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[release-v1.18] conformance tests, alternate formulate for cgroups cpu.weight #1597

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[release-v1.18] conformance tests, alternate formulate for cgroups cpu.weight #1597

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33 changes: 33 additions & 0 deletions test/conformance/runtime/cgroup_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@ package runtime
import (
"errors"
"fmt"
"math"
"strconv"
"strings"
"testing"
Expand Down Expand Up @@ -53,6 +54,25 @@ func isCgroupsV2(mounts []*types.Mount) (bool, error) {
return false, errors.New("Failed to find cgroup mount on /sys/fs/cgroup")
}

// from https://github.com/opencontainers/cgroups/pull/20/files
func convertCPUSharesToCgroupV2Value(cpuShares uint64) uint64 {
// The value of 0 means "unset".
if cpuShares == 0 {
return 0
}
if cpuShares <= 2 {
return 1
}
if cpuShares >= 262144 {
return 10000
}
l := math.Log2(float64(cpuShares))
// Quadratic function which fits min, max, and default.
exponent := (l*l+125*l)/612.0 - 7.0/34.0

return uint64(math.Ceil(math.Pow(10, exponent)))
}

// TestMustHaveCgroupConfigured verifies that the Linux cgroups are configured based on the specified
// resource limits and requests as delared by "MUST" in the runtime-contract.
func TestMustHaveCgroupConfigured(t *testing.T) {
Expand Down Expand Up @@ -84,6 +104,9 @@ func TestMustHaveCgroupConfigured(t *testing.T) {
"/sys/fs/cgroup/cpu.weight": strconv.FormatInt(((((resources.Requests.Cpu().MilliValue()*1024/1000)-2)*9999)/262142)+1, 10),
}

// cpu.weight conversion depends on runtime version, see https://github.com/kubernetes/kubernetes/issues/131216
expectedCgroupsV2CpuWeightAlternativeFormula := strconv.FormatUint(convertCPUSharesToCgroupV2Value(uint64(resources.Requests.Cpu().MilliValue()*1024/1000)), 10)

cgroups := ri.Host.Cgroups
cgroupV2, err := isCgroupsV2(ri.Host.Mounts)
if err != nil {
Expand Down Expand Up @@ -122,6 +145,16 @@ func TestMustHaveCgroupConfigured(t *testing.T) {
periodV2 = strings.Split(*cgroup.Value, " ")[1]
}

// cpu.weight conversion depends on runtime version, let's try the new formula first,
// if it fails, we fall back to the original formula we have in `expectedCgroups`
if cgroup.Name == "/sys/fs/cgroup/cpu.weight" {
if *cgroup.Value == expectedCgroupsV2CpuWeightAlternativeFormula {
continue
} else {
t.Logf("%s = %s, want: %s, falling back to the original cpu.weight formula", cgroup.Name, *cgroup.Value, expectedCgroupsV2CpuWeightAlternativeFormula)
}
}

if _, ok := expectedCgroups[cgroup.Name]; !ok {
// Service returned a value we don't test
t.Logf("%v cgroup returned, but not validated", cgroup.Name)
Expand Down
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