4308668a25
When debugging a game that compiles a ton of shaders at beginning, it can be very very slow because shaders cache was disabled by default with RADV_DEBUG=hang. To make debugging such a game faster, let's cache shaders with RADV_DEBUG=hang. Note that only the backend IR (ACO or LLVM) and the disassembly are stored in the cache. To get SPIR-V and NIR, you might need RADV_DEBUG=hang,nocache. This also handles the trap handler. Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32246>
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85 lines
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.. _radv-debug-hang:
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Debugging GPU hangs with RADV
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=============================
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UMR (optional)
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--------------
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UMR is needed for dumping a lot of useful information. Clone, build and install
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`UMR <https://gitlab.freedesktop.org/tomstdenis/umr>`__. Do not forget to run
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``chmod +s $(which umr)`` so RADV can actually access UMR.
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UMR needs to access some kernel debug interfaces:
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.. code-block:: sh
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chmod 777 /sys/kernel/debug
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chmod -R 777 /sys/kernel/debug/dri
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Secure boot has to be disabled as well.
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Generating and analyzing hang reports
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-------------------------------------
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With UMR installed, you can now set ``RADV_DEBUG=hang`` which makes RADV insert
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trace markers and synchronization and check for hangs. The hang report will be
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saved to ``~/radv_dumps_<pid>_<time>``. Inside the directory of the hang report,
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there are a couple of files:
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* ``*.spv``: SPIR-V binaries of the pipeline that was bound when the hang
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occurred.
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* ``app_info.log``: ``VkApplicationInfo`` fields.
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* ``bo_history.log``: A list of every GPU memory allocation and deallocation.
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If the GPU hang was caused by a page fault, you can use
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`radv_check_va.py <https://gitlab.freedesktop.org/mesa/mesa/-/blob/main/src/amd/vulkan/radv_check_va.py>`__
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to figure out if address is invalid or used after the memory was deallocated.
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* ``bo_ranges.log``: Address ranges that were valid at the time of submission.
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* ``dmesg.log``: Output of ``dmesg``, if available.
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* ``gpu_info.log``: Fields of ``radeon_info``.
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* ``pipeline.log``: IR of the shaders that were bound during the hang as well as
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programm counters of waves executing said shaders and bound descriptors.
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* ``registers.log``: Various GPU state registers.
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* ``trace.log``: An annotated list of the command stream that caused the hang.
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the commands that hung come after
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``!!!!! This is the last trace point that was reached by the CP !!!!!``.
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* ``umr_ring.log``: Similar to ``trace.log``.
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* ``umr_waves.log``: A list of waves that were active at the time of the hang,
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including register values.
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* ``vm_fault.log``: The page fault address if a page fault occurred.
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Note: By default, the backend IR (ACO or LLVM) and the disassembly should be
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dumped to ``pipeline.log``. But due to shaders caching, you might need
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``RADV_DEBUG=hang,nocache`` to get SPIR-V and NIR in the GPU hang report.
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Debugging Steam games
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---------------------
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Steam games require a bit more work so RADV can access UMR: In your Steam library,
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make sure **Tools** is checked and search for **Steam Linux Runtime**.
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Under **Properties** -> **Installed Files**, click **Browse**, open
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``_v2-entry-point`` and add
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.. code-block:: sh
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shift 2
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exec "$@"
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at the top of the file. Hang debugging can be enabled by selecting the faulting
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game and adding ``RADV_DEBUG=hang %command%`` under **Properties** -> **General**
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-> **LAUNCH OPTIONS**.
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Debugging hangs without RADV_DEBUG=hang
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---------------------------------------
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In some situations, ``RADV_DEBUG=hang`` wouldn't be able to generate a GPU hang
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report, like for synchronization issues (because it enables
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``RADV_DEBUG=syncshaders`` behind the scene). An alternative solution is to
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disable GPU recovery by adding ``amdgpu.gpu_recovery=0`` to your kernel command
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line options. And then invoke UMR manually with
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``umr --by-pci <pci_id> -O bits,halt_waves -go 0 -wa <ring> -go 1 2>&1`` for
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dumping the waves and ``umr --by-pci <pci_id> -RS <ring> 2>&1`` for dumping the
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rings once the GPU hang occurred.
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