Module admission 

Admission by measured peaks: a job’s memory peak and average CPU predicted from the job history (Predictor), and the history replayed through admission by caps and by predictions, with or without a CPU budget (simulate), to show what each would have done with the same jobs; and what the host’s memory leaves runners (host). Pure: no I/O, no clock.

Modules

host

What the host’s memory leaves runners beside its other programs (ADR 0055): the slice’s runners may hold what they hold now without page cache plus the host’s MemAvailable, less a margin kept for the host’s page cache, so reclaim stays cheap; and nothing starts while the host, short of memory, stalls for it. Each bound has hysteresis, so a host at the edge does not start and hold runners by turns. Pure: the engine passes in the reading and what it remembers of the last plan.

Structs

CpuPrediction

The CPU a runner reserves for a job, in millicores, at most its profile’s cpus, and what it goes by.

Key

A job as admission tells jobs apart: its repository, workflow and name.

Prediction

The memory admission reserves for a job, at most its cap, and what it goes by.

Predictor

Predicts a job’s peak from the runs it learned.

Replay

What a replay did with the history’s jobs.

Enums

Copies

Whether other copies of a job may run beside the one predicted: queued with it, or running. A few light runs say little about a burst of copies, after a cache was invalidated, so only one copy at a time goes by them.

Policy

How a replay admits a queued job.

Constants

CPU_GRANULE

CPU predictions round up to this many millicores: a tenth of a CPU.

HIGH_WATER

While the slice uses this percent of its MemoryMax or more, measured admission starts nothing.

OWN_RUNS

From this many successful runs of its own, fewer than [sizing] min_jobs runs, a job reserves its own largest peak while no other copy of it is queued or running; otherwise the larger of that and its profile’s p95.

UNPREDICTABLE_FOR

For this long after a run at its cap or killed for memory, in milliseconds, its job is admitted at its cap: 7 days. After a run past what it reserved, its job reserves its largest peak for as long.

Functions

simulate

Replays jobs through policy: each arrives when it was queued and runs as long as it ran, in a profile with slots (by name; the config’s where absent) under the slice’s memory_max. Jobs start as soon as the policy admits them, oldest first, a job that does not fit letting a later one past, as scheduler::plan does. Measured admission predicts from the runs finished before it decides, as the daemon would, and holds each running job at its peak for its whole run, which the daemon does not see. A job with copies waiting or running beside it is predicted as one with Copies::Several. Each moment, the running jobs are predicted again, the first running copy of a job going by its own runs, as the daemon does each tick. Unlike the daemon, the replay knows a job from its start: it never sees a runner whose job is not known yet, and the order jobs started stands for the daemon’s slot order.