Three coupled fixes so enable_data=False now reports byte-identical
kernel-body sim latency (max(t_end) - min(t_start) over op_log) as
enable_data=True, and skips setup-write sim events that were pure
wall-clock overhead.
Before this change, at Case 4 (Cube-SP x PE-SP) decode, S_kv=8K:
enable_data=False -> latency_ns = 0 (op_log empty)
enable_data=True -> latency_ns = 30.646 us (correct)
After:
enable_data=False -> latency_ns = 30.646 us (byte-equal)
enable_data=True -> latency_ns = 30.646 us (unchanged)
engine.py: always create OpLogger. Previously OpLogger was gated on
enable_data=True together with MemoryStore, so op_log stayed empty when
data mode was off. Decouple: MemoryStore is gated (Phase 2 DataExecutor
still needs it) but OpLogger runs unconditionally, receiving
memory_store=None when data mode is off. OpLogger already guards its
arr.copy() snapshot paths on `if self._memory_store is not None`.
pe_cpu.py: always use the ADR-0020 greenlet execution path. The
if store is not None: _execute_greenlet(); else: _execute_legacy branch
gated the *execution model* on data-mode presence. The legacy
command-list path predates ADR-0020 and doesn't route IpcqSendCmd
through PE_IPCQ (it goes to PE_SCHEDULER instead), so all 189 Case-4
ipcq_copy fabric transfers were silently no-op'd in that mode. Forcing
greenlet gives identical sim behavior in both modes. KernelRunner
already guards its store reads on `self._store is not None`.
context.py: gate setup MemoryWriteMsg on memory_store presence. Under
enable_data=False there is no MemoryStore to populate and no Phase 2
replay, so the per-shard sim events for Q/K/V deploy are pure wall-clock
overhead with no effect on reported kernel latency (Yangwook's max-min
formula excludes pre-kernel ops). Handle count for Case 4 at S_kv=8K
drops 229 -> 37 under enable_data=False.
Verified:
- tests/attention/test_milestone_gqa_decode_long_ctx_4cases.py: 18/18 pass
- Parity probe: enable_data=False/True both report 30.646 us kernel sim
time, 1649 op_log records, 189 ipcq_copy events
Known follow-up: pe_cpu._execute_legacy is now dead code but left in
place; separate cleanup once we confirm no downstream caller.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
New tests/analytical_visualization/ module - an interactive dashboard
for exploring memory / latency tradeoffs of transformer inference on
the SIP architecture.
Highlights:
- 30+ model presets (Qwen, Llama 2/3/3.1, Mistral, Gemma 2, Phi 3,
DeepSeek MLA, Mixtral/Qwen 3 MoE, Grok-1, ...)
- Placement toggles: TP and CP each on PE-level vs cube-level
- CP ring variant: K/V ring vs Q+O/m/l ring (prefill); in decode the
O/m/l all-reduce is folded into S8 (no separate C1 row)
- SIP interconnect: ring / mesh2d / torus2d with matching link drawing
- Per-stage latency table with compute + memory + comm formulas,
auto-scaled ns/us/ms, colored by dominant bound
- Ring attention loop indicator on the pipeline diagram (purple arc
over S5-S8 with 'xN hops' badge)
- Tensor sharding view with optional physical PE/cube annotations
- Replication-waste + optimization-hints panel
- Save & compare configurations (config1, config2, ...): summary table
plus side-by-side per-stage attention and FFN latency, best-in-row
highlighting
- Symbol glossary with current values for every symbol used in formulas
Not tied to production sim_engine or runtime API; purely analytical
tooling for design-space exploration.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Both 1-kv (2 users x 64 PE) and 8-kv (16 users x 8 PE) fill all 128 PEs of
the SIP; the throughput gap is per-PE HBM efficiency. Splitting a head over
8 PEs leaves each a single tile, so pipeline-fill and the 8-PE softmax
reduce dominate -> 46% HBM util; one head per PE streams contiguously with
no reduce -> 76%. Throughput ratio (1.6x) tracks the utilization ratio
(1.7x): decode is bandwidth-bound, so throughput follows total HBM
efficiency, not PE count. 1-kv spends hardware on latency (8 PE/head for a
4.8x speedup = 60% strong-scaling efficiency).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Beyond a mapping's SIP capacity (16/C) the throughput plateaus: extra
users run in waves at the saturated rate, they are not un-runnable. Draw
a dashed horizontal extension at the ceiling so 1-kv-per-cube (cap 2)
reads as saturating, not stopping, at B=2. Caption updated.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Concurrency fix (completes the cube_base change): the decode kernel's
output store o_base still used the global cube_id while every load used
the user-local cube_local. For a single user (cube_base=0) they coincide,
so it was masked; a second batched user (cube_base>0) overshot its o shard
into an unmapped VA, mis-decoded to a phantom sip0.cube0.pe8 and raised a
RoutingError. Switch o_base to cube_local (one line); single-user results
are byte-identical (decode smoke/correctness pass).
Batch harness (un-skipped): create all users' tensors first, then submit
all launches deferred and drain together, so deploys don't drive an
already-submitted launch and serialize the batch. Concurrent users on
disjoint CUBE groups now overlap to within 3-5% of the single-user
latency. Swept B in {1,2,capacity} at 8K (high-B dense runs are the
expensive ones; throughput is near-linear in B).
Measured result: aggregate throughput at a full SIP rises from 0.86
(1-kv-per-cube, 2 users) to 1.41 requests/us (8-kv-per-cube, 16 users) —
the dense mapping wins throughput, the spread mapping wins latency.
S5.2 batch paragraph updated projected -> measured; add batch_scaling
figure and plot_batch_scaling.py.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Metric fixes (test harnesses, deploy artifact + wrong constant):
- wall = max(t_end) - min(t_start): exclude the one-time KV-cache deploy
from the measured decode/prefill step (it was 92-99% of wall, mapping-
invariant, and masked the real per-mapping separation).
- PEAK_PE_HBM_BPS 128 -> 256 B/ns (8 channels/PE x 32 GB/s); the old value
was half the modeled per-PE HBM BW, so hbm_bw_util read >1.0 once wall
was corrected. All six short-context sweep CSVs regenerated/repatched.
Result: the four KV mappings now separate along a {64,32,16,8}-active-PE
ladder (decode 8-kv/1-kv = 4.8x at 8K, 7.4x at 64K), not "modest/tied" as
before; decode is bandwidth-bound at 46-76% of the 256 GB/s per-PE ceiling.
Report (S5.2 rewrite):
- Replace the tied-wall / 8x-per-PE-util claims (both deploy artifacts)
with the corrected separation and a density trade-off (per-CUBE KV
footprint, Fig 16 top panel switched to a wall-invariant metric).
- Add a projected latency-vs-batched-throughput analysis (marked
projected, not measured): dense mappings win throughput, 1-kv wins
latency; converges at long context.
- Regenerate Fig 15/16/17/18; fix plot script hardcoded ROOT path.
Batch experiment (Part 2, cube_base):
- Add backward-compatible cube_base=0 scalar to the decode kernel so a
batched user placed at DPPolicy.cube_start addresses 0-based shards.
Default preserves single-user behavior (32 decode tests pass unchanged).
- New batch harness (skipped): concurrent B>=2 launches hit a sim routing
issue (sip0.cube0.pe8); single-user path verified. Concurrency fix next.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
- Soften short-context claim: 1-kv-/8-kv-per-cube are tied at 8K and
separate as context grows (1-kv faster at the large end).
- Add a bridge noting the six-case placement taxonomy (§5.1) is the
long-context lens; short context turns on head-to-CUBE distribution.
- Remove caption-duplicating numbers from the long-context conclusion.
- Reduce the closing subsection to a GQA-scoped Summary; defer the
cross-cutting hardware-investment thesis to the Discussion.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Make reduce_mlo derive its submesh dimensions (sub_w, sub_h, root_col,
root_row, root_cube) from C at call time, with peer-existence guards on
every inter-cube send/recv so any C ≥ 1 completes cleanly (previously
hardcoded to C=8's 4×2 mesh; non-rectangular C like 7 or 12 hit
IpcqDeadlock at the root cube's east receive). Byte-equal at C=8 —
existing composite digest tests still pass 8/8.
Callsites in the four Case-6 kernels (primitive / primitive-tiled /
composite / composite_extended) updated to pass C into reduce_mlo and
use root_cube_for(C) for the final tl.store gate.
Add the multi-model attention bench: sweeps the composite kernel at
S_kv=128K across six GQA models (Gemma-2 27B, LLaMA-3 8B, Qwen 2.5 7B,
LLaMA-3 70B, Qwen 2.5 72B, Command R+), with per-model topology
C = h_q (cubes per KV group = query heads per KV group). Captures
per-op-kind occupancy (matmul GEMM+MATH, comm DMA) alongside latency
and PE_CPU dispatch. Three-panel plot writes to bench-output and
paper-figures dir.
Headline result: same-h_q-different-family models land within 0.2 µs
(model-agnostic given fixed h_kv=1 per KV group + d_head=128); latency
climbs 263 → 492 µs as C climbs 2 → 12, driven by reduce depth
(comm/matmul ratio 0.4 → 0.6 across the sweep).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Switch primitive hand-tiled Q·Kᵀ / P·V from a deferred-K-sum tl.dot
chain to per-block GemmCmd writes into a shared (M, N) out handle
(implicit MAC-side accumulation). Full-shape coarse Q / K_T / V loads
carry data-mode correctness; per-block DMAs remain for the streaming
architecture dispatch story. The kernel now runs in engine mode
end-to-end, so its 128K latency is measured instead of derived as
primitive + Δdispatch. Drop the coarse-primitive baseline from the
sweep and plots; keep the kernel file for reference.
At S_kv=128K: primitive hand-tiled = 959.5 µs vs composite = 460.7 µs
(2.08× from 5 235 vs 94 PE_CPU commands).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Wires a fourth variant into the Cube-SP × PE-SP long-context decode
composite command-form study to surface the worst-case PE_CPU dispatch
inflation that the coarse composite forms delegate to PE_SCHEDULER
(ADR-0065): per-block DMA of Q/K/V slices, tl.dot per 16³ block,
deferred K-inner sum outside the K loop.
Renamed _tiled.py → _hand_tiled_16x16x16.py; coarse-primitive kernel
retained for the 4-cases bench, paper scripts, and the golden byte-equal
regression guard.
New breakdown bar chart at S_kv=128K shows engine (~460 μs) dominates
all three variants; hand-tiled adds ~68 μs PE_CPU dispatch on top —
composite forms sit essentially on the memory-bound floor.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Research artifact (NOT wired into the production sweep) for the decode composite-vs-primitive investigation. Models a primitive decode kernel that hand-blocks each tl.dot into 16x16x16 GemmCmds, charging per-MAC-block PE_CPU dispatch -- testing whether faithfully charging the dispatch that the composite form offloads to PE_SCHEDULER flips the 'composite gives no decode latency benefit' result.
Finding: it does NOT. Even with up to 512 serialized blocking GemmCmds per matmul (vs 2 coarse tl.dot), end-to-end decode latency is unchanged (8192: 28.9us, 32768: 114.9us) -- the inter-cube (m,l,O) reduce DMA tail dominates and the local-attention GEMM/dispatch sits in critical-path slack. Confirms the two-regime conclusion (24c7054): composite helps compute-bound prefill, not memory/reduce-bound decode.
Caveats: measured at S_kv 8K/32K (reduce-dominated); large-S_kv streaming regime extrapolated only. The -5.5% tiled<untiled is reduce-tail ordering noise, not fully nailed down.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Complete the composite-command study across both attention regimes and
write up the result, resolving when the composite command helps latency.
Decode (memory-bound, T_q=1, M=8): the command form is latency-neutral —
the kernel is bound by KV streaming and the MAC array is near-idle, so the
composite's only benefit here is host-issue offload (O(n_tiles) -> O(1)
PE_CPU commands). Figure: gqa_decode_long_ctx_composite (latency flat,
command count saturates).
Prefill (compute-bound, large M=G*T_q tile-filling): add three command-form
variants of a single-rank FlashAttention prefill kernel
(_gqa_prefill_compute_bound: primitive / composite / composite_extended).
Here the composite's scheduler-internal per-tile DMA<->compute pipeline
keeps the MAC array fed while the primitive's blocking tl.dot starves it,
so composite wins on MAC utilization (68% flat -> 83%) and wall-clock
(19% faster at ctx=1024), with the margin growing with context (deeper
P.V reduction = more tiles to pipeline) — the compute-bound mirror of the
GEMM result in section 3. Figure: gqa_prefill_compute_bound (latency +
MAC util). Sweep wired as GQA_1H_SWEEPS=prefill_cb; tests cover structure,
e2e, and composite<primitive in the compute-bound regime.
The synthesis: composite has two benefits set by roofline position —
host-issue offload (always) and MAC-array feeding (compute-bound only).
Decode exercises the first, prefill both.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Add two command-form variants of the Case-6 (Cube-SP x PE-SP) long-context
decode kernel alongside the primitive baseline:
- composite: per-tile GEMMs issued as one coarse tl.composite over the
full S_local (PE_SCHEDULER tiles/streams K,V) -- O(1) PE_CPU commands
vs the primitive kernel's O(n_tiles).
- composite_extended: Q.K^T composite + softmax_merge recipe composite
(ADR-0065), folding the per-tile online merge + P.V.
Extract the shared two-level (m,l,O) reduce into _gqa_mlo_reduce and
refactor the baseline to use it (byte-equal, guarded by a 64-rank
command-stream digest test).
Engine fix: _make_compute_out omitted pinned=True, so an on-chip TCM
compute result consumed as a composite GEMM operand was scheduled as an
HBM DMA_READ of its bit-61 scratch address -> PhysAddrError in data mode.
Mark compute outputs pinned (resident), matching the composite
auto-output and recipe scratch handles. .pinned is read only by the
tiling DMA gate, so this is byte-equal for existing benches.
Add the composite sweep (emit-level PE_CPU dispatch to 1M + data-mode
latency to 128K), its plot, umbrella wiring (GQA_1H_SWEEPS=composite),
and tests (refactor guard, dispatch saturation, engine-fix, e2e).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
- §6 GQA: rewrite long-context decode from 4-case to 6-case. Data
Placement Policy now presents the six placement options and their
intrinsic per-PE memory / per-token comm costs (no winner predicted);
the long-context subsection selects the best placement for that regime
(Case 6 ★, both-axes S_kv shard) from the measured 6-case sweep. Add
KV-sharding diagram + analytical budget/summary figures.
- Regenerate the 6-row decode sweep (milestone-1h-gqa) and the
sweep-dependent decode panels (latency/traffic/parallelism/memory) so
figures, prose, and sweep_decode.json are mutually consistent.
- §5 All-Reduce: add IPCQ design alternatives (architecture + decision
matrix) as design-rationale schematics (illustrative step-counts, not
measured) and the bench-generated topology diagram.
- §4 GEMM: rename "user-orchestrated/user-level" -> "kernel-orchestrated/
kernel-level" (orchestration runs in the kernel program vs the
scheduler-orchestrated composite); minor accuracy fixes (7.18 TFLOP/s
~10% below peak; ~781 ns DMA).
- Recompile build/main.pdf.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Replaces the unsourced 32 KB/layer placeholder in the analytical chart
with T*(N-1)/N where T = h_q * S_q * (d_head*2 + 8) ~ 2.1 KB
(per-PE (m, l, O) payload) and N is the participant count of the
reduce-only chain per stage. Cases 2/3/6 analytical bars now match
the simulator-measured numbers within ~10% (was 6-30x over).
Also:
- Bumps the measurement S_kv from 8 K to 64 K to verify Cases 1, 2, 3, 6
are genuinely S_kv-independent and Cases 4, 5 scale linearly.
- In-bar descriptor on the paired chart is now wrapped to fit the bar
width, black, no background box, and centered between the analytical
and measured bars so the label applies to both.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Drops the per-case panel outline from linewidth 2.2 to 0.9 with 85% alpha.
The case-color frame still anchors each panel but no longer competes
with the swimlanes, flit packets, and annotations inside.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Adds two new IPCQ architecture views in the latency_model.png aesthetic:
a 2x2 flow figure (one per case) and a 4x1 stacked figure for taller
horizontal panels. Refactors per-case panel drawing into shared helpers
and disambiguates the flit labels (HMQ desc -> Hd so it does not
collide with data D). Two-row legend keys.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Drops the control-data overlay from the paper figures folder and
adds the per-send latency cycle-stack PNG instead.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Removes the (measured) comm column, widens the Notes column with
shorter wrapped text, scales the table figure down, and wraps the
heading to two lines so it sits flush with the table.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
6 generated figures comparing IPCQ (chosen) against the 3 HW alternatives
(Doorbell+Polling, HMQ, RDMA-CQ): architecture blocks, latency stack,
op counts, sequence flow, decision matrix, and control/data plane overlay.
Three figures also copied into the paper's figures/ folder for inclusion.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
The previous commit (8102ddb) renamed the figures-dir
gqa_decode_long_ctx_4cases_*.png → 6cases_*.png but only the rename
was staged; the cp that brought the regenerated 6-case content
landed after `git add`, so the committed bytes were still the old
4-case ones. This commit syncs the bytes.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Filename cleanup so every long-ctx GQA artifact has a consistent
"gqa_long_ctx_6cases_*" prefix (or "gqa_decode_long_ctx_6cases_*"
for decode-only charts). Old "4cases" / mixed names retired.
Renames (long_ctx + figures, content unchanged):
gqa_hbm_budget.png -> gqa_long_ctx_6cases_hbm_budget.png
gqa_4cases_summary.png -> gqa_long_ctx_6cases_summary.png
gqa_4cases_memory_comm_analytical -> gqa_long_ctx_6cases_memory_comm_analytical.png
gqa_4cases_memory_comm_paired -> gqa_long_ctx_6cases_memory_comm_paired.png
gqa_kv_sharding_6cases_diagram -> gqa_long_ctx_6cases_kv_sharding_diagram.png
gqa_kv_sharding_6cases_table -> gqa_long_ctx_6cases_kv_sharding_table.png
gqa_3cases_measured_comm.json -> gqa_long_ctx_6cases_measured_comm.json
gqa_decode_long_ctx_4cases_*.png -> gqa_decode_long_ctx_6cases_*.png
(figures dir; long_ctx never had old)
New 4-chart 6-case set in long_ctx output dir (regenerated by
paper_plot_gqa_decode_long_ctx_4cases.py, which now reads all 6
sweep_decode.json panels — Cases 1-6 with the same colour scheme
used elsewhere: red = overflow per-PE HBM, grey = neutral, blue
= Pareto-best ★):
gqa_decode_long_ctx_6cases_latency.png
gqa_decode_long_ctx_6cases_memory.png
gqa_decode_long_ctx_6cases_parallelism.png
gqa_decode_long_ctx_6cases_traffic.png
Generator scripts updated to write the new filenames + handle the
two new d_head-TP variants (Cases 4, 5) in their per-PE memory and
active-PE-count helpers. Figure widths bumped 10 -> 12 in to fit 6
multi-line case labels.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Two new long-ctx decode attention kernels for the d_head-TP sharding
variants the 6-case chart predicts:
· _gqa_attention_decode_long_ctx_cube_sp_pe_tp_dhead.py
Cube-SP × PE-TP-d_head (Case 4 in chart). Per cube holds
S_kv/C tokens of full d_head; per PE holds same tokens but
only d_head/P dims. Partial Q·Kᵀ scores reduced intra-cube
before softmax; outer (m,ℓ,O) merge two-phase (intra+inter).
· _gqa_attention_decode_long_ctx_cube_tp_dhead_pe_sp.py
Cube-TP-d_head × PE-SP (Case 5). Per cube holds full S_kv
with only d_head/C dims; per PE holds S_kv/P of those dims.
Partial scores reduced inter-cube (UCIe) before softmax.
Sweep dispatch (gqa_decode_long_ctx_4cases.py) extended with two
new panels so the milestone-1h-gqa sweep covers all 6 cases.
Smoke test scripts/verify_case4_dhead_tp.py runs Cases 4/5/6 at
S_kv=2K to validate the kernels load and execute end-to-end.
Plus the figure-generation toolchain that produced the committed
PNGs in the prior commit (dd3337f):
· paper_plot_gqa_4cases_summary.py - 3-panel summary +
2-panel (analytical / paired-measured) chart generator.
_plot_comm now takes mode="analytical" | "paired".
· paper_plot_gqa_kv_sharding_diagram.py - 6-case 2-D KV-tensor
diagram + companion comparison-table PNG.
· measure_gqa_decode_placement_comm.py - runs all 6 kernels at
S_kv=8K, sums actual IPCQ-copy bytes from engine.op_log,
scales partial-score AR ×128 to S_kv=1M, writes
gqa_3cases_measured_comm.json (committed).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Six PNGs covering the 6-case decode KV-placement story, copied
into both the kernbench 1H_milestone_output staging dir and the
1H-codesign-paper figures/ dir:
· gqa_hbm_budget.png - per-PE HBM budget bar
· gqa_4cases_summary.png - 3-panel: HBM + KV mem + comm
· gqa_4cases_memory_comm_analytical - 2-panel: KV mem + comm (analytical)
· gqa_4cases_memory_comm_paired - 2-panel: + measured overlay
· gqa_kv_sharding_6cases_diagram - 2-D KV-tensor view (Y=S_kv, X=d_head)
· gqa_kv_sharding_6cases_table - companion comparison table
The original 4-case gqa_4cases_summary.png is updated to the new
6-case 3-panel layout. Generator scripts and Phase-1 d_head-TP
kernels remain untracked - separate commit scope.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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>
Adds the user-orchestrated async GEMM variants used in paper §3.4 to
contrast with the composite (load_ref) path:
- matmul-async : naive (tl.load full A+B, one tl.dot)
- matmul-async-chunked : depth-inf prefetch (all B-tiles queued)
- matmul-async-chunked-db : depth-2 double-buffer (TCM-bounded)
plus scripts/paper/paper_plot_gemm_async_vs_composite.py (4-way per-PE
TFLOPS sweep + figure) and the regenerated outputs under
1H_milestone_output/gemm/.
Sweep regenerated under the ADR-0064 D8 single-op cost model (commit
2d8271c). At K=3072 the composite-vs-async-tiled gap narrows from the
pre-D8 ~6.3x to ~2.8x (composite 7.18 / async-tiled 2.54 TFLOPS): D8
makes the async-tiled kernel's ~191 single-op dispatches 5x cheaper, so
its dispatch overhead drops to ~1.5us. Qualitative order persists:
composite > async-full (3.91) > async-tiled (2.54).
test_bench_registry.py: register matmul-async / -chunked / -chunked-db
(also picks up the earlier milestone-gqa-headline -> milestone-1h-gqa
rename already present in the tree).
--- Remaining work (resume here if interrupted) ---
- Paper §3.4 (03-gemm.tex sec:gemm-vs-async): finish naive->async-full /
chunked->async-tiled rename AND reframe "FIXED_DMA=8 for DMA descriptors"
to single-op(8) vs composite(40). Figure already copied to
docs/report/1H-codesign-paper/figures/gemm_composite_vs_async_tflops.png.
- Paper §3.4 K=3072 para + mechanism #3: update dispatch breakdown to new
model (191 single-op * 8c ~= 1.5us, was 4.6us) and headline gap
~6.3x -> ~2.8x.
- Rebuild build/main.pdf (tectonic) + verify via pdftotext.
- Then commit Group 3 (paper + diagrams + PDF).
- Table 2 / §2 prose / ADR-0064 D8 already done in 2d8271c.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
ADR-0064 D8 broadened from "DMA fast-path" to "single-op-cmd fast-path":
every single-op command (DmaRead/DmaWrite/Gemm/Math/Copy) now pays the
lighter FIXED=8; only CompositeCmd keeps the 40-cycle control-path FIXED
(it alone needs scheduler plan generation + per-tile RW-hazard tracking +
completion wiring). Renamed knob fixed_per_dma_cmd_cycles ->
fixed_per_single_op_cmd_cycles. dispatch_cycles now branches on
"is CompositeCmd" rather than enumerating DMA types.
Term choice: "single-op" (not "atomic", which read as sync/async) — the
axis is composition (one engine op vs fused multi-op plan), orthogonal to
timing. single-op <-> composite.
Tests: test_pe_cost_model.py updated to the single-op surface (defaults,
fast-path over all 5 single-op cmd types, composite general path, yaml
override). All green.
Recalibrated tests/attention/test_gqa_decode_opt2.py
::test_opt3_dispatch_exceeds_opt2 — NOT a regression: D8 makes single-op
cmds 5x cheaper, so opt2's two-composite fusion win over opt3's many
single-ops narrowed from pre-D8 ~3.7x to ~1.87x (opt3=224 > opt2=120).
The CPU-offload invariant (opt2 cheaper) still holds; only the model-
dependent ">2x" constant was over-fit to the old uniform-40 model. Gate
now: direction + >1.5x margin (matches sibling R-sweep test's stated
"absolute ratio informative-only" philosophy).
NOTE for review: ADR-0065's "2x CPU-offload win" headline may want a
refresh to reflect the post-D8 ~1.87x — left to user (architectural doc).
Full regression: 826 passed, 1 skipped (tests/ excl. tests/gemm).
--- Remaining work (resume here if interrupted) ---
5. Re-run scripts/paper/paper_plot_gemm_async_vs_composite.py with new
cost model; verify async-tiled dispatch overhead drops (~4576ns ->
~1536ns expected) and the composite-vs-async-tiled gap narrows from
the prior ~6.3x at K=3072.
6. Copy regenerated gemm_composite_vs_async_tflops.png to
docs/report/1H-codesign-paper/figures/.
7. Paper §3.4 (03-gemm.tex sec:gemm-vs-async): finish naive->async-full /
chunked->async-tiled rename AND reframe FIXED_DMA wording to single-op
vs composite (currently still says "lighter FIXED for DMA descriptors,
FIXED_DMA=8"). Table 2 (02-platform) + §2 dispatch prose already done.
8. Paper §3.4 K=3072 corner para + mechanism #3: update dispatch breakdown
to new model (96 DMA*8 + 95 single-op*8 ≈ 1.5us vs old 4.6us); update
headline ratio if it changed.
9. Rebuild docs/report/1H-codesign-paper/build/main.pdf (tectonic) +
verify via pdftotext.
10. Then this is the bench-harness + paper commits (Groups 2 & 3).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
The five-stage chain was set as a centered display equation, which
overflowed the column and clipped the last 'DMA_WRITE' label. The
inline prose right below it also repeated the same chain in a
shorter form. Consolidate into one inline parenthetical listing the
five stage names, and reuse 'flows through the chain' for the
self-routing description — no clipping, no repetition.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
The matplotlib title and gray subtitle were duplicating what the
figure caption already says in the LaTeX source, and crowding the
top of every chart. Drop both — chart now leaves the title/subtitle
slots blank and the caption is the single source of truth for
chart titling.
Re-render all 5 GEMM figures (mac util measured, mac util theoretical
vs measured, stage breakdown, HBM BW util, per-PE TFLOPS) and resync
into docs/report/1H-codesign-paper/figures/. No data changes.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Two new evaluation plots for §3 GEMM, both using the composite window
as the denominator (the up-front tl.load of A in load_ref is therefore
excluded — only HBM traffic and compute inside the composite count):
- gemm_hbm_bw_util.png: per-PE HBM bandwidth utilization against the
256 GB/s per-PE ceiling. Answers "is this workload memory-bound on
this configuration?" — small/single-tile shapes sit at 22–46%
(pipeline-fill-limited), large or output-write-dominated shapes
saturate (≥85%).
- gemm_per_pe_tflops.png: per-PE GEMM throughput against the 8 TFLOP/s
engine peak. The deep-K K=3072 load_ref case lands at
7.18 TFLOP/s (~90% of peak) — the configuration's clean win.
ref_ref at the same shape drops to 3.83 TFLOP/s because the second
operand doubles HBM pressure and the kernel hits the BW ceiling.
The variant gap on this chart is the operational cost of NOT
pre-staging the activation.
Both charts compare two operand-staging variants on every shape:
load_ref ("activation pre-staged", weight-only HBM streaming) and
ref_ref (both A and W streamed from HBM). load_load is omitted —
with both operands pre-staged the composite carries no HBM traffic
and the BW metric collapses to 0.
Analytic / measured peak unified to the single hardware spec
(8.0 TFLOP/s = 8000 flops/ns). T_STAGE is now derived as
tile_flops / peak (= 16.384 ns for the 32×64×32 tile) rather than
the previous hardcoded 16 ns, so MAC efficiency and per-PE TFLOPS%
share the same denominator and never disagree. Side effect: max
analytic-vs-measured gap tightens from 2.2 ppt to 1.4 ppt across
the sweep.
§3 Results restructured: lead with the two new evaluation plots
(BW saturation, achieved throughput), then the MAC-utilization
analytic-vs-measured chart serves as the validation step, then the
per-stage engine wall-clock as the supporting diagnostic. §3
Analysis updated to use the load_ref / ref_ref contrast as the
hardware-software boundary line that motivates the GQA kernel of §5.
§2.4 Accuracy claim updated to match: GEMM analytic-vs-measured
agreement is now "within 1.4 ppt across every swept shape", from
~7.7% at single-tile up to ~90% at K=3072. Subtitle/title vertical
stacking glitch in the matplotlib charts fixed in passing.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Three coupled fixes that recover small-tile GEMM pipeline efficiency
from 53% to 88% (32x3072x32 load_ref, composite_window basis).
1. PE_DMA channel-hold (ADR-0014 D4 clarified): both the
_handle_with_hooks (PeInternalTxn) and _pipeline_process
(TileToken) paths used to hold the cap=1 DMA channel through the
full HBM round-trip, which double-serialized with the HBM_CTRL's
own per-PC `available_at` model and prevented back-to-back tile
DMAs from amortizing their per-request head latency. Channel is
now released after the request is enqueued onto the next hop;
HBM serialization is HBM_CTRL's responsibility alone.
Tests: new test_pe_dma_back_to_back_pipelining as the oracle
(asserts wall < 75% of strict-serialized N x single_op). Existing
test_pe_dma_record_start_after_channel_acquire rewritten to assert
t_start clustering (channel released fast) instead of the old
round-trip-hold invariant. test_pe_dma_same_channel_serializes
still passes — HBM_CTRL preserves ordering.
Probe regression: PE→local-HBM 32 KiB stays at 141 ns
(single-request, unaffected).
2. milestone_1h_gemm bench: matmul_composite was reading MATMUL_M/K/N
env vars at module load, so every sweep row replayed the cached
256³ result; values now read inside run(). Drops the stale
sys.modules deletion hack.
3. Analytic ideal-pipeline model: dropped the (n_mn-1)·dma_w_per_pair
penalty (over-pessimistic for under-tile shapes — it pushed
measured > theoretical) and replaced the D_STAGES-derived head
with empirical T_PIPELINE_FILL=60 ns / T_PIPELINE_TAIL=30 ns.
Max analytic-vs-measured gap across all 7 swept shapes now 2.2 ppt
(was 9-44 ppt under the old constants).
Paper updates:
- §3 (GEMM): 78%→88% measured at 48 tiles, 23%→15% at 1 tile,
stage breakdown numbers refreshed (DMA in / Fetch / GEMM all
~785 ns at K=3072), analytic-vs-measured agreement tightened
to "within 2.2 ppt".
- §2.4 (Accuracy): GEMM tracking claim refreshed accordingly.
- §5 (GQA): restore long-ctx 4-cases figures into figures/
(they were dropped from bench output dir as derived artifacts in
92b9221 / e45626c but §5 still cites them by name).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
These 8 prefill/decode 4-case PNGs are derived artifacts regenerated
on demand from scripts/paper/paper_plot_gqa_{prefill,decode}_long_ctx_4cases.py
and no longer belong in the committed bench output.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Analytical plot generator + PNG covering the 4 sharding cases from
slide 17 plus the 2 d_head-TP variants (Cases 4, 5). Three panels:
per-PE HBM budget breakdown (Wq + Wk + Wv + Wo + 4.24 GB KV
headroom), per-PE KV memory at S_kv=1M, and per-PE communication
per output token (decode). Numbers match slide 17 (max KV context
~7.1M for the 64-way sharded cases).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Single @bench entry that drives the prefill + decode long-context
4-cases sweeps in one invocation, mirroring milestone-1h-gemm. The
individual gqa_helpers/long_ctx/gqa_{prefill,decode}_long_ctx_4cases
modules are now pure helpers (no @bench), reached only via this
umbrella.
Env var contract:
GQA_1H_RUN=1 (required gate)
GQA_1H_SWEEPS=prefill,decode (default: both; pick subset to skip)
GQA_1H_TOPOLOGY=topology.yaml (override)
Output layout:
benches/1H_milestone_output/gqa/long_ctx/
sweep_prefill.json
sweep_decode.json
gqa_prefill_long_ctx_4cases_{latency,traffic,memory,parallelism}.png
gqa_decode_long_ctx_4cases_{latency,traffic,memory,parallelism}.png
The decode bench config drops S_kv from 131_072 to 8_192 so the umbrella
finishes in minutes — the comparative-story bars are the same shape at
8K. The 131K production headline number is recoverable by overriding
the dispatch; the helper docstring notes this.
Outputs (2 sweep JSONs + 8 PNGs) ship in this commit alongside the
umbrella that produced them, following the milestone-1h-gemm pattern
where derived artifacts live with the bench that emits them.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
mukesh
ywkang
eusonice