Documentation
¶
Overview ¶
Package cgroup is a thin view of a delegated cgroup v2 subtree: create leaves with a memory ceiling and group OOM, open them for clone3, read what they charge, and kill them. Plain file operations; nothing here is clever, which is the point.
Index ¶
- func NVIDIAPresent() bool
- func ScopeOf(procCgroup string) string
- type Dir
- func (d Dir) Ceiling(name string) uint64
- func (d Dir) Child(name string) Dir
- func (d Dir) Children(prefix string) ([]Dir, error)
- func (d Dir) Create(memMax uint64, oomGroup bool) error
- func (d Dir) Ensure(controllers ...string) error
- func (d Dir) Exists() bool
- func (d Dir) Kill() error
- func (d Dir) MemoryCurrent() (uint64, error)
- func (d Dir) Name() string
- func (d Dir) OOMKills() (uint64, error)
- func (d Dir) Open() (*os.File, error)
- func (d Dir) PSI() (PSI, error)
- func (d Dir) PidsMaxHits() (uint64, error)
- func (d Dir) Procs() ([]int, error)
- func (d Dir) Remove() error
- func (d Dir) SetCeiling(high, max uint64) error
- func (d Dir) SetMemoryMin(b uint64) error
- func (d Dir) SetPidsMax(n uint64) error
- func (d Dir) Stat(key string) (uint64, error)
- type GPUGuard
- type PSI
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
Types ¶
type Dir ¶
type Dir struct{ Path string }
Dir is one cgroup directory.
func Delegate ¶
Delegate prepares root, the cgroup fiberd was started in, for the runtime to carve grants under. It needs controllers in cgroup.subtree_control, and a cgroup with processes may not enable any (the no-internal-process rule), so every process there first moves into a `fiberd` leaf. The memory limit whatever started fiberd put on root (a kubelet, Slurm's task/cgroup) stays the ceiling on everything below. Returns the `grants` subtree the runtime owns. Idempotent: an already delegated root is left alone. Controllers the root cannot offer (a Slurm step gets cpuset, cpu and memory, no pids) are skipped; memory is required. The root is live, so a process can enter it after the move and the kernel then refuses the controller. Delegate moves the newcomers and tries again a few times before it gives up.
func Own ¶
Own is the cgroup this process runs in, under mount (normally /sys/fs/cgroup). In a private cgroup namespace that is the mount's root; in the host's (what a privileged Pod gets under containerd, or a Slurm job step under proctrack/cgroup) it is the path /proc/self/cgroup names. Returns the mount root when the named path does not exist under it.
func (Dir) Ceiling ¶
Ceiling is the nearest limit above d: the smallest numeric value of the control file name (memory.max, pids.max) on d's ancestors, read upward until a directory without the file, which is the end of the delegated tree or the mount itself. A private cgroup namespace shows the container's own limit on the mount's root. 0 when every ancestor says max, as a bare host's root does.
func (Dir) Create ¶
Create makes a leaf with a memory ceiling (0 = none) and, when oomGroup is set, makes the kernel kill the whole leaf at once when it is hit.
func (Dir) Ensure ¶
Ensure creates the directory (if needed) and enables controllers for its children, so leaves under it get memory.max and friends.
func (Dir) MemoryCurrent ¶
MemoryCurrent is what the leaf charges now: for a forked fiber, the pages it has made private since the fork, which is W.
func (Dir) PidsMaxHits ¶
PidsMaxHits counts forks refused because this group was at pids.max (pids.events max). It is 0 without a pids controller.
func (Dir) SetCeiling ¶
SetCeiling sets memory.high (throttle: the kernel reclaims and stalls the group, which PSI reports) and memory.max (the hard stop). max of 0 leaves the hard limit unset. Swap is closed for the group: the ceiling is resident memory, and a home that lets jobs swap (Slurm without ConstrainSwapSpace) would otherwise let the zygote's pages slip out under the ceiling instead of stalling, and the ladder would never see the pressure it acts on.
func (Dir) SetMemoryMin ¶
SetMemoryMin protects b bytes of the group from reclaim. The kernel caps it at the parent's effective memory.min, so a protection only holds when every ancestor up to the delegation root carries one too.
func (Dir) SetPidsMax ¶
SetPidsMax caps the tasks in the group and its descendants. 0 leaves it unlimited. A group whose parent offers no pids controller (a Slurm step) has no pids.max and is left alone.
Source Files