When runc updates the values ​​of cpu-rt-period and cpu-rt-runtime synchronously, an error occurs.

[zhongTao99]

Description

For example:

1. When the updated cpu-rt-runtime value becomes smaller and the cpu-rt-period value also becomes smaller, the update is unsuccessful.
   （1）when creating a container, set the parameters to: --cpu-rt-runtime 950000 --cpu-rt-period 1000000.
   （2）If the update parameters are --cpu-rt-runtime 5000 --cpu-rt-period 960000, runc cannot successfully updated。It will report an error: Invalid parameter

The reason is that in the SetRtSched function of runc, the cpu-rt-period value is written first and then the cpu-rt-runtime value. If the cpu-rt-period value is written without complying with the cgroup rules, an error will be reported and returned directly.

func (s *CpuGroup) SetRtSched(path string, r *configs.Resources) error {
	if r.CpuRtPeriod != 0 {
		if err := cgroups.WriteFile(path, "cpu.rt_period_us", strconv.FormatUint(r.CpuRtPeriod, 10)); err != nil {
			return err
		}
	}
	if r.CpuRtRuntime != 0 {
		if err := cgroups.WriteFile(path, "cpu.rt_runtime_us", strconv.FormatInt(r.CpuRtRuntime, 10)); err != nil {
			return err
		}
	}
	return nil
}

Describe the results you received and expected

runc successfully updated

What version of runc are you using?

runc version 1.1.3
commit: v1.1.3-0-g6724737f-dirty
spec: 1.0.2-dev
go: go1.20.8
libseccomp: 2.5.1