package cgroup

import "internal/runtime/cgroup"

Index

• Constants
• Variables
• func FindCPUMountPoint(out, cgroup []byte, version Version, scratch []byte) (int, error)
• func ReadCPULimit(c CPU) (float64, bool, error)
• type CPU
  • func OpenCPU(scratch []byte) (CPU, error)
  • func (c CPU) Close()
• type Version
  • func FindCPU(out []byte, scratch []byte) (int, Version, error)
  • func FindCPUCgroup(out []byte, scratch []byte) (int, Version, error)

Constants

const (
	// Required amount of scratch space for CPULimit.
	//
	// TODO(prattmic): This is shockingly large (~70KiB) due to the (very
	// unlikely) combination of extremely long paths consisting mostly
	// escaped characters. The scratch buffer ends up in .bss in package
	// runtime, so it doesn't contribute to binary size and generally won't
	// be faulted in, but it would still be nice to shrink this. A more
	// complex parser that did not need to keep entire lines in memory
	// could get away with much less. Alternatively, we could do a one-off
	// mmap allocation for this buffer, which is only mapped larger if we
	// actually need the extra space.
	ScratchSize = PathSize + ParseSize

	// Required space to store a path of the cgroup in the filesystem.
	PathSize = _PATH_MAX

	// Required space to parse /proc/self/mountinfo and /proc/self/cgroup.
	// See findCPUMount and findCPURelativePath.
	ParseSize = 4 * escapedPathMax
)

Variables

var (
	ErrNoCgroup error = stringError("not in a cgroup")
)

Functions

func FindCPUMountPoint

func FindCPUMountPoint(out, cgroup []byte, version Version, scratch []byte) (int, error)

FindCPUMountPoint finds the mount point containing the specified cgroup and version with cpu controller, and compose the full path to the cgroup in out. scratch is a scratch buffer for internal use.

out must have length PathSize, may overlap with cgroup. scratch must have length ParseSize.

Returns the number of bytes written to out.

Returns ErrNoCgroup if no matching mount point is found.

func ReadCPULimit

func ReadCPULimit(c CPU) (float64, bool, error)

Returns average CPU throughput limit from the cgroup, or ok false if there is no limit.

Types

type CPU

type CPU struct {
	// contains filtered or unexported fields
}

CPU owns the FDs required to read the CPU limit from a cgroup.

func OpenCPU

func OpenCPU(scratch []byte) (CPU, error)

OpenCPU returns a CPU for the CPU cgroup containing the current process, or ErrNoCgroup if the process is not in a CPU cgroup.

scratch must have length ScratchSize.

func (CPU) Close

func (c CPU) Close()

type Version

type Version int

Version indicates the cgroup version.

const (
	VersionUnknown Version = iota
	V1
	V2
)

func FindCPU

func FindCPU(out []byte, scratch []byte) (int, Version, error)

FindCPU finds the path to the CPU cgroup that this process is a member of and places it in out. scratch is a scratch buffer for internal use.

out must have length PathSize. scratch must have length ParseSize.

Returns the number of bytes written to out and the cgroup version (1 or 2).

Returns ErrNoCgroup if the process is not in a CPU cgroup.

func FindCPUCgroup

func FindCPUCgroup(out []byte, scratch []byte) (int, Version, error)

FindCPUCgroup finds the path to the CPU cgroup that this process is a member of and places it in out. scratch is a scratch buffer for internal use.

out must have length PathSize. scratch must have length ParseSize.

Returns the number of bytes written to out and the cgroup version (1 or 2).

Returns ErrNoCgroup if the process is not in a CPU cgroup.