VRAM: ray-tracing working buffers (rt-aux 643 MB) sized for the worst case #161

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opened 2026-09-29 05:49:02 +00:00 by sky_line · 0 comments

sky_line commented

2026-09-29 05:49:02 +00:00

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VKMem breakdown in a busy two-sim view: rt 403 ... as 944 (51466 blas) rt-aux 643. That's ~2 GB for ray tracing, of which 643 MB is auxiliary (build scratch, TLAS instance / geometry tables, rig position buffer, used-bit readbacks).

These look sized for the maximum rather than the live need:

TLAS capacity is 491,520 instances vs ~40-100k active.
Scratch is grown to the largest frame's builds and kept.

Check / fix

Size the TLAS instance / rt_geom tables and the TLAS itself from active instances (the pass-A compaction count), not buffer capacity. Grow with headroom and shrink when far over.
Bound scratch: split large build batches across frames rather than one scratch big enough for all of them.
Review the 944 MB of BLAS: ~45k static BLAS at the 768 MB budget. Check the compaction hit rate, and whether distant or small objects need BLAS at all within RenderVKRTRadius.
Break the rt / rt-aux lines into their parts in the VKMem log so regressions are visible.

Refs #157.

VKMem breakdown in a busy two-sim view: `rt 403 ... as 944 (51466 blas) rt-aux 643`. That's ~2 GB for ray tracing, of which **643 MB is auxiliary** (build scratch, TLAS instance / geometry tables, rig position buffer, used-bit readbacks). These look sized for the maximum rather than the live need: - TLAS capacity is 491,520 instances vs ~40-100k active. - Scratch is grown to the largest frame's builds and kept. ## Check / fix - Size the TLAS instance / rt_geom tables and the TLAS itself from **active** instances (the pass-A compaction count), not buffer capacity. Grow with headroom and shrink when far over. - Bound scratch: split large build batches across frames rather than one scratch big enough for all of them. - Review the 944 MB of BLAS: ~45k static BLAS at the 768 MB budget. Check the compaction hit rate, and whether distant or small objects need BLAS at all within `RenderVKRTRadius`. - Break the `rt` / `rt-aux` lines into their parts in the VKMem log so regressions are visible. Refs #157.

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2026-09-29 06:00:00 +00:00

VRAM: ray tracing must fit a VRAM-scaled budget, below textures (8 GB cards starve) #164

sky_line referenced this issue

2026-09-29 06:00:00 +00:00

Textures on avatars are slow to load/Don't load at all/Low in super low Res #145

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2026-09-29 08:06:43 +00:00

RT working buffers: size from live need, scratch budget, shrink when oversized

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2026-09-29 08:06:43 +00:00

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