Profile a model

Goal

Get one valid result bundle from a board and know what every line of the terminal panel means. You will learn the shape of a run, the difference between the two cycle totals it prints, and where the arena and binary numbers come from.

Hardware and wiring

An Apollo510 EVB connected to the host over its J-Link USB port. Nothing else: the default transport is RTT over the debug connection, so no serial cable and no power instrument. Validate your setup confirms the probe sees the board.

Software prerequisites

hpx (pip install helia-profiler) and a clone of the repository for the quickstart config and model, the GNU Arm toolchain, CMake and Ninja on PATH, SEGGER J-Link software, and on Linux the udev rule (Install). hpx doctor must report the toolchain and J-Link as found.

Config file

examples/quickstart/hpx_rt.yml:

model:
  path: kws_model.tflite
  arena_size: 131072
engine:
  type: helia-rt
  config:
    variant: release-with-logs
target:
  board: apollo510_evb
  toolchain: arm-none-eabi-gcc
profiling:
  pmu_counters:
    cpu: default
    memory: default
  per_layer: true
  iterations: 3
  warmup: 1
power:
  enabled: false
output:
  format: csv
  dir: ./results/results_rt

The model path is relative to the config file, so run from examples/quickstart/ or pass the model on the command line. Every key is on the generated configuration reference.

Run

cd examples/quickstart
hpx profile --config hpx_rt.yml

Or without a file, from anywhere:

hpx profile examples/quickstart/kws_model.tflite --board apollo510_evb --engine helia-rt

The first run resolves and builds the NSX dependency workspace, which takes minutes; later runs reuse it.

Expected output

The results panel of the nightly case named under Validated on (the Memory and Plan vs measured tables that follow it are on Memory placement; the arena progress bar and the host wall-clock subtitle are omitted):

─────────────────────────────────── Results ────────────────────────────────────
  Engine              helia-rt
  Compatibility       qualified
  Board               apollo510_evb
  Layers              13
  Total cycles        2,060,239
  Clean E2E cycles    2,051,232  (-0.4% vs per-layer sum)
  Total MACs          2,656,768
  Total OPS           5,321,596
  Cycles/MAC          0.78
  Parameters          22,604
Top Layers by Cycles
   #   Operator                     Cycles         %           MACs    Cyc/MAC
   1   CONV_2D                     337,348     16.4%        320,000        1.1
   2   DEPTHWISE_CONV_2D           216,207     10.5%         72,000        3.0
   3   DEPTHWISE_CONV_2D           216,205     10.5%         72,000        3.0
   4   DEPTHWISE_CONV_2D           216,194     10.5%         72,000        3.0
   5   DEPTHWISE_CONV_2D           216,192     10.5%         72,000        3.0
  Arena      29,780 / 32,768 bytes  91%
  Model      53,744 bytes
  Binary Sections
  Section        Size
  text        278,596
  data        154,796
  bss          86,260
  reserved    365,404
  total       885,056
  Validity: VALID
╭─ Output → results/… ───────────╮
│    profile_results.csv         │
│    summary.json                │
│    run_metadata.json           │
│    nsx.lock                    │
│    result_manifest.json        │
╰────────────────────────────────╯

How to read it

• Clean E2E cycles is the inference cost: the firmware ran the model warm, back to back, with no per-layer instrumentation, and averaged 46 inferences. Total cycles is the sum of the instrumented per-layer rows and is 0.4% higher because every operator was bracketed by a counter read. Publish the clean number (Latency and per-layer).
• Top Layers by Cycles ranks the per-layer rows; Cyc/MAC divides by the operator’s multiply-accumulates from the host-side model analysis. A depthwise convolution at 3.0 cycles per MAC next to a full convolution at 1.1 is the usual shape: depthwise has less arithmetic per byte moved.
• Arena 29,780 / 32,768 is the interpreter’s allocation against the configured arena_size; a run that reports the arena does not fit stops before flashing. The quickstart config asks for 131,072 bytes, which is what this model needs with headroom; the nightly case used 32,768.
• Validity: VALID and an empty issue list mean the run is a measurement. A DEGRADED or INVALID verdict lists codes to look up on the issue codes page.
• The five files are described on Output files; summary.json has every number above in machine-readable form.

Variations

• Other boards, same config with --board: the same nightly run profiled this model on apollo330mP_evb (2,056,992 clean cycles, Cortex-M55), apollo3p_evb (10,186,141, Cortex-M4, DWT cycle counter only) and apollo4l_blue_evb (8,683,558, Cortex-M4); those bundles ship beside the Apollo510 one. Cortex-M4 boards capture cycles only, not the PMU groups (Boards and targets).
• More iterations: --iterations 20 --warmup 5 tightens the per-layer median; the clean window is sized separately by window_target_ms.
• Another engine or toolchain: Compare engines, Compare toolchains.
• A JSON bundle: --output-format json writes profile_results.json instead of the CSV.

Validated on

Board	apollo510_evb (Apollo510, Cortex-M55, lp clock tier, 96 MHz as recorded in the bundle’s run_metadata.json)
Run	nightly hardware validation run 35078330526, 2026-09-16 09:15 UTC, suite complete, hpx 0.1.6 at source commit 0714893
Case	apollo510_evb-kws-rt-ns-arm-none-eabi-gcc-rtt-auto, verdict valid, no issues
Model	kws_model.tflite, SHA-256 935c513a…bdf038, the same bytes as the quickstart file
nsx modules	baseline hpx-neuralspotx-0.8.1-2026-09: nsx-helia-rt helia-rt-v1.20.0 (edb3a25), nsx-cmsis-nn aaeb145, nsx-ambiq-sdk a9f4ec2, nsx-pmu-armv8m 5725c06, nsx-board-apollo510-evb packaged with neuralspotx 0.8.1
Toolchain	arm-none-eabi-gcc 15.2.1 (Arm GNU Toolchain 15.2.Rel1), CMake 4.1.2
Differences from the config above	the nightly case used arena_size: 32768, pmu_counters: {cpu: default} and output.format: csv; the quickstart config adds the memory group and a larger arena
Bundle	examples/results/hardware-validation-2026-09-16/apollo510_evb-kws-rt-ns-arm-none-eabi-gcc-rtt-auto/