The 2 GiB/card that \`rocm-smi\` shows free is not idle: the engine's budget
table calls it driver context + the 896 MiB activation arena + 96 MiB headroom,
and says the rest is `throughput on the floor`. Its own settle line is the
number that matters — `card 0 settled at 2.01 GiB free against 209.19 MiB (the
96.00 MiB --gpu-headroom-mib and 113.19 MiB kept for the static region)` — so
1,849 MiB above the ENGINE's floor is claimable and the real ceiling is 30,969
MiB, not the 29,120 my 1 GiB reserve invented on 2026-10-11.
Shipped pair 25600/5120 = 30,720: +1,600 MiB of slab, ~458 MiB above the floor.
The slab is already saturated at 24,000 (mover took all of it, 451 KiB slack),
so this is the only direction left — KV is at its 3-slot floor (5,063 needed of
5,120).
Named prediction, because today's two points say the slab is a THRESHOLD and not
a slope (22,208 -> 3,397 t/s, 24,000 -> 3,290 t/s at 43.5k single-stream): this
arm buys ~1,600 resident expert slots and ~0 prefill. The point that moves
prefill is 26,071 (2026-10-11: 4,379 t/s), fundable only at two slots. Prefill
moving > +-3 % here falsifies the threshold reading.
Seam: the ceiling gate now derives from the engine's budget table (30,969) and
is the single owner of the pair arithmetic; the duplicate I put in the shape
test is removed.
Frank
09a0251d2d