RISC-V Design ยท All levels
Page Fault Handling, Trap Flow, and Recovery Paths: Worked Example
Worked Example for Page Fault Handling, Trap Flow, and Recovery Paths.
Worked example
Worked Example for Page Fault Handling, Trap Flow, and Recovery Paths is anchored on Fault service latency (median/P99), restart success rate, and throughput impact during demand paging and copy-on-write stress.. Convert observations into mechanism-backed decisions with explicit ownership.
A regression flags Fault service latency (median/P99), restart success rate, and throughput impact during demand paging and copy-on-write stress.. Strong closure isolates first failing mechanism, proves causality, applies one bounded change, and validates blast radius.
System view
RISC-V PIPELINE DIAGRAM - Page Fault Handling, Trap Flow, and Recovery Paths
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 - Page Fault Handling, Trap Flow, and Recovery Paths
+--------------------------+--------------------------------+--------------------------------+---------------------------+
| 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 Fault lifecycle sequence from exception entry to TLB shootdown and instruction replay, including nested page-fault cases..
Apply one bounded fix with owner signoff.
Run validation matrix and decide ship/rollback.