mirror of
https://github.com/aljazceru/kata-containers.git
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bcf181b7ee
As github.com/containerd/cgroups doesn't support scope units which are essential in some cases lets create the cgroups manually and load it trough the cgroups api This is currently done only when there's single sandbox cgroup (sandbox_cgroup_only=true), otherwise we set it as static cgroup path as it used to be (until a proper soultion for overhead cgroup under systemd will be suggested) Fixes: #2868 Signed-off-by: Snir Sheriber <ssheribe@redhat.com>
63 lines
1.4 KiB
Go
63 lines
1.4 KiB
Go
package internal
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import (
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"fmt"
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"io/ioutil"
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"strings"
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"sync"
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)
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var sysCPU struct {
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once sync.Once
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err error
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num int
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}
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// PossibleCPUs returns the max number of CPUs a system may possibly have
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// Logical CPU numbers must be of the form 0-n
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func PossibleCPUs() (int, error) {
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sysCPU.once.Do(func() {
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sysCPU.num, sysCPU.err = parseCPUsFromFile("/sys/devices/system/cpu/possible")
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})
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return sysCPU.num, sysCPU.err
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}
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func parseCPUsFromFile(path string) (int, error) {
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spec, err := ioutil.ReadFile(path)
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if err != nil {
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return 0, err
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}
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n, err := parseCPUs(string(spec))
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if err != nil {
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return 0, fmt.Errorf("can't parse %s: %v", path, err)
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}
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return n, nil
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}
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// parseCPUs parses the number of cpus from a string produced
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// by bitmap_list_string() in the Linux kernel.
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// Multiple ranges are rejected, since they can't be unified
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// into a single number.
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// This is the format of /sys/devices/system/cpu/possible, it
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// is not suitable for /sys/devices/system/cpu/online, etc.
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func parseCPUs(spec string) (int, error) {
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if strings.Trim(spec, "\n") == "0" {
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return 1, nil
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}
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var low, high int
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n, err := fmt.Sscanf(spec, "%d-%d\n", &low, &high)
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if n != 2 || err != nil {
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return 0, fmt.Errorf("invalid format: %s", spec)
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}
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if low != 0 {
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return 0, fmt.Errorf("CPU spec doesn't start at zero: %s", spec)
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}
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// cpus is 0 indexed
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return high + 1, nil
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}
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