Two strands bundled as the 1H-codesign-paper refresh unit:
(A) This session — single-op cost-model reflection (depends on 2d8271c):
- §2 Table 2 (tab:hw): split "FIXED per command" into "FIXED per
single-op command" (8 cycles) and "FIXED per composite command"
(40 cycles); §2 dispatch-overhead prose updated to the two-class split.
- §3.4 (sec:gemm-vs-async): rename paragraph headers + prose to
async-full / async-tiled; "atomic" -> "single-op" throughout; reframe
mechanism #3 from the old DMA-only fast-path to the single-op
fast-path. Headline narrative now: even with EVERY single-op cmd
(96 DMA + 48 dot + 47 add) charged the light 8-cycle FIXED, composite
still wins ~2.8x at K=3072 purely on command-count structure (1 vs
192 commands) -- down from the pre-D8 ~6.3x, and explicitly NOT a
modelling artifact. Numbers refreshed from the regenerated sweep:
async-full 3.83->3.91, async-tiled 1.14->~2.53, under-tile corner
1.06->1.21, depth-2 vs depth-inf spread <1%. New figure wired in.
- build/main.pdf rebuilt (tectonic); pdftotext-verified (no broken
refs; Table 2 split, single-op terms, 2.8x/2.53/192-host-commands
all present).
(B) Prior-session paper work riding along uncommitted: §4 all-reduce
deep-edit, §5 GQA, §6 discussion trims; milestone_1h_ccl.py plot
label "FSIM" -> "H2 2025 SW queue baseline"; regenerated diagrams
under docs/diagrams/** and gemm output PNGs under
1H_milestone_output/gemm/. (Composite-window gemm plots are
unaffected by D8 — D8 only changes single-op dispatch FIXED, which
the composite window excludes.)
All TODO items for the D8 single-op extension are now complete and
pushed across 3 commits (2d8271c cost-model+ADR+tests, 821bbf2 bench
harness, this paper refresh). Full regression green (826 passed, 1
skipped). No remaining work.
NOTE for review (carried from 2d8271c): ADR-0065's "2x CPU-offload win"
headline for GQA decode opt2 may want a refresh to the post-D8 ~1.87x.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Mirror the sccl pattern for GEMM figures: a tests/gemm/ package renders the
GEMM bar charts as PNGs from the committed docs/diagrams/gemm_sweep.json, so
the figures are fast test artifacts (run by default) while the heavy sim sweep
stays a manual script (scripts/gemm_sweep.py, kept) wrapped by a slow
regenerator test.
tests/gemm/:
- _gemm_plot_helpers.py: matplotlib renderers (series logic mirrors the
GEMM _render_* functions in scripts/build_overview_slides.py).
- test_plot_gemm_stage_breakdown.py: gemm_stage_breakdown.png (load_ref).
- test_plot_gemm_mac_utilization.py: gemm_mac_utilization_measured.png +
gemm_mac_utilization_theoretical_vs_measured.png (load_ref).
- test_gemm_sweep.py: @pytest.mark.slow regenerator (runs scripts/gemm_sweep.py).
Chart set trimmed to three (stage breakdown, MAC util, theoretical-vs-measured);
"formula" relabeled to "theoretical" throughout the comparison chart.
Known follow-ups (not blocking):
- gemm_mac_utilization_measured.png currently plots the theoretical ideal-
pipeline model, not simulator-measured data; the name is a misnomer pending
a decision to repoint its content or retitle.
- The theoretical-model constants (HBM 256 GB/s, T_stage 16 ns, 3 stages) are
inherited verbatim from build_overview_slides.py and not yet verified against
ADR-0033 / ADR-0014 / topology.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
ywkang
mukesh