The game waits each frame until the GPU has finished the frame before. In Hyrule Field with FSR 4 the last of that
work is one part of 4.7 ms, the temporal upscaler and the interface drawn after it, then 1.4 ms of write-backs, and
what the game reads of the frame is done before the upscaler runs. With NX2NAVI_TAIL_EARLY the replay records that
tail into a command buffer of its own, and when it hands the CPU nothing but timestamps, writes no pool memory but
inline uniform updates of mirrored blocks and reads no guest memory late, the write-backs go to the queue before it
with the executed timeline's signal. The game's waits end there, and the GPU runs the tail while the next frame is
prepared. The GPU's commands are the same; a tail that fails a test goes as before. Off by default.
RX 7900 XT, Ryzen 7 5800X3D, 3440x1440, FSR 4 Native AA, one batch, replay workers off: 50.7 against 42.5 fps
standing and 56.0 against 45.9 along the field route; with FSR 3.1, 51.8 against 47.8 and 54.9 against 52.3. With
three replay workers, FSR 4, standing: 63.5 against 49.4. The screenshots matched those without it standing, along
the route and through warps to five areas, with no black frame outside the loading screens of both.
Co-Authored-By: Claude Fable 5.2 <noreply@anthropic.com>
Every frame the render thread waited about 5 ms for the GPU after the frame's first submission, with the game
CPU-bound in every area. The wait is there so that the GPU has run that submission's passes before the game
rewrites what they read. But the submission also ends with the write-backs of what its shaders wrote, 60 MiB merged
into guest memory in 3 to 4 ms of GPU time, and the wait covered those too.
The write-backs now go into a part of their own. The part before them signals a second timeline, the executed
timeline, and the first-submission wait waits on that; the write-back part signals the timeline as before, so every
fence the game asks for still covers them, in the same queue order. wb_split = 0 keeps one part and the old wait.
Not measured in the game yet.
Co-Authored-By: Claude Fable 5.2 <noreply@anthropic.com>
Comments say what the code does and why, docs/maxwell.md keeps the Maxwell facts, and fetch_refs.sh clones only the checkout the build reads. Code is unchanged.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
