Package: internal/runtime/cgroup

package cgroup Import Path internal/runtime/cgroup (on go.dev) Dependency Relation imports 4 packages, and imported by 2 packages

Involved Source Files cgroup.go cgroup_linux.go line_reader.go runtime.go

Package-Level Type Names (total 2)

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type CPU (struct) CPU owns the FDs required to read the CPU limit from a cgroup. Methods (only one) ( CPU) Close() As Outputs Of (at least one exported) func OpenCPU(scratch []byte) (CPU, error) As Inputs Of (at least one exported) func ReadCPULimit(c CPU) (float64, bool, error)

type Version int (basic type) Version indicates the cgroup version. As Outputs Of (at least 2) func FindCPU(out []byte, scratch []byte) (int, Version, error) func FindCPUCgroup(out []byte, scratch []byte) (int, Version, error) As Inputs Of (at least one exported) func FindCPUMountPoint(out, cgroup []byte, version Version, scratch []byte) (int, error) As Types Of (total 3) const V1 const V2 const VersionUnknown

Package-Level Functions (total 5)

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(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.

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 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 ReadCPULimit(c CPU) (float64, bool, error) Returns average CPU throughput limit from the cgroup, or ok false if there is no limit.

Package-Level Variables (only one)

var ErrNoCgroup error

Package-Level Constants (total 6)

const ParseSize = 65536 Required space to parse /proc/self/mountinfo and /proc/self/cgroup. See findCPUMount and findCPURelativePath.

const PathSize = 4096 Required space to store a path of the cgroup in the filesystem.

const ScratchSize = 69632 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.

const V1 Version = 1

const V2 Version = 2

const VersionUnknown Version = 0