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FPGA-Neural/hardware/v2/logs/benchmark.log
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micheleandClaude Sonnet 5 77baa8fc16 feat(v2): M7 Dataflow Core - full M1-M6 integration, wake-up loop closed end-to-end
dataflow_core.v integrates dependency_manager (M6) -> neural_director
(M5) -> N_SLOTS x (memory_manager (M4) + neural_processor (M1)) for
the first time. A slot's completion (via neural_director's new
slot_node_id tracking, an additive port) feeds back as a
producer_done event to dependency_manager, waking up any node that
depended on it - closing the dataflow loop without external glue.

Verified end-to-end (Verilator) on a 3-node DAG: two independent
nodes plus a third depending on both, confirmed to dispatch only
after both genuinely complete via real neural_processor computation.
4/4 PASS.

Real synthesis + nextpnr-ecp5 P&R via a synthesis-only timing harness
(bare per-slot backend ports exceed the LFE5U-45F's TRELLIS_IO
budget, same pattern as ERR-0005): N_SLOTS=2 -> 165.15 MHz,
N_SLOTS=4 -> 133.19 MHz, both PASS at 80MHz, 0 synthesis problems.

Scope explicitly deferred to M8 (DEC-0009): M3's BRAM buffers not
wired in yet, per-slot Memory Backend Interface ports not arbitrated
to one shared PSRAM master yet - both need real measured data before
committing to a design, not guessed at here.

Logged: simulation/synthesis/timing/benchmark/decisions (DEC-0009)/
experiments (EXP-0008)/errors (ERR-0007, a Yosys chparam-ordering
build quirk, not an RTL bug)/development.log, ROADMAP.md updated.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
2026-09-05 15:05:28 +02:00

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# V2 benchmark log -- solo append, mai troncato/sovrascritto (vedi README.md)
# Nessuna entry ancora -- popolato incrementalmente man mano che avanza lo sviluppo V2.
[2026-09-05] M1 single Neural Processor, isolated (no array/director/
memory manager yet -- system-level numbers deferred to M9)
| Config | Fmax (POST-P&R) | LUT | FF | DSP | BRAM |
|----------------------|------------------|-----|-----|-----|------|
| P_IN=8, ACC_WIDTH=32 | 183.12 MHz | 55 | 533 | 8 | 0 |
| P_IN=8, ACC_WIDTH=24 | 176.21 MHz | 49 | 509 | 8 | 0 |
Reference (V1, hardware/v1/synthesis/p8/, isolated neuron_parallel,
PARALLEL=8, N_INPUTS=256): 61.71 MHz POST-P&R.
All Fmax figures above are POST-P&R (real nextpnr-ecp5), not
theoretical or simulated-only. MAC/cycle, cycles/neuron, neurons/s,
stall %, effective MAC/s: not yet meaningful at this milestone (single
isolated processor, no streaming benchmark harness yet -- deferred to
M2 once neural_processor_array.v exists and a real workload can be
timed end-to-end).
[2026-09-05] M2 Neural Processor Array, N_PROCESSORS sweep (P_IN=8,
ACC_WIDTH=32 each; synthesized via the timing harness, see errors.log
ERR-0005 for why)
| N_PROCESSORS | Fmax (POST-P&R) | LUT | FF | DSP (MULT18X18D) | DSP % of 72 |
|--------------|------------------|-----|------|-------------------|-------------|
| 1 | 159.11 MHz | 59 | 409 | 8 | 11% |
| 2 | 149.59 MHz | 106 | 786 | 16 | 22% |
| 4 | 151.01 MHz | 207 | 1540 | 32 | 44% |
| 8 | 134.70 MHz | 374 | 3048 | 64 | 88% |
All figures POST-P&R (real nextpnr-ecp5), all PASS at the 80MHz
target. LUT4 utilization stays under 6% of the device even at N=8;
DSP is the binding resource (see decisions.log DEC-0005), reaching 88%
at N=8 -- N_PROCESSORS=9 would already exceed the LFE5U-45F's 72
MULT18X18D budget at P_IN=8. Theoretical MAC/cycle (THEORETICAL, not
yet measured end-to-end -- no real workload/benchmark harness exists
until M9): N_PROCESSORS * P_IN MACs/cycle when all processors are
simultaneously streaming tiles (8, 16, 32, 64 for N=1/2/4/8 -- verified
achievable in principle by EXP-0003's concurrent/staggered simulation,
not yet measured as a sustained throughput number).
[2026-09-05] M3 buffers -- BRAM cost vs DEPTH (real Yosys synth_ecp5)
| Module | DEPTH | DP16KD | LUT4 | FF |
|--------------------|-------|--------|------|-----|
| activation_buffer | 4096 | 2 | 37 | 30 |
| activation_buffer | 256 | 1 | 21 | 26 |
| weight_buffer | 512 | 2 | 88 | 139 |
| weight_buffer | 64 | 2 | 73 | 136 |
| result_buffer | 4096 | 2 | 37 | 30 |
| result_buffer | 256 | 1 | 21 | 26 |
weight_buffer's DP16KD count is flat across an 8x depth reduction --
its 64-bit TILE_WIDTH (P_IN=8 * DATA_WIDTH=8), not DEPTH, determines
BRAM count for this module. activation_buffer/result_buffer (byte-
wide) scale as expected with depth. Confirms §14's warning literally:
"non assumere che buffer piu' grandi siano automaticamente migliori"
-- here, smaller was not cheaper either, because depth was the wrong
lever for this specific buffer's cost.
[2026-09-05] M4 Memory Manager + Prefetch Engine (standalone resource
count; Fmax via timing harness -- see errors.log ERR-0005)
| Module | Fmax (POST-P&R) | LUT | FF | DSP | CCU2C |
|----------------------------------|------------------|-----|-----|-----|-------|
| memory_manager + prefetch_engine | 165.86 MHz | 851 | 789 | 0 | 108 |
End-to-end (real PSRAM + real neural_processor, SIMULATED only, no
system-level P&R yet -- deferred to M7/M9): 3-tile job = 446 cycles,
1-tile job = 166 cycles, 5-tile job = 728 cycles. ~140-150 cycles/tile,
dominated by psram_model.v's real ~70ns TAA access latency, not by
memory_manager's own control overhead (its bank-swap turnaround is
documented as a fixed +1 cycle/tile in decisions.log DEC-0006, a small
fraction of the ~140-cycle PSRAM-dominated total).
[2026-09-05] M5 Neural Director (standalone resource count; Fmax via
timing harness -- see errors.log ERR-0005)
| Module | Fmax (POST-P&R) | LUT | FF | DSP | CCU2C |
|------------------|------------------|-----|-----|-----|-------|
| neural_director (N_SLOTS=4) | 250.50 MHz | 382 | 366 | 0 | 4 |
[2026-09-05] M6 Dependency Manager (real standalone synthesis + P&R,
no harness needed)
| Module | Fmax (POST-P&R) | LUT | FF | DSP | CCU2C |
|----------------------|------------------|-----|-----|-----|-------|
| dependency_manager (N_NODES=16) | 155.30 MHz | 763 | 474 | 0 | 0 |
[2026-09-05] M7 Dataflow Core (full M1-M6 integration; resources via
real standalone synthesis, Fmax via timing harness -- see errors.log
ERR-0005)
| Module (config) | Fmax (POST-P&R) | LUT4 | CCU2C | FF | DSP | BRAM |
|-------------------------------|------------------|------|-------|------|-----|------|
| dataflow_core (N_SLOTS=2) | 165.15 MHz | 2127 | 248 | 2505 | 16 | 0 |
| dataflow_core (N_SLOTS=4) | 133.19 MHz | 3953 | 500 | 4688 | 32 | 0 |
DSP budget on the LFE5U-45F is 72 MULT18X18D total: N_SLOTS=4 already
uses 32/72 (44%), consistent with DEC-0005's finding that DSP, not
LUT/FF, is the first resource to saturate as concurrency grows (M2's
own N_PROCESSORS=8 measurement: 88%). BRAM=0 on both is expected --
M3's buffers are not wired into dataflow_core yet (DEC-0009).