Audit of all disk I/O paths in the engine (expert pread, KV persistence,
config/tokenizer loads) and research into techniques used by llama.cpp,
vLLM, AirLLM, PRESERVE, HOBBIT, SolidAttention. Findings:
- Expert path is already well-batched (one coalesced ~19MB O_DIRECT pread)
- 76% of decode time is expert-disk I/O on RAM-constrained hosts
- posix_fadvise(WILLNEED) is a no-op on Windows (compat.h:107)
- I/O-to-compute ratio is 3.6x — the binding constraint
- Levers: hit-rate (cache cap), cross-layer prefetch (PILOT_REAL),
storage (VHDX vs direct NVMe), batched decode
Ranked opportunities and source links documented in issue_diskio.md.
woolcoxm