runtimehandler: mixedcpus: fix quota calculation

turns out the `podManager.GetCgroups()` doesn\'t return
any information with regards to its existing resources.

We should put some extra effort in order to find and calculate
the actual pod quota.
We need to sum the quota value from each container + the shared cpus
and that should be our new pod quota.

Signed-off-by: Talor Itzhak <[email protected]>

internal/runtimehandlerhooks/high_performance_hooks_linux.go

@@ -51,6 +51,8 @@ const (
 
 const (
 	cgroupSubTreeControl = "cgroup.subtree_control"
+	cgroupV1QuotaFile    = "cpu.cfs_quota_us"
+	cgroupV2QuotaFile    = "cpu.max"
 	cpusetCpus           = "cpuset.cpus"
 	cpusetCpusExclusive  = "cpuset.cpus.exclusive"
 	IsolatedCPUsEnvVar   = "OPENSHIFT_ISOLATED_CPUS"
@@ -1077,25 +1079,21 @@ func injectQuotaGivenSharedCPUs(c *oci.Container, podManager cgroups.Manager, co
 	}
 
 	// pod level operations
-	podCgroup, err := podManager.GetCgroups()
-	if err != nil {
-		return err
-	}
-	newPodQuota, err := calculatePodQuota(&sharedCPUSet, podCgroup.Resources.CpuQuota, podCgroup.Resources.CpuPeriod)
+	newPodQuota, err := calculatePodQuota(&sharedCPUSet, podManager, *cpuSpec.Period)
 	if err != nil {
 		return fmt.Errorf("failed to calculate pod quota: %w", err)
 	}
+	// the Set function knows to handle -1 value for both v1 and v2
 	err = podManager.Set(&configs.Resources{
 		SkipDevices: true,
 		CpuQuota:    newPodQuota,
 	})
 	if err != nil {
 		return err
 	}
-
 	// container level operations
 	ctrCPUSet := isolatedCPUSet.Union(sharedCPUSet)
-	ctrQuota, err := calculateMaximalQuota(&ctrCPUSet, *(cpuSpec.Period))
+	ctrQuota, err := calculateMaximalQuota(&ctrCPUSet, *cpuSpec.Period)
 	if err != nil {
 		return fmt.Errorf("failed to calculate container %s quota: %w", c.ID(), err)
 	}
@@ -1119,12 +1117,53 @@ func calculateMaximalQuota(cpus *cpuset.CPUSet, period uint64) (quota int64, err
 	return
 }
 
-func calculatePodQuota(sharedCpus *cpuset.CPUSet, existingQuota int64, period uint64) (int64, error) {
+func calculatePodQuota(sharedCpus *cpuset.CPUSet, podManager cgroups.Manager, period uint64) (int64, error) {
+	var quotaGetFunc func(cgroups.Manager) (string, error)
+	if node.CgroupIsV2() {
+		quotaGetFunc = getPodQuotaV2
+	} else {
+		quotaGetFunc = getPodQuotaV1
+	}
+	existingQuota, err := quotaGetFunc(podManager)
+	if err != nil {
+		return 0, err
+	}
+	// the pod is already at its maximal quota
+	// we return -1 for both cgroup v1 and v2
+	if existingQuota == "-1" || existingQuota == "max" {
+		return -1, nil
+	}
 	additionalQuota, err := calculateMaximalQuota(sharedCpus, period)
 	if err != nil {
 		return 0, err
 	}
-	return existingQuota + additionalQuota, err
+	q, err := strconv.ParseInt(existingQuota, 10, 0)
+	if err != nil {
+		return 0, err
+	}
+	return q + additionalQuota, err
+}
+
+func getPodQuotaV1(mng cgroups.Manager) (string, error) {
+	controllerPath := mng.Path("cpu")
+	q, err := cgroups.ReadFile(controllerPath, cgroupV1QuotaFile)
+	if err != nil {
+		return "", err
+	}
+	cpuQuota := strings.TrimSuffix(q, "\n")
+	return cpuQuota, nil
+}
+
+func getPodQuotaV2(mng cgroups.Manager) (string, error) {
+	controllerPath := mng.Path("")
+	cpuQuotaAndPeriod, err := cgroups.ReadFile(controllerPath, cgroupV2QuotaFile)
+	if err != nil {
+		return "", err
+	}
+	// in v2, the quota file contains both quota and period
+	// example: max 100000
+	cpuQuota := strings.Split(strings.TrimSuffix(cpuQuotaAndPeriod, "\n"), " ")[0]
+	return cpuQuota, nil
 }
 
 func injectCpusetEnv(c *oci.Container, isolated, shared *cpuset.CPUSet) {