| name | rds-dv-randomization |
| description | Delay/traffic randomization in RDS-DV - the 19 named FlexConfigGen profiles, which layer to use, and the rule that randomized traffic does NOT prove fairness or arbitration correctness. Use when shaping stimulus timing, writing an arbiter/scheduler/picker test, or choosing a delay profile. |
rds-dv-randomization
READ FIRST: vault/handbook/INDEX.md (the handbook is the repo's memory; this skill is the
signpost). Canonical: vault/handbook/dv/randomization.md.
ONE OF THREE ORTHOGONAL AXES (see rds-dv-axes): BFM = who drives
(rds-dv-bfms); SEQUENCE = what traffic (rds-dv-axes); RANDOMIZATION = what
timing. Authoritative docs: /docs/components/shared/components_shared_flex_config_gen.md
and per-family components__randomization.md (axi4 has one).
Three layers, pick by what you configure: FlexConfigGen (named delay
profiles - start here), FlexRandomizer (the engine, for constraint shapes
no profile expresses), RandomizationConfig (per-field packet modes, not
delays).
List profiles instead of guessing:
from CocoTBFramework.components.shared.flex_config_gen import DEFAULT_PROFILES
19 exist. backtoback = zero delay = full saturation. Others worth knowing:
fast, constrained (general default), bursty, stress, slow,
heavy_pause, chaotic.
RANDOM TRAFFIC DOES NOT PROVE FAIRNESS. Random profiles leave gaps, so a
picker is never cornered and the request pattern decides who is served. A real
round-robin arbiter that starved 2 of 4 clients passed its randomized fairness
phase. For any arbiter/scheduler/picker: saturate deliberately, assert on
PER-CLIENT outcomes (a Jain index > 0.3 on 4 clients passes with two starved),
and mutation-check the assertion.
Two framework gaps recorded in the note: ArbiterMaster has its own private
profiles with no saturating option (use force_client_request), and
ArbiterCompliance.analyze_round_robin_compliance() is a stub returning
rr_efficiency: 1.0 unconditionally.
The handbook root is vault/handbook/INDEX.md - design/, dv/, fpga/, authoring/ areas,
atomic notes, wikilinked. When you learn a durable lesson in this domain,
ADD IT TO THE HANDBOOK NOTE, not to this skill.
