RISC-V Design · All levels
Pipeline Performance and CPI Decomposition: Expanded Case Study
Expanded Case Study for Pipeline Performance and CPI Decomposition.
Expanded case study
Expanded Case Study for Pipeline Performance and CPI Decomposition is anchored on Measured CPI broken into ideal base CPI, structural stalls, data stalls, control stalls, and memory wait contributions.. Convert observations into mechanism-backed decisions with explicit ownership.
Use this page to rehearse complete review flow: symptom intake, mechanism split, evidence request, owner assignment, bounded fix, and closure decision.
Root-cause tree
diagram
ROOT CAUSE TREE - Pipeline Performance and CPI Decomposition
Measured CPI broken into ideal base CPI, structural stalls, data stalls, control stalls, and memory wait contributions. 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.Evidence matrix
diagram
RISC-V EVIDENCE MATRIX - Pipeline Performance and CPI Decomposition
+--------------------------+--------------------------------+--------------------------------+---------------------------+
| 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 |
+--------------------------+--------------------------------+--------------------------------+---------------------------+