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69 lines
1.8 KiB
ReStructuredText
69 lines
1.8 KiB
ReStructuredText
Metal Debugger
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==============
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.. currentmodule:: mlx.core
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Profiling is a key step for performance optimization. You can build MLX with
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the ``MLX_METAL_DEBUG`` option to improve the Metal debugging and
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optimization workflow. The ``MLX_METAL_DEBUG`` debug option:
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* Records source during Metal compilation, for later inspection while
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debugging.
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* Labels Metal objects such as command queues, improving capture readability.
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To build with debugging enabled in Python prepend
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``CMAKE_ARGS="-DMLX_METAL_DEBUG=ON"`` to the build call.
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The :func:`metal.start_capture` function initiates a capture of all MLX GPU
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work.
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.. note::
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To capture a GPU trace you must run the application with
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``MTL_CAPTURE_ENABLED=1``.
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.. code-block:: python
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import mlx.core as mx
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a = mx.random.uniform(shape=(512, 512))
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b = mx.random.uniform(shape=(512, 512))
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mx.eval(a, b)
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trace_file = "mlx_trace.gputrace"
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# Make sure to run with MTL_CAPTURE_ENABLED=1 and
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# that the path trace_file does not already exist.
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mx.metal.start_capture(trace_file)
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for _ in range(10):
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mx.eval(mx.add(a, b))
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mx.metal.stop_capture()
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You can open and replay the GPU trace in Xcode. The ``Dependencies`` view
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has a great overview of all operations. Checkout the `Metal debugger
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documentation`_ for more information.
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.. image:: ../_static/metal_debugger/capture.png
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:class: dark-light
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Xcode Workflow
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--------------
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You can skip saving to a path by running within Xcode. First, generate an
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Xcode project using CMake.
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.. code-block::
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mkdir build && cd build
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cmake .. -DMLX_METAL_DEBUG=ON -G Xcode
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open mlx.xcodeproj
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Select the ``metal_capture`` example schema and run.
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.. image:: ../_static/metal_debugger/schema.png
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:class: dark-light
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.. _`Metal debugger documentation`: https://developer.apple.com/documentation/xcode/metal-debugger
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