AMDGPU DC Gets "PERF_TRACE" To Help With Performance Profiling

Written by Michael Larabel in Radeon on 11 October 2018 at 08:53 AM EDT. 3 Comments
RADEON
Published on Wednesday was the latest batch of AMDGPU DC display code changes for its eventual inclusion into the AMDGPU DRM driver for mainline past the 4.20~5.0 cycle with that feature merge window being over. The most notable change with this latest AMDGPU DC haul is a new "PERF_TRACE" addition.

The 26 patches sent out on Wednesday refactor the DCE clock code as well as the DC to SMU interface. Most interesting to us though is this PERF_TRACE feature on Linux. This PERF_TRACE functionality isn't to be confused with the perf subsystem nor the perf-trace user-space utility.

This AMDGPU DC PERF_TRACE feature is for exposing performance data from the AMDGPU driver for helping its developers make performance improvements.

PERF_TRACE is basically a debug call to place before and after the AMDGPU specific code being tested. Calls to AMDGPU's PERF_TRACE will then post the time (in nanoseconds) to a new amdgpu_perf_trace debugfs file as well as the number of GPU reads/writes that happened in that span. It's a basic approach for allowing the driver developers to help understand their driver performance in a basic level but this feature isn't of any relevance to end-users.

Those wishing to test out the latest AMDGPU DC code in general for ensuring no display regressions can find the patches for now on the amd-gfx list.
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