RISC-V Design · All levels

Hazard Detection Basics in Decode: Reports and Metrics

Reports and Metrics for Hazard Detection Basics in Decode.

Reports and metrics

Reports and Metrics for Hazard Detection Basics in Decode is anchored on RAW stall cycles per kilo-instruction and percentage of avoidable stalls removed by forwarding.. Convert observations into mechanism-backed decisions with explicit ownership.

Before/after trend

diagram

BEFORE / AFTER TREND - Hazard Detection Basics in Decode

RAW stall cycles per kilo-instruction and percentage of avoidable stalls removed by forwarding.
  ^
  |                           o target band
  |                    o after fix + reruns
  |             o
  |      o baseline (failing)
  +--------------------------------------------------> iteration
       capture issue      isolate mechanism      close + monitor

Use this view to confirm the gain is causal and stable across seeds.

Root-cause tree

diagram

ROOT CAUSE TREE - Hazard Detection Basics in Decode

RAW stall cycles per kilo-instruction and percentage of avoidable stalls removed by forwarding. regressed
          |
   reproducible on fixed seed?
      /                 \
    no                   yes
    |                     |
env/tool drift       first failing domain?
                     /        |         \
                  decode    execute    memory/MMU
                    |         |            |
               control map  bypass/FU   TLB/walk/perm
                    |
         privilege/CSR side effects checked?

Stop at first confirmed mechanism, then assign explicit owner + fix proof.

Track RAW stall cycles per kilo-instruction and percentage of avoidable stalls removed by forwarding. on representative workloads, not just microbenchmarks.
Include build/runtime/privilege metadata in report headers.
Pair performance movement with correctness and reliability checks.
Report tail stability, not only mean uplift.

Practice this lesson