Scenarios
Scenarios define the scheduling conditions a test creates. Each scenario sets up cgroups, workers, and cpusets to produce a specific condition, then verifies the scheduler handles it correctly.
Canned scenarios (scenarios::*)
ktstr::scenario::scenarios provides curated scenario functions that
can be called directly from #[ktstr_test]:
use ktstr::prelude::*;
#[ktstr_test(llcs = 1, cores = 2, threads = 1)]
fn my_test(ctx: &Ctx) -> Result<AssertResult> {
scenarios::steady(ctx)
}| Function | Condition tested | Setup |
|---|---|---|
steady | Baseline fairness | 2 cgroups, no cpusets, equal CPU-spin load |
steady_llc | LLC-boundary scheduling | 2 cgroups with LLC-aligned cpusets |
oversubscribed | Dispatch under oversubscription | 2 cgroups, 32 mixed workers each |
cpuset_apply | Cpuset assignment on running tasks | Disjoint cpusets applied mid-run |
cpuset_clear | Cpuset removal on confined tasks | Cpusets cleared mid-run |
cpuset_resize | Cpuset resizing adaptation | Cpusets shrink then grow |
cgroup_add | New cgroup appearance | Cgroups added mid-run |
cgroup_remove | Cgroup removal while others run | Cgroups removed mid-run |
affinity_change | Affinity mask changes | Worker affinities randomized mid-run |
affinity_pinned | Narrow-affinity contention | Workers pinned to 2-CPU subset |
host_contention | Fairness between cgroup and host tasks | Host workers vs cgroup workers |
mixed_workloads | Mixed workload fairness | Heavy + bursty + IO cgroups |
nested_steady | Nested cgroup hierarchy | Workers in nested sub-cgroups |
nested_task_move | Cross-level task migration | Tasks moved between nested cgroups |
Additional custom_* functions are available in
ktstr::scenario::{affinity, basic, cpuset, dynamic, interaction, nested, performance, stress}. See the
API docs
for the full list.
Most tests use these canned functions or build custom scenarios with
CgroupDef and execute_defs / execute_steps (see
Ops and Steps). Custom scenarios receive a Ctx reference
and use the same building blocks; see
Custom Scenarios for the
Ctx struct and helper functions.