Centralize cores and period/quota conversion code

Signed-off-by: Jordan Christiansen <xordspar0@gmail.com>

pkg/util/utils.go

@@ -653,3 +653,26 @@ func CreateCidFile(cidfile string, id string) error {
 	cidFile.Close()
 	return nil
 }
+
+// DefaultCPUPeriod is the default CPU period is 100us, which is the same default
+// as Kubernetes.
+const DefaultCPUPeriod uint64 = 100000
+
+// CoresToPeriodAndQuota converts a fraction of cores to the equivalent
+// Completely Fair Scheduler (CFS) parameters period and quota.
+//
+// Cores is a fraction of the CFS period that a container may use. Period and
+// Quota are in microseconds.
+func CoresToPeriodAndQuota(cores float64) (uint64, int64) {
+	return DefaultCPUPeriod, int64(cores * float64(DefaultCPUPeriod))
+}
+
+// PeriodAndQuotaToCores takes the CFS parameters period and quota and returns
+// a fraction that represents the limit to the number of cores that can be
+// utilized over the scheduling period.
+//
+// Cores is a fraction of the CFS period that a container may use. Period and
+// Quota are in microseconds.
+func PeriodAndQuotaToCores(period uint64, quota int64) float64 {
+	return float64(quota) / float64(period)
+}