[release-1.16] Schduler: MAXFILLUP strategy will spread vreplicas acr…

…oss multiple pods (#8291)

* Schduler: MAXFILLUP strategy will spread vreplicas across multiple pods

the MAXFILLUP algorithm was using an affinity strategy, meaning that
it would prioritize adding new vreplicas to pods with the same resources.

However, the downside is that if one pod goes down or gets
re-scheduled the entire resource would be down and not produce
events. By spreading replicas across multiple real replicas we would
guarantee better availability.

Signed-off-by: Pierangelo Di Pilato <pierdipi@redhat.com>

* Remove configurable HA scheduler, fix reserved replicas logic

Signed-off-by: Pierangelo Di Pilato <pierdipi@redhat.com>

* Log reserved

Signed-off-by: Pierangelo Di Pilato <pierdipi@redhat.com>

* Handle unschedulables pods and always start from reserved no matter what is placements

Signed-off-by: Pierangelo Di Pilato <pierdipi@redhat.com>

* Add reserved + overcommit

Signed-off-by: Pierangelo Di Pilato <pierdipi@redhat.com>

* Add benchmark + reduce OrdinalFromPodName calls

Signed-off-by: Pierangelo Di Pilato <pierdipi@redhat.com>

* Handle unschedulable pods

Signed-off-by: Pierangelo Di Pilato <pierdipi@redhat.com>

---------

Signed-off-by: Pierangelo Di Pilato <pierdipi@redhat.com>
Co-authored-by: Pierangelo Di Pilato <pierdipi@redhat.com>

pkg/scheduler/doc.go

@@ -14,5 +14,5 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-// The scheduler is responsible for placing virtual pod (VPod) replicas within real pods.
+// Package scheduler is responsible for placing virtual pod (VPod) replicas within real pods.
 package scheduler

pkg/scheduler/placement.go

@@ -17,7 +17,6 @@ limitations under the License.
 package scheduler
 
 import (
-	"k8s.io/apimachinery/pkg/util/sets"
 	duckv1alpha1 "knative.dev/eventing/pkg/apis/duck/v1alpha1"
 )
 
@@ -29,24 +28,3 @@ func GetTotalVReplicas(placements []duckv1alpha1.Placement) int32 {
 	}
 	return r
 }
-
-// GetPlacementForPod returns the placement corresponding to podName
-func GetPlacementForPod(placements []duckv1alpha1.Placement, podName string) *duckv1alpha1.Placement {
-	for i := 0; i < len(placements); i++ {
-		if placements[i].PodName == podName {
-			return &placements[i]
-		}
-	}
-	return nil
-}
-
-// GetPodCount returns the number of pods with the given placements
-func GetPodCount(placements []duckv1alpha1.Placement) int {
-	set := sets.NewString()
-	for _, p := range placements {
-		if p.VReplicas > 0 {
-			set.Insert(p.PodName)
-		}
-	}
-	return set.Len()
-}

pkg/scheduler/placement_test.go

@@ -62,95 +62,3 @@ func TestGetTotalVReplicas(t *testing.T) {
 		})
 	}
 }
-
-func TestGetPlacementForPod(t *testing.T) {
-	ps1 := []duckv1alpha1.Placement{{PodName: "p", VReplicas: 2}}
-	ps2 := []duckv1alpha1.Placement{{PodName: "p", VReplicas: 2}, {PodName: "p2", VReplicas: 4}}
-	testCases := []struct {
-		name       string
-		podName    string
-		placements []duckv1alpha1.Placement
-		expected   *duckv1alpha1.Placement
-	}{
-		{
-			name:       "nil placements",
-			podName:    "p",
-			placements: nil,
-			expected:   nil,
-		},
-		{
-			name:       "empty placements",
-			podName:    "p",
-			placements: []duckv1alpha1.Placement{},
-			expected:   nil,
-		},
-		{
-			name:       "one placement",
-			placements: ps1,
-			podName:    "p",
-			expected:   &ps1[0],
-		}, {
-			name:       "mayne placements",
-			placements: ps2,
-			podName:    "p2",
-			expected:   &ps2[1],
-		},
-	}
-
-	for _, tc := range testCases {
-		t.Run(tc.name, func(t *testing.T) {
-			got := GetPlacementForPod(tc.placements, tc.podName)
-			if got != tc.expected {
-				t.Errorf("got %v, want %v", got, tc.expected)
-			}
-		})
-	}
-}
-func TestPodCount(t *testing.T) {
-	testCases := []struct {
-		name       string
-		placements []duckv1alpha1.Placement
-		expected   int
-	}{
-		{
-			name:       "nil placements",
-			placements: nil,
-			expected:   0,
-		},
-		{
-			name:       "empty placements",
-			placements: []duckv1alpha1.Placement{},
-			expected:   0,
-		},
-		{
-			name:       "one pod",
-			placements: []duckv1alpha1.Placement{{PodName: "d", VReplicas: 2}},
-			expected:   1,
-		},
-		{
-			name: "two pods",
-			placements: []duckv1alpha1.Placement{
-				{PodName: "p1", VReplicas: 2},
-				{PodName: "p2", VReplicas: 6},
-				{PodName: "p1", VReplicas: 6}},
-			expected: 2,
-		},
-		{
-			name: "three pods, one with no vreplicas",
-			placements: []duckv1alpha1.Placement{
-				{PodName: "p1", VReplicas: 2},
-				{PodName: "p2", VReplicas: 6},
-				{PodName: "p1", VReplicas: 0}},
-			expected: 2,
-		},
-	}
-
-	for _, tc := range testCases {
-		t.Run(tc.name, func(t *testing.T) {
-			got := GetPodCount(tc.placements)
-			if got != tc.expected {
-				t.Errorf("got %v, want %v", got, tc.expected)
-			}
-		})
-	}
-}