The experiment guest-frame-rate-WITHDRAWN.md named. A triple buffer
rotating once per present visits the same three base addresses whether or
not anything was decoded into them, so base identity cannot separate
"decode per present" (30 fps guest, 60 units/s) from "rotate per present"
(60 fps guest, 120 units/s). A content hash can.
command_processor.cc now emits h=<FNV-1a over 4096 sampled bytes> beside
every sampled texture, omitted rather than faked when the address does not
translate, so a missing hash cannot read as a matching one. Incremental
build, one translation unit.
Predictions committed before the capture: consecutive presents with changed
luma content is ~1.00 under decode-per-present and ~0.50 under
rotate-per-present, with acceptance bands and "neither" reported rather
than rounded.
The control is the part I got wrong last time. A STATIC texture must hash
constant: the splash sprite page 0x11A50000 is a fixed atlas, and if its
hash varies between presents then reading guest memory at draw time races
the decoder and nothing in the log may be read. That fails loudly in the
direction which would otherwise manufacture the answer I previously
reached -- the property my last control lacked. A second control in the
other direction requires the movie luma hash NOT to be constant, which
would mean hashing the wrong bytes and would manufacture the opposite
answer.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Jc4pciRArGHfxGGhEbwp5t
56ae05a18b