Allow to specify a cpu pressure usage value

api/v1beta1/cpu_pressure.go

@@ -5,13 +5,28 @@
 
 package v1beta1
 
+import (
+	"github.com/hashicorp/go-multierror"
+	"k8s.io/apimachinery/pkg/util/intstr"
+)
+
 // CPUPressureSpec represents a cpu pressure disruption
 type CPUPressureSpec struct {
+	Count *intstr.IntOrString `json:"count,omitempty"` // number of cores to target, either an integer form or a percentage form appended with a %
 }
 
 // Validate validates args for the given disruption
-func (s *CPUPressureSpec) Validate() error {
-	return nil
+func (s *CPUPressureSpec) Validate() (retErr error) {
+	if s.Count == nil {
+		return nil
+	}
+
+	// Rule: count must be valid
+	if err := ValidateCount(s.Count); err != nil {
+		retErr = multierror.Append(retErr, err)
+	}
+
+	return retErr
 }
 
 // GenerateArgs generates injection or cleanup pod arguments for the given spec
@@ -20,5 +35,9 @@ func (s *CPUPressureSpec) GenerateArgs() []string {
 		"cpu-pressure",
 	}
 
+	if s.Count != nil {
+		args = append(args, []string{"--count", s.Count.String()}...)
+	}
+
 	return args
 }

chart/templates/crds/chaos.datadoghq.com_disruptions.yaml

@@ -85,6 +85,12 @@ spec:
               cpuPressure:
                 description: CPUPressureSpec represents a cpu pressure disruption
                 nullable: true
+                properties:
+                  count:
+                    anyOf:
+                    - type: integer
+                    - type: string
+                    x-kubernetes-int-or-string: true
                 type: object
               diskPressure:
                 description: DiskPressureSpec represents a disk pressure disruption

cli/injector/cpu_pressure.go

@@ -10,17 +10,23 @@ import (
 	"github.com/DataDog/chaos-controller/injector"
 	"github.com/DataDog/chaos-controller/stress"
 	"github.com/spf13/cobra"
+	"k8s.io/apimachinery/pkg/util/intstr"
 )
 
 var cpuPressureCmd = &cobra.Command{
 	Use:   "cpu-pressure",
 	Short: "CPU pressure subcommands",
 	Run:   injectAndWait,
 	PreRun: func(cmd *cobra.Command, args []string) {
+		countStr, _ := cmd.Flags().GetString("count")
+		count := intstr.FromString(countStr)
+
 		// prepare spec
-		spec := v1beta1.CPUPressureSpec{}
-		stresserManager := stress.NewCPUStresserManager(log)
+		spec := v1beta1.CPUPressureSpec{
+			Count: &count,
+		}
 
+		stresserManager := stress.NewCPUStresserManager(log)
 		// create injector
 		for _, config := range configs {
 			injector, _ := injector.NewCPUPressureInjector(spec, injector.CPUPressureInjectorConfig{
@@ -31,3 +37,7 @@ var cpuPressureCmd = &cobra.Command{
 		}
 	},
 }
+
+func init() {
+	cpuPressureCmd.Flags().String("count", "", "number of cores to target, either an integer form or a percentage form appended with a %")
+}

docs/cpu_pressure.md

@@ -21,7 +21,9 @@ The `/sys/fs/cgroup` directory of the host must be mounted in the injector pod a
 When the injector pod starts:
 
 - It parses the `cpuset.cpus` file (located in the target `cpuset` cgroup) to retrieve cores allocated to the target processes.
-- It creates one goroutine per allocated core. Each goroutine is locked on the thread they are running on. By doing so, it forces the Go runtime scheduler to create one thread per locked goroutine.
+- It calculates the number of cores to apply pressure, by taking user input `Count`.
+- It then creates one goroutine per target core.
+- Each goroutine is locked on the thread they are running on. By doing so, it forces the Go runtime scheduler to create one thread per locked goroutine.
 - Each goroutine joins the target `cpu` and `cpuset` cgroups.
   - Joining the `cpuset` cgroup is important to both have the same number of allocated cores as the target as well as the same allocated cores so we ensure that the goroutines threads will be scheduled on the same cores as the target processes
 - Each goroutine renices itself to the highest priority (`-20`) so the Linux scheduler will always give it the priority to consume CPU time over other running processes

examples/cpu_pressure.yaml

@@ -13,4 +13,5 @@ spec:
   selector:
     app: demo-curl
   count: 1
-  cpuPressure: {} # consume as much CPU as possible to generate load
+  cpuPressure:
+    count: 50%

injector/cpu_pressure.go

@@ -62,7 +62,7 @@ func (i *cpuPressureInjector) GetDisruptionKind() types.DisruptionKindName {
 }
 
 func (i *cpuPressureInjector) Inject() error {
-	cores, err := i.config.StresserManager.TrackInjectorCores(i.config.Cgroup)
+	cores, err := i.config.StresserManager.TrackInjectorCores(i.config.Cgroup, i.spec.Count)
 
 	if err != nil {
 		return fmt.Errorf("failed to parse CPUSet %w", err)

injector/cpu_pressure_test.go

@@ -15,6 +15,7 @@ import (
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
 	"github.com/stretchr/testify/mock"
+	"k8s.io/apimachinery/pkg/util/intstr"
 )
 
 var _ = Describe("Failure", func() {
@@ -51,7 +52,6 @@ var _ = Describe("Failure", func() {
 		manager.On("ThreadID").Return(666)
 
 		stresserManager = &stress.StresserManagerMock{}
-		stresserManager.On("TrackInjectorCores", mock.Anything).Return(cpuset.NewCPUSet(0, 1), nil)
 		stresserManager.On("TrackCoreAlreadyStressed", mock.Anything, mock.Anything).Return(nil)
 		stresserManager.On("StresserPIDs").Return(map[int]int{0: 666})
 		stresserManager.On("IsCoreAlreadyStressed", 0).Return(true)
@@ -73,7 +73,9 @@ var _ = Describe("Failure", func() {
 
 		// spec
 		spec = v1beta1.CPUPressureSpec{}
+	})
 
+	JustBeforeEach(func() {
 		var err error
 		inj, err = NewCPUPressureInjector(spec, config)
 		Expect(err).To(BeNil())
@@ -98,27 +100,46 @@ var _ = Describe("Failure", func() {
 	})
 
 	Describe("injection", func() {
-
-		It("should join the cpu and cpuset cgroups for the unstressed core", func() {
-			cgroupManager.AssertCalled(GinkgoT(), "Join", "cpu", 666, false)
-			cgroupManager.AssertCalled(GinkgoT(), "Join", "cpuset", 666, false)
-			cgroupManager.AssertNumberOfCalls(GinkgoT(), "Join", 2)
-		})
-
-		It("should prioritize the current process", func() {
-			manager.AssertCalled(GinkgoT(), "Prioritize")
-		})
-
-		It("should run the stress on one core", func() {
-			stresser.AssertNumberOfCalls(GinkgoT(), "Stress", 1)
-		})
-
-		It("should record core and StresserPID in StresserManager", func() {
-			stresserManager.AssertCalled(GinkgoT(), "TrackCoreAlreadyStressed", 1, 666)
+		Context("user request to stress all the cores", func() {
+			BeforeEach(func() {
+				stresserManager.On("TrackInjectorCores", mock.Anything, mock.Anything).Return(cpuset.NewCPUSet(0, 1), nil)
+			})
+
+			It("should join the cpu and cpuset cgroups for the unstressed core", func() {
+				cgroupManager.AssertCalled(GinkgoT(), "Join", "cpu", 666, false)
+				cgroupManager.AssertCalled(GinkgoT(), "Join", "cpuset", 666, false)
+				cgroupManager.AssertNumberOfCalls(GinkgoT(), "Join", 2)
+			})
+
+			It("should prioritize the current process", func() {
+				manager.AssertCalled(GinkgoT(), "Prioritize")
+			})
+
+			It("should run the stress on one core", func() {
+				stresser.AssertNumberOfCalls(GinkgoT(), "Stress", 1)
+			})
+
+			It("should record core and StresserPID in StresserManager", func() {
+				stresserManager.AssertCalled(GinkgoT(), "TrackCoreAlreadyStressed", 1, 666)
+			})
+
+			It("should skip a target core that was already stress", func() {
+				stresserManager.AssertNotCalled(GinkgoT(), "TrackCoreAlreadyStressed", 0, mock.Anything)
+			})
 		})
 
-		It("should skip a target core that was already stress", func() {
-			stresserManager.AssertNotCalled(GinkgoT(), "TrackCoreAlreadyStressed", 0, mock.Anything)
+		Context("user request to stress half of the cores", func() {
+			BeforeEach(func() {
+				userRequestCount := intstr.FromString("50%")
+				spec = v1beta1.CPUPressureSpec{
+					Count: &userRequestCount,
+				}
+				stresserManager.On("TrackInjectorCores", mock.Anything, &userRequestCount).Return(cpuset.NewCPUSet(0, 1), nil)
+			})
+
+			It("should call stresserManager track cores and get new core to apply pressure", func() {
+				// left empty for AfterEach
+			})
 		})
 	})
 })

stress/cpuset_manager.go

@@ -10,12 +10,13 @@ import (
 	"github.com/DataDog/chaos-controller/cgroup"
 	"github.com/DataDog/chaos-controller/cpuset"
 	"go.uber.org/zap"
+	"k8s.io/apimachinery/pkg/util/intstr"
 	"runtime"
 	"sync"
 )
 
 type StresserManager interface {
-	TrackInjectorCores(cgroup cgroup.Manager) (cpuset.CPUSet, error)
+	TrackInjectorCores(cgroup cgroup.Manager, userRequestCount *intstr.IntOrString) (cpuset.CPUSet, error)
 	IsCoreAlreadyStressed(core int) bool
 	TrackCoreAlreadyStressed(core int, stresserPID int)
 	StresserPIDs() map[int]int
@@ -63,7 +64,7 @@ func (manager *cpuStressserManager) StresserPIDs() map[int]int {
 	return manager.stresserPIDPerCore
 }
 
-func (manager *cpuStressserManager) TrackInjectorCores(cgroup cgroup.Manager) (cpuset.CPUSet, error) {
+func (manager *cpuStressserManager) TrackInjectorCores(cgroup cgroup.Manager, userRequestCount *intstr.IntOrString) (cpuset.CPUSet, error) {
 	// read cpuset allocated cores
 	manager.log.Infow("retrieving target cpuset allocated cores")
 
@@ -78,7 +79,11 @@ func (manager *cpuStressserManager) TrackInjectorCores(cgroup cgroup.Manager) (c
 		return cpuset.NewCPUSet(), fmt.Errorf("error parsing cpuset allocated cores: %w", err)
 	}
 
-	manager.setCoresToBeStressed(manager.coresToBeStressed.Union(cores))
+	coresToBeStressedCount, _ := intstr.GetScaledValueFromIntOrPercent(userRequestCount, cores.Size(), true)
+	coresToBeStressed := cpuset.NewCPUSet(cores.ToSlice()[:coresToBeStressedCount]...)
 
-	return cores, nil
+	manager.log.Infof("retrieved coresToBeStressed after applying userRequestCount %s: %s", userRequestCount.StrVal, coresToBeStressed)
+	manager.setCoresToBeStressed(manager.coresToBeStressed.Union(coresToBeStressed))
+
+	return coresToBeStressed, nil
 }

stress/cpuset_manager_mock.go

@@ -8,6 +8,7 @@ package stress
 import (
 	"github.com/DataDog/chaos-controller/cgroup"
 	"github.com/stretchr/testify/mock"
+	"k8s.io/apimachinery/pkg/util/intstr"
 )
 import (
 	"github.com/DataDog/chaos-controller/cpuset"
@@ -35,7 +36,7 @@ func (f *StresserManagerMock) StresserPIDs() map[int]int {
 }
 
 //nolint:golint
-func (f *StresserManagerMock) TrackInjectorCores(cgroup cgroup.Manager) (cpuset.CPUSet, error) {
-	args := f.Called(cgroup)
+func (f *StresserManagerMock) TrackInjectorCores(cgroup cgroup.Manager, userRequestCount *intstr.IntOrString) (cpuset.CPUSet, error) {
+	args := f.Called(cgroup, userRequestCount)
 	return args.Get(0).(cpuset.CPUSet), args.Error(1)
 }

stress/cpuset_manager_test.go

@@ -0,0 +1,95 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2022 Datadog, Inc.
+
+package stress_test
+
+import (
+	. "github.com/DataDog/chaos-controller/cgroup"
+	"github.com/DataDog/chaos-controller/cpuset"
+	. "github.com/DataDog/chaos-controller/stress"
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+	"go.uber.org/zap"
+	"k8s.io/apimachinery/pkg/util/intstr"
+)
+
+var _ = Describe("StresserManager Test", func() {
+	var (
+		log             *zap.SugaredLogger
+		stresserManager StresserManager
+	)
+
+	BeforeEach(func() {
+		z, _ := zap.NewDevelopment()
+		log = z.Sugar()
+		stresserManager = NewCPUStresserManager(log)
+	})
+
+	When("IsCoreAlreadyStress", func() {
+		Context("StresserManager is freshly initialized", func() {
+			It("does not have any core stressed", func() {
+				Expect(stresserManager.IsCoreAlreadyStressed(1)).To(BeFalse())
+				Expect(stresserManager.StresserPIDs()).To(BeEmpty())
+			})
+		})
+
+		Context("StresserManager previously tracked the same core", func() {
+			It("should return true for core already stressed", func() {
+				stresserManager.TrackCoreAlreadyStressed(0, 123)
+
+				Expect(stresserManager.IsCoreAlreadyStressed(0)).To(BeTrue())
+			})
+		})
+	})
+
+	When("TrackInjectorCores", func() {
+		var (
+			cgroup = cgroupManager()
+		)
+
+		Context("StresserManager is freshly initialized", func() {
+			It("should track injector cores and return new cores to apply stress", func() {
+				userRequestedCount := intstr.FromInt(2)
+				cores, err := stresserManager.TrackInjectorCores(cgroup, &userRequestedCount)
+
+				Expect(err).To(BeNil())
+				Expect(cores).To(Equal(cpuset.NewCPUSet(0, 1)))
+			})
+		})
+
+		Context("user request to target a specific number of cores", func() {
+			It("should discount core according to user request", func() {
+				userRequestedCount := intstr.FromInt(1)
+				cores, err := stresserManager.TrackInjectorCores(cgroup, &userRequestedCount)
+
+				Expect(err).To(BeNil())
+				Expect(cores).To(Equal(cpuset.NewCPUSet(0)))
+			})
+
+			It("should discount core, percentage round up, according to user request", func() {
+				userRequestedCount := intstr.FromString("30%")
+				cores, err := stresserManager.TrackInjectorCores(cgroup, &userRequestedCount)
+
+				Expect(err).To(BeNil())
+				Expect(cores).To(Equal(cpuset.NewCPUSet(0)))
+			})
+		})
+	})
+
+	When("calling TrackCoreAlreadyStressed", func() {
+		It("should record the stresser processID by coreID", func() {
+			stresserManager.TrackCoreAlreadyStressed(0, 123)
+
+			Expect(stresserManager.StresserPIDs()).To(HaveKeyWithValue(0, 123))
+		})
+	})
+})
+
+func cgroupManager() *ManagerMock {
+	cgroup := &ManagerMock{}
+	cgroup.On("Read", "cpuset", "cpuset.cpus").Return("0-1", nil)
+
+	return cgroup
+}

stress/stress_suite_test.go

@@ -0,0 +1,17 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2022 Datadog, Inc.
+
+package stress_test
+
+import (
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+	"testing"
+)
+
+func TestStress(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Stress Suite")
+}