quasar-perf-test

name	quasar-perf-test
description	Create, extend, debug, and validate Quasar LLK performance tests and their PerfRunType kernel paths. Use when adding perf_[op]_quasar.py, wiring PerfConfig, implementing UNPACK_ISOLATE / MATH_ISOLATE / PACK_ISOLATE / L1_CONGESTION, or investigating implausible Quasar perf metrics and dvalid handshakes.

Quasar Perf Test

Goal

Create or repair a Quasar performance test while preserving its functional L1_TO_L1 behavior. Reuse the correctness harness, report through PerfConfig, and give every applicable PerfRunType a balanced single-stage or congestion path.

This skill covers two related workflows:

• Create: add a perf harness for an existing correctness test.
• Repair or extend: implement or debug run-type behavior in an existing Quasar kernel.

Choose the workflow

1. If tests/python_tests/quasar/perf_[op]_quasar.py does not exist, follow Create a perf test.
2. If the perf harness exists but run types are missing, hanging, or producing implausible metrics, follow Repair PerfRunType paths.
3. In either case, finish with Validation.

Create a perf test

1. Read:

   • tests/python_tests/quasar/test_[op]_quasar.py
   • tests/sources/quasar/[op]_quasar_test.cpp
   • the closest current Quasar perf test with the same pipeline shape

2. Move reusable parameter axes from inline lambdas into named helpers when the perf harness needs them.

3. Add tests/python_tests/quasar/perf_[op]_quasar.py.

4. Mark it with @pytest.mark.perf and @pytest.mark.quasar.

5. Import the correctness test as a helper, normally:

   from test_[op]_quasar import test_[op]_quasar as run_[op]_quasar
   

6. Use a narrow perf-oriented sweep:

   • run_types=PERF_RUN_TYPES_QUASAR from helpers.llk_params
   • a fixed loop_factor=32, unless the operation has an established value
   • a fixed is_perf=True
   • stable dimensions and exact destination fill when normalization depends on shape

7. Pass perf_report and is_perf=True to the correctness helper.

8. Add keyword-only is_perf=False and perf_report=None to that helper. Build shared test_config_kwargs, then:

   if is_perf:
       if perf_report is None:
           raise ValueError("perf_report must be provided when is_perf=True")
       PerfConfig(run_types=run_types, **test_config_kwargs).run(perf_report)
       return
   

9. Keep the correctness path on TestConfig with an explicit PERF_RUN_TYPE(PerfRunType.L1_TO_L1).

10. Preserve dynamic shape coverage in correctness tests. Use fixed, comparable workloads only for the perf path.

C++ structure

In tests/sources/quasar/[op]_quasar_test.cpp:

• Include perf.h and profiler.h.
• Put setup in ZONE_SCOPED("INIT").
• Put repeated work in ZONE_SCOPED("TILE_LOOP").
• Read LOOP_FACTOR and use it in steady-state work.
• Branch with compile-time if constexpr (PERF_RUN_TYPE == ...).
• End each profiled zone with PROFILER_SYNC().
• Preserve the functional L1_TO_L1 path.
• Use current Quasar LLK signatures and TensorShape APIs; do not copy stale call signatures from older perf branches.

Use the target Quasar correctness kernel for current Quasar LLK signatures. The generic perf references use older-architecture APIs and must not be copied verbatim.

Do not copy loop counts blindly. Derive them from the target kernel's actual MOP and handshake behavior.

Required run-type behavior

Implement behavior independently in unpack, math, and pack:

Run type	Unpack	Math	Pack
L1_TO_L1	Real	Real	Real
UNPACK_ISOLATE	Real	Clear exactly the source dvalids unpack produces	No-op
MATH_ISOLATE	Produce exactly the source dvalids math consumes	Real; do not signal inactive pack	No-op
PACK_ISOLATE	No-op	No-op	Real without waiting for math
L1_CONGESTION	Real	Clear source dvalids only	Real independently

Adapt this table to the real pipeline. For example, an unpack-to-dest kernel may bypass math entirely.

Repair PerfRunType paths

1. Read the C++ kernel, correctness harness, perf harness, and latest perf_data/<test>/<test>.post.csv.
2. Map every producer/consumer handshake:
   • SrcA and SrcB dvalid between unpack and math
   • destination dvalid between unpack/math and pack
   • semaphore-based unpack-to-dest synchronization
3. Inspect the LLK MOP when pulse counts are not explicit.
4. Determine the exact pulse count for one kernel invocation.
5. Implement or correct each run-type branch.
6. Compile a focused sweep.
7. Run all run types together to expose sticky state.
8. Inspect TILE_LOOP metrics and run the functional test.
9. Restore the intended full sweep after focused debugging.

Source dvalid accounting

The mock count must match hardware behavior exactly:

total source handshakes =
    LOOP_FACTOR
  × real operation invocations per loop
  × dvalid pulses per invocation

• Use _perf_unpack_loop_set_valid<set_a, set_b>(count) only when unpack is mocked for MATH_ISOLATE.
• Use _perf_math_loop_clear_valid<clear_a, clear_b>(count) only when math mocks consumption for UNPACK_ISOLATE or L1_CONGESTION.
• Count tiles and blocks actually consumed.
• Determine whether the MOP pulses per tile or per face.
• Determine whether math consumes SrcA, SrcB, or both.

Known cases:

• Scalar binary broadcast clears SrcAB once on the final outer-loop iteration: one handshake per tile, not per face.
• Row/column broadcast may handshake per face; inspect the MOP.
• Quasar 32-bit unary datacopy uses ELWADD. Unpack produces real SrcA and dummy SrcB, so both mock sides use <true, true>.
• A block kernel commonly needs LOOP_FACTOR * BLOCK_RT_DIM * BLOCK_CT_DIM.

Never add a synthetic SET/CLEAR pair to flush the pipeline. An extra token can race the final operation and pollute a later run.

Destination dvalid rules

Only signal completion when the consumer is active:

• L1_TO_L1: retain real producer-to-pack setup and section-done calls.
• MATH_ISOLATE: run math without _llk_math_set_dvalid_.
• PACK_ISOLATE: pack without waiting for math and without destination section-done.
• L1_CONGESTION: unpack and pack run independently; math does not pulse destination dvalid.
• UNPACK_ISOLATE: do not signal inactive pack.

Quasar CFG state can persist between run types. For independent pack execution, clear the wait mask during INIT when required:

auto cfg = (volatile std::uint32_t*)TENSIX_CFG_BASE;
cfg[PACK_DEST_DVALID_CTRL_wait_mask_ADDR32] = 0;

Configure set_up_dest_dvalid_per_thread only when the matching producer and consumer are active.

Unpack-to-dest

• A missing math-isolate metric is expected when math is compiled out.
• L1_TO_L1 performs real unpack and signals active pack.
• UNPACK_ISOLATE performs real unpack without signaling inactive pack.
• L1_CONGESTION runs unpack and pack independently.
• MATH_ISOLATE must not emit dummy source dvalid without a math consumer.

Diagnose metrics

Analyze marker == TILE_LOOP first.

Healthy relationships:

• L1_CONGESTION[UNPACK] is close to UNPACK_ISOLATE.
• L1_CONGESTION[PACK] is close to PACK_ISOLATE.
• Format and destination-mode changes have bounded, explainable effects.

Failure signals:

• Values near large powers of two such as 2048, 4096, or 8192
• Healthy first variant followed by very slow variants
• Isolate cost orders of magnitude above the corresponding real stage
• Congestion cost orders of magnitude above isolate
• A passing run that leaves the next run slow

Treat these as likely handshake, mock-count, section-done, or wait-mask bugs; pytest completion alone does not validate the metrics.

Validation

From the tt-llk root:

1. Use the repository LLK test runner workflow, not direct pytest.
2. Compile a focused perf variant, then run all run types together.
3. Confirm each focused pytest case passes.
4. Inspect every focused TILE_LOOP CSV row.
5. Run the shared non-perf correctness test, including unpack-to-dest and destination-accumulation variants when applicable.
6. Check edited files for lint errors and run git diff --check.

Do not:

• weaken functional assertions;
• change LLK library code before isolating a test-kernel orchestration bug;
• leave the permanent sweep narrowed accidentally;
• declare success from pytest alone when metrics are implausible.