As background, I’ve been trying to trace drm_vblank_event using 3rd party tools for a while. I finally installed Nsight Systems recently hoping it would work this time since there was a direct example in the documentation showing how to trace drm_vblank_event.
Unfortunately, it’s just not working for me. I’m again getting “no events collected…” as I did with third-party tools, even though running sudo cat /sys/kernel/debug/tracing/available_events | grep drm seems to show that it’s traceable. I have already done the changes to enable the drm module in the driver (i.e. setting nvidia_drm modeset=1) and lsmod shows that nvidia, nvidia_drm, nvidia_modeset, and nvidia_uvm are loaded. The only thing that I have not tried is reinstalling Linux completely (since Manjaro did botch a NVIDIA driver install once, leading to me having to do some manual removal/installation to fix that problem)
Is this expected behaviour, or am I missing something?
If it’s the former, I would very much appreciate knowing, as it’s starting to feel like I’m chasing after something that might not even exist in the first place (That is, drm_vblank_event tracing is actually not available with NVIDIA drivers)
EDIT: I seem to have forgotten that I discovered this message a while back while running dmesg | grep drm:
[ 3.956752] [drm] No driver support for vblank timestamp query.
Does this mean that there is indeed no support for tracing drm_vblank_events?