ac5a55ef11
Viewing CS traces retrieved from the driver is common practice to determine driver bugs but there is no way to determine what function a certain part of the CS was emitted by. This is crucial information to determine what function is responsible for emitting broken CS packets and to help with navigation of the CS trace. Signed-off-by: Mark Collins <mark@igalia.com> Reviewed-by: Danylo Piliaiev <dpiliaiev@igalia.com> Reviewed-by: Yonggang Luo <luoyonggang@gmail.com> Ack-by: Chia-I Wu <olvaffe@gmail.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18271>
65 lines
2.3 KiB
ReStructuredText
65 lines
2.3 KiB
ReStructuredText
u_trace GPU Performance Tracing
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===============================
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Mesa has its own GPU performance tracing framework which drivers may
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choose to implement. ``gpu.renderstages.*`` producer for
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:doc:`Perfetto Tracing <perfetto>` is based on u_trace.
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It doesn't require external dependencies and much simpler to use. Though
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it provides information only about GPU timings and is harder to analyze
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for complex rendering.
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u_trace is useful when one needs to quickly identify performance bottleneck,
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or to build a tool to analyze the raw performance data.
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Drivers which support u_trace:
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- Intel drivers: ANV, Iris
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- Adreno drivers: Freedreno, Turnip
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Usage
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-----
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u_trace is controlled by environment variables:
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:envvar:`MESA_GPU_TRACES`
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controls whether u_trace is enabled and trace output
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``print``
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prints in a human readable text format. It should be noted that this
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is mutually exclusive with ``print_json`` and both cannot be enabled
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at the same time.
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``print_json``
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prints in JSON format, suitable for parsing. Application should
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appropriately finish its rendering in order for trace's json to be
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valid. For the Vulkan API, it is expected to destroy the device,
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for GL it's expected to destroy the context.
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``perfetto``
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enables perfetto instrumentation prior to connecting, perfetto
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traces can be collected without setting this but it may miss some
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events prior to the tracing session being started.
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``markers``
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enables marker instrumentation, will print utrace markers into
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the CS which can then be viewed by dumping the CS from the driver.
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:envvar:`MESA_GPU_TRACEFILE`
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specifies a file where to write the output instead of ``stdout``
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:envvar:`*_GPU_TRACEPOINT`
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tracepoints can be enabled or disabled using driver specific environment
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variable. Most tracepoints are enabled by default. For instance
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``TU_GPU_TRACEPOINT=-blit,+render_pass`` will disable the
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``blit`` tracepoints and enable the ``render_pass`` tracepoints.
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.. list-table::
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:header-rows: 1
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* - Driver
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- Environment Variable
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- Tracepoint Definitions
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* - Freedreno
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- :envvar:`FD_GPU_TRACEPOINT`
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- ``src/gallium/drivers/freedreno/freedreno_tracepoints.py``
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* - Turnip
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- :envvar:`TU_GPU_TRACEPOINT`
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- ``src/freedreno/vulkan/tu_tracepoints.py``
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