Files
LithosAnanake/include/starkernel/vm
Robert Allan JamesandClaude Sonnet 5 89d8c08582 stadium: wire STADIUM_CAPACITY_TICK in as a flat threshold, not a scheduler
Closes FABRIC-2.md's last open §12 Q5 question. fleet_heartbeat_tick_count
is fed by every live VM's own vm_tick(), not one VM's, so it was reaching
HEARTBEAT_INFERENCE_FREQUENCY (shared/borrowed from the per-VM inference
gate) several times faster than intended with more than one VM live -
backwards from FABRIC.md §22.4's required ~1000:1 separation.

What's actually gated turned out to be low-stakes: vm_physics_tick()
(capsule_vm_physics.c:397) is a passive statistics refit - re-sorts a
window of past heat-transfer samples and recomputes a median rate
estimate. It doesn't move heat or arbitrate capacity. Firing too often
just meant a noisier statistic recomputed more frequently than planned,
not incorrect behavior.

Considered and explicitly rejected: scaling the threshold by live VM
count at the check site. That's the first brick of a scheduler - reading
fleet state to adjust a rate dynamically - which this project has
deliberately avoided building. Implemented instead: STADIUM_CAPACITY_TICK
(existing Kconfig symbol, defined but never read by any code path) now
gates vm_physics_heartbeat_tick()'s call directly, replacing the borrowed
HEARTBEAT_INFERENCE_FREQUENCY. Default bumped 1000 -> 4000, a flat
constant picked once for Tripod's known 4-VM topology, same kind of
placeholder as every other frequency knob in Kconfig.kernel - not
computed from anything at runtime. Renamed fleet_last_inference_tick ->
fleet_last_capacity_tick to match. Still one clock, one counter
(fleet_heartbeat_tick_count) - just a bigger flat divisor on it.

Three-arch QEMU acceptance: all clean to ok>, identical Stadium
conservation invariant on all three (resident_sum=43691 reservoir=21845
sum=65536). logs/20260815-093425/amd64, logs/20260815-093521/aarch64,
logs/20260815-093641/riscv64.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
2026-08-15 09:37:58 -04:00
..
2026-08-01 07:49:56 -04:00

include/starkernel/vm/

Headers for the kernel-side VM subsystem (src/starkernel/vm/).

  • arena.h — the capsule arena allocator: fixed-region allocation for capsule payload data, separate from kmalloc's general kernel heap.
  • parity.h — the birth/execution parity-record logger: declares the logging interface used to record VM ID, capsule content hash, and dictionary hash on every capsule birth, enabling offline determinism verification across independent kernel runs.

See include/starkernel/vm/bootstrap/README.md for the VM bootstrap subsystem.