pin_load computed npin from the RAM budget FIRST, then carved the
VRAM-ranked prefix out of those npin slots. With CUDA_RELEASE_HOST the
prefix's host slabs are freed right after upload — so on a multi-GPU
host the top-ranked experts consumed the RAM budget without occupying
RAM, and the CPU tier pinned only the leftovers. Measured on 6x RTX 5090
(251 GB): 9,280 VRAM + only 1,721 RAM pins (32.5 GB warm) on a box whose
RAM fits ~10k more — the cold tail then paid disk on every token and the
hit rate ceilinged at 99.0% forever.
Move the VRAM budget estimate above the npin finalization and make the
release-destined prefix ADDITIVE to the RAM-derived count. Same box,
same env plus the fix:
[PIN] placement: 9,280 VRAM + 10,176 RAM (192.5 GB warm)
expert hit rate 100.0% (pin 100.0% + lru 0.0%) — disk 0
1,024-token greedy decode: 3.62 -> 6.21 tok/s (+72%)
warm late segment (t=768-1024): 5.11 -> 5.73 tok/s (+12%)
prefill: 10.4 -> 8.8 s
The whole-run gain is the LRU warmup penalty disappearing (full
residency from the first token); the late-segment gain is the steady
~0.9%-miss disk residue recovered. Non-release configs are untouched:
prefix_est stays 0 and the arithmetic reduces to today's exactly.
ZacharyZcR
453d1401ba