RISC-V Design ยท All levels
Five-Stage Pipeline Partitioning and Timing Contracts: Worked Example
Worked Example for Five-Stage Pipeline Partitioning and Timing Contracts.
Worked example
Worked Example for Five-Stage Pipeline Partitioning and Timing Contracts is anchored on Post-layout Fmax versus stage slack spread, plus bubble rate introduced by stage-boundary timing fixes.. Convert observations into mechanism-backed decisions with explicit ownership.
A regression flags Post-layout Fmax versus stage slack spread, plus bubble rate introduced by stage-boundary timing fixes.. Strong closure isolates first failing mechanism, proves causality, applies one bounded change, and validates blast radius.
System view
RISC-V PIPELINE DIAGRAM - Five-Stage Pipeline Partitioning and Timing Contracts
PC -> IF -> ID -> EX -> MEM -> WB
| | | | |
i-cache decode ALU/BR LSU regfile write
\ |
+-> branch resolve + redirect
Hot paths:
- branch + load-use dependencies in ID/EX
- memory latency stretching MEM stage
- writeback arbitration for integer/vector units
Focus: keep control hazards predictableEvidence matrix
RISC-V EVIDENCE MATRIX - Five-Stage Pipeline Partitioning and Timing Contracts
+--------------------------+--------------------------------+--------------------------------+---------------------------+
| Evidence | Tells you | Does not prove | Next action |
+--------------------------+--------------------------------+--------------------------------+---------------------------+
| perf counter timeline | where regression appears | exact mechanism causality | correlate with trace |
| decode/control dump | control intent per instruction | pipeline side-effect ordering | inspect retire semantics |
| trap + CSR logs | privilege/fault behavior | performance bottleneck alone | pair with CPI buckets |
| MMU/TLB walk trace | translation behavior | full system QoS impact | test mixed workloads |
| post-fix trend graph | movement after fix | long-term stability | run stress matrix |
+--------------------------+--------------------------------+--------------------------------+---------------------------+Capture baseline and failing traces under fixed metadata tags.
Classify stage loss and dominant mechanism.
Collect Stage-contract specification with pipeline register map and valid/kill timing waveforms for all instruction classes..
Apply one bounded fix with owner signoff.
Run validation matrix and decide ship/rollback.