kubelet/cm: code optimization for the static policy

Minor optimization in the code that attempts to assign whole
sockets/cores in case the number of CPUs requested is higher
than CPUs-per-socket/core: check if the number of requested
CPUs is higher than CPUs-per-socket/core before retrieving
and iterating the free sockets/cores, and break the loops
when that is no longer the case.

Signed-off-by: Arik Hadas <[email protected]>

Author: ahadas

pkg/kubelet/cm/cpumanager/cpu_assignment.go

@@ -158,25 +158,31 @@ func takeByTopology(topo *topology.CPUTopology, availableCPUs cpuset.CPUSet, num
 	// Algorithm: topology-aware best-fit
 	// 1. Acquire whole sockets, if available and the container requires at
 	//    least a socket's-worth of CPUs.
-	for _, s := range acc.freeSockets() {
-		if acc.needs(acc.topo.CPUsPerSocket()) {
+	if acc.needs(acc.topo.CPUsPerSocket()) {
+		for _, s := range acc.freeSockets() {
 			klog.V(4).Infof("[cpumanager] takeByTopology: claiming socket [%d]", s)
 			acc.take(acc.details.CPUsInSocket(s))
 			if acc.isSatisfied() {
 				return acc.result, nil
 			}
+			if !acc.needs(acc.topo.CPUsPerSocket()) {
+				break
+			}
 		}
 	}
 
 	// 2. Acquire whole cores, if available and the container requires at least
 	//    a core's-worth of CPUs.
-	for _, c := range acc.freeCores() {
-		if acc.needs(acc.topo.CPUsPerCore()) {
+	if acc.needs(acc.topo.CPUsPerCore()) {
+		for _, c := range acc.freeCores() {
 			klog.V(4).Infof("[cpumanager] takeByTopology: claiming core [%d]", c)
 			acc.take(acc.details.CPUsInCore(c))
 			if acc.isSatisfied() {
 				return acc.result, nil
 			}
+			if !acc.needs(acc.topo.CPUsPerCore()) {
+				break
+			}
 		}
 	}