topology-aware: add prefer-shared-partial-llc-group annotation.

Add an annotation to indicate a CPU allocation preference with
the last/partial LLC group shared instead of using an idle one.

The full annotation syntax is
  metadata:
    annotations:
      prefer-shared-partial-llc-group.resource-policy.nri.io: "true"

Signed-off-by: Krisztian Litkey <[email protected]>

cmd/plugins/topology-aware/policy/pod-preferences.go

@@ -47,6 +47,8 @@ const (
 	keyCpuPriorityPreference = "prefer-cpu-priority"
 	// annotation key for hiding hyperthreads from allocated CPU sets
 	keyHideHyperthreads = "hide-hyperthreads"
+	// annotation to prefer shared LLC groups for the last (but not first) partial one
+	keyPreferSharedPartialLLCGroup = "prefer-shared-parital-llc-group"
 
 	// effective annotation key for isolated CPU preference
 	preferIsolatedCPUsKey = keyIsolationPreference + "." + kubernetes.ResmgrKeyNamespace
@@ -62,6 +64,8 @@ const (
 	preferCpuPriorityKey = keyCpuPriorityPreference + "." + kubernetes.ResmgrKeyNamespace
 	// effective annotation key for hiding hyperthreads
 	hideHyperthreadsKey = keyHideHyperthreads + "." + kubernetes.ResmgrKeyNamespace
+	// effective annotation key for shared partial LLC groups preference
+	preferSharedPartialLLCGroupKey = keyPreferSharedPartialLLCGroup + "." + kubernetes.ResmgrKeyNamespace
 )
 
 // cpuClass is a type of CPU to allocate
@@ -198,6 +202,19 @@ func hideHyperthreadsPreference(pod cache.Pod, container cache.Container) bool {
 	return hide
 }
 
+// sharedPartialLLCGroupPreference returns whether a container prefers shared partial LLC groups.
+func sharedPartialLLCGroupPreference(container cache.Container) bool {
+	value, ok := container.GetEffectiveAnnotation(preferSharedPartialLLCGroupKey)
+	if !ok {
+		return false
+	}
+	shared, err := strconv.ParseBool(value)
+	if err != nil {
+		return false
+	}
+	return shared
+}
+
 // memoryTypePreference returns what type of memory should be allocated for the container.
 //
 // If the effective annotations are not found, this function falls back to

cmd/plugins/topology-aware/policy/resources.go

@@ -403,17 +403,23 @@ func (cs *supply) AllocateCPU(r Request) (Grant, error) {
 	}
 
 	// allocate isolated exclusive CPUs or slice them off the sharable set
+	allocFlags := cpuallocator.AllocDefault
+	if sharedPartialLLCGroupPreference(cr.GetContainer()) {
+		log.Info("using shared LLC group preference for %s", cr.GetContainer().PrettyName())
+		allocFlags |= cpuallocator.PreferPartialSharedGroups
+	}
+
 	switch {
 	case full > 0 && cs.isolated.Size() >= full && cr.isolate:
-		exclusive, err = cs.takeCPUs(&cs.isolated, nil, full, cr.CPUPrio())
+		exclusive, err = cs.takeCPUs(&cs.isolated, nil, full, cr.CPUPrio().Option(), cpuallocator.WithAllocFlags(allocFlags))
 		if err != nil {
 			return nil, policyError("internal error: "+
 				"%s: can't take %d exclusive isolated CPUs from %s: %v",
 				cs.node.Name(), full, cs.isolated, err)
 		}
 
 	case full > 0 && cs.AllocatableSharedCPU() > 1000*full:
-		exclusive, err = cs.takeCPUs(&cs.sharable, nil, full, cr.CPUPrio())
+		exclusive, err = cs.takeCPUs(&cs.sharable, nil, full, cr.CPUPrio().Option(), cpuallocator.WithAllocFlags(allocFlags))
 		if err != nil {
 			return nil, policyError("internal error: "+
 				"%s: can't take %d exclusive CPUs from %s: %v",
@@ -509,8 +515,8 @@ func (cs *supply) Reserve(g Grant, o *libmem.Offer) (map[string]libmem.NodeMask,
 }
 
 // takeCPUs takes up to cnt CPUs from a given CPU set to another.
-func (cs *supply) takeCPUs(from, to *cpuset.CPUSet, cnt int, prio cpuPrio) (cpuset.CPUSet, error) {
-	cset, err := cs.node.Policy().cpuAllocator.AllocateCpus(from, cnt, prio.Option())
+func (cs *supply) takeCPUs(from, to *cpuset.CPUSet, cnt int, options ...cpuallocator.Option) (cpuset.CPUSet, error) {
+	cset, err := cs.node.Policy().cpuAllocator.AllocateCpus(from, cnt, options...)
 	if err != nil {
 		return cset, err
 	}