc v1.1.1-0.20220420014843-944ef4a40df3 // indirect
+	github.com/containers/podman/v4 v4.4.2 // indirect
+	github.com/coreos/go-systemd/v22 v22.5.0 // indirect
+	github.com/docker/go-units v0.5.0 // indirect
+	github.com/fsnotify/fsnotify v1.6.0 // indirect
+	github.com/go-logr/logr v1.2.3 // indirect
+	github.com/godbus/dbus/v5 v5.1.1-0.20221029134443-4b691ce883d5 // indirect
+	github.com/gogo/protobuf v1.3.2 // indirect
+	github.com/golang/glog v1.0.0 // indirect
+	github.com/golang/protobuf v1.5.3 // indirect
+	github.com/kubevirt/device-plugin-manager v1.19.4 // indirect
+	github.com/opencontainers/runtime-spec v1.0.3-0.20220909204839-494a5a6aca78 // indirect
+	github.com/sirupsen/logrus v1.9.0 // indirect
+	golang.org/x/net v0.8.0 // indirect
+	golang.org/x/sys v0.6.0 // indirect
+	golang.org/x/text v0.8.0 // indirect
+	google.golang.org/genproto v0.0.0-20221227171554-f9683d7f8bef // indirect
+	google.golang.org/grpc v1.51.0 // indirect
+	google.golang.org/protobuf v1.28.1 // indirect
+	k8s.io/cri-api v0.25.3 // indirect
+	k8s.io/kubelet v0.26.0 // indirect
+)