Module scheduler 

Work scheduler - priority-aware slot scanning for the persistent megakernel.

Extends the base slot-claim logic with priority partitioning: each priority level occupies a contiguous partition of the ring buffer. Workers scan from highest priority (0=CRITICAL) to lowest (4=IDLE), claiming the first PUBLISHED slot found. This ensures latency-sensitive work is processed before background tasks without true preemption.

Slot Layout Extension

The priority is encoded in ring_buffer[slot_base + PRIORITY_WORD]. The host sets this when publishing; the scheduler reads it to sort work into the right scan order.

Starvation Guard

After STARVATION_THRESHOLD consecutive high-priority claims, the scheduler forcibly scans lower-priority partitions for one iteration. This prevents priority inversion where a flood of CRITICAL slots starves NORMAL/“background” work indefinitely.

Modules

priority

Priority discriminants.

Constants

PRIORITY_LEVELS

Number of priority levels the scheduler supports.

PRIORITY_OFFSETS_BASE

Control word storing the priority partition offsets. control[PRIORITY_OFFSETS_BASE + pri] = first slot index for priority pri. control[PRIORITY_OFFSETS_BASE + PRIORITY_LEVELS] = total slot count (sentinel).

PRIORITY_STARVATION_COUNTER

Control word storing consecutive high-priority claims.

STARVATION_THRESHOLD

After this many consecutive claims at the same (or higher) priority, the scheduler forcibly scans lower-priority partitions for one iteration.

TENANT_FAIRNESS_THRESHOLD

After this many claims by a single tenant in a single worker’s “epoch”, the tenant is considered “greedy” and may be throttled.

Functions

check_priority_fairness

Policy helper: check if a priority level has exceeded its fairness quota.

check_tenant_fairness

Policy helper: check if a tenant has exceeded its fairness quota.

default_priority_offsets_array

Encode default priority partition offsets into a fixed array without allocation.

policy_offset_start

Policy helper: select the next slot to probe within a partition.

priority_partition_active_lane_count

Number of lanes that should actively probe one priority partition.

priority_partition_probe_budget

Upper bound on slot status probes for one priority partition.

priority_partition_probe_count

Number of strided probes each lane needs to cover a priority partition.

priority_scan_body

Build the priority-aware scan loop as Vec<Node> for composition.

priority_scan_body_with_stride

Build the priority-aware scan loop with an explicit global worker stride.

write_default_priority_offsets

Write default priority partition offsets into an encoded control buffer.