Hi Adrián, On 14/02/2024 12:14, Adrián Larumbe wrote: > A driver user expressed interest in being able to access engine usage stats > through fdinfo when debugfs is not built into their kernel. In the current > implementation, this wasn't possible, because it was assumed even for > inflight jobs enabling the cycle counter and timestamp registers would > incur in additional power consumption, so both were kept disabled until > toggled through debugfs. > > A second read of the TRM made me think otherwise, but this is something > that would be best clarified by someone from ARM's side. I'm afraid I can't give a definitive answer. This will probably vary depending on implementation. The command register enables/disables "propagation" of the cycle/timestamp values. This propagation will cost some power (gates are getting toggled) but whether that power is completely in the noise of the GPU as a whole I can't say. The out-of-tree kbase driver only enables the counters for jobs explicitly marked (BASE_JD_REQ_PERMON) or due to an explicit connection from a profiler. I'd be happier moving the debugfs file to sysfs rather than assuming that the power consumption is small enough for all platforms. Ideally we'd have some sort of kernel interface for a profiler to inform the kernel what it is interested in, but I can't immediately see how to make that useful across different drivers. kbase's profiling support is great with our profiling tools, but there's a very strong connection between the two. Steve > Adrián Larumbe (1): > drm/panfrost: Always record job cycle and timestamp information > > drivers/gpu/drm/panfrost/Makefile | 2 -- > drivers/gpu/drm/panfrost/panfrost_debugfs.c | 21 ------------------ > drivers/gpu/drm/panfrost/panfrost_debugfs.h | 14 ------------ > drivers/gpu/drm/panfrost/panfrost_device.h | 1 - > drivers/gpu/drm/panfrost/panfrost_drv.c | 5 ----- > drivers/gpu/drm/panfrost/panfrost_job.c | 24 ++++++++------------- > drivers/gpu/drm/panfrost/panfrost_job.h | 1 - > 7 files changed, 9 insertions(+), 59 deletions(-) > delete mode 100644 drivers/gpu/drm/panfrost/panfrost_debugfs.c > delete mode 100644 drivers/gpu/drm/panfrost/panfrost_debugfs.h > > > base-commit: 6b1f93ea345947c94bf3a7a6e668a2acfd310918
