The ingest term was 90 bytes per reflection and 64 per run. Measured with cudaMemGetInfo at each
step of IngestUpload/IngestSort (relative to the free memory before the observation arrays):
- the second radix sort is the peak where runs are few: the 66 B of observation arrays, by_image,
perm, key, key_sorted and cub's alternate key/value buffers of a plain SortPairs - 102.3-103.0 B
per reflection on 7qij (51.1 M, 52.2 M, 78.1 M reflections) and 4nwv (32.7 M);
- the cut is the peak where runs are many: 98 B per reflection plus 56 per run (4nwv, 15.4 M runs:
125.8 B per reflection, 4106 MB against 3923 MB from the old formula);
- the upload holds the 66 B beside the two 64 MB staging buffers (~150 MB measured).
Now max(103 B per reflection + 58 B per run, 66 B per reflection + 160 MB): 2-4% above every
measured peak, where the old formula was 10% under on 7qij (7170 MB against 7986 MB for the main
engine) and 4.5% under on 4nwv. Its only consumer is whether the all-observation arm goes beside
the main engine, which changes when that merge runs, not what it gives.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EizBKhTqrAYago9KJG3dA3
leonarski_fandClaude Opus 5.5
b736c4cefb