DRA scheduler: also pre-compute the unique ResourceSlice.NodeName

Converting a node's name once to a unique string and then converting to many
unique names is faster than memory comparisons.

    goos: linux
    goarch: amd64
    pkg: k8s.io/kubernetes/test/integration/scheduler_perf
    cpu: Intel(R) Core(TM) i9-7980XE CPU @ 2.60GHz
                                                                                       │            before            │                       after                        │
                                                                                       │ SchedulingThroughput/Average │ SchedulingThroughput/Average  vs base              │
    PerfScheduling/SchedulingWithResourceClaimTemplateStructured/5000pods_500nodes-36                      36.65 ± 2%                     36.89 ± 2%       ~ (p=0.452 n=6)
    PerfScheduling/SteadyStateClusterResourceClaimTemplateStructured/empty_100nodes-36                     106.7 ± 3%                     105.7 ± 5%       ~ (p=0.701 n=6)
    PerfScheduling/SteadyStateClusterResourceClaimTemplateStructured/empty_500nodes-36                     119.7 ± 3%                     117.8 ± 3%       ~ (p=0.084 n=6)
    PerfScheduling/SteadyStateClusterResourceClaimTemplateStructured/half_100nodes-36                      121.1 ± 4%                     119.5 ± 4%       ~ (p=0.297 n=6)
    PerfScheduling/SteadyStateClusterResourceClaimTemplateStructured/half_500nodes-36                      63.72 ± 3%                     63.22 ± 2%       ~ (p=0.485 n=6)
    PerfScheduling/SteadyStateClusterResourceClaimTemplateStructured/full_100nodes-36                      110.2 ± 2%                     109.5 ± 2%       ~ (p=0.258 n=6)
    PerfScheduling/SteadyStateClusterResourceClaimTemplateStructured/full_500nodes-36                      28.16 ± 5%                     27.56 ± 5%       ~ (p=0.513 n=6)
    geomean                                                                                                73.15                          72.44       -0.98%

staging/src/k8s.io/dynamic-resource-allocation/api/conversion.go

@@ -29,11 +29,19 @@ var (
 )
 
 func Convert_api_UniqueString_To_string(in *UniqueString, out *string, s conversion.Scope) error {
+	if *in == NullUniqueString {
+		*out = ""
+		return nil
+	}
 	*out = in.String()
 	return nil
 }
 
 func Convert_string_To_api_UniqueString(in *string, out *UniqueString, s conversion.Scope) error {
+	if *in == "" {
+		*out = NullUniqueString
+		return nil
+	}
 	*out = UniqueString(unique.Make(*in))
 	return nil
 }

staging/src/k8s.io/dynamic-resource-allocation/api/types.go

@@ -31,7 +31,7 @@ type ResourceSlice struct {
 type ResourceSliceSpec struct {
 	Driver       UniqueString
 	Pool         ResourcePool
-	NodeName     string
+	NodeName     UniqueString
 	NodeSelector *v1.NodeSelector
 	AllNodes     bool
 	Devices      []Device

staging/src/k8s.io/dynamic-resource-allocation/api/zz_generated.conversion.go

@@ -246,7 +246,9 @@ func autoConvert_api_ResourceSliceSpec_To_v1alpha3_ResourceSliceSpec(in *Resourc
 	if err := Convert_api_ResourcePool_To_v1alpha3_ResourcePool(&in.Pool, &out.Pool, s); err != nil {
 		return err
 	}
-	out.NodeName = in.NodeName
+	if err := Convert_api_UniqueString_To_string(&in.NodeName, &out.NodeName, s); err != nil {
+		return err
+	}
 	out.NodeSelector = (*v1.NodeSelector)(unsafe.Pointer(in.NodeSelector))
 	out.AllNodes = in.AllNodes
 	if in.Devices != nil {
@@ -275,7 +277,9 @@ func autoConvert_v1alpha3_ResourceSliceSpec_To_api_ResourceSliceSpec(in *v1alpha
 	if err := Convert_v1alpha3_ResourcePool_To_api_ResourcePool(&in.Pool, &out.Pool, s); err != nil {
 		return err
 	}
-	out.NodeName = in.NodeName
+	if err := Convert_string_To_api_UniqueString(&in.NodeName, &out.NodeName, s); err != nil {
+		return err
+	}
 	out.NodeSelector = (*v1.NodeSelector)(unsafe.Pointer(in.NodeSelector))
 	out.AllNodes = in.AllNodes
 	if in.Devices != nil {

staging/src/k8s.io/dynamic-resource-allocation/structured/allocator.go

@@ -839,7 +839,7 @@ func (alloc *allocator) createNodeSelector(result []internalDeviceResult) (*v1.N
 
 	for i := range result {
 		slice := result[i].slice
-		if slice.Spec.NodeName != "" {
+		if slice.Spec.NodeName != draapi.NullUniqueString {
 			// At least one device is local to one node. This
 			// restricts the allocation to that node.
 			return &v1.NodeSelector{
@@ -847,7 +847,7 @@ func (alloc *allocator) createNodeSelector(result []internalDeviceResult) (*v1.N
 					MatchFields: []v1.NodeSelectorRequirement{{
 						Key:      "metadata.name",
 						Operator: v1.NodeSelectorOpIn,
-						Values:   []string{slice.Spec.NodeName},
+						Values:   []string{slice.Spec.NodeName.String()},
 					}},
 				}},
 			}, nil

staging/src/k8s.io/dynamic-resource-allocation/structured/pools.go

@@ -35,11 +35,15 @@ import (
 // Both is recorded in the result.
 func GatherPools(ctx context.Context, slices []*resourceapi.ResourceSlice, node *v1.Node) ([]*Pool, error) {
 	pools := make(map[PoolID]*Pool)
+	nodeName := ""
+	if node != nil {
+		nodeName = node.Name
+	}
 
 	for _, slice := range slices {
 		switch {
 		case slice.Spec.NodeName != "":
-			if slice.Spec.NodeName == node.Name {
+			if slice.Spec.NodeName == nodeName {
 				if err := addSlice(pools, slice); err != nil {
 					return nil, fmt.Errorf("add node slice %s: %w", slice.Name, err)
 				}
@@ -49,6 +53,7 @@ func GatherPools(ctx context.Context, slices []*resourceapi.ResourceSlice, node
 				return nil, fmt.Errorf("add cluster slice %s: %w", slice.Name, err)
 			}
 		case slice.Spec.NodeSelector != nil:
+			// TODO: move conversion into api.
 			selector, err := nodeaffinity.NewNodeSelector(slice.Spec.NodeSelector)
 			if err != nil {
 				return nil, fmt.Errorf("node selector in resource slice %s: %w", slice.Name, err)