Gst Tracing - Strange Results for Latency

[Andreas Wittmann]

Hi,
I tried to use the tracing infrastructure of GStreamer to determine the latency of pipeline elements. After some tests with unexpected results I stripped down my pipeline and set the following env. variables:
set GST_DEBUG=GST_TRACER:7 
set GST_TRACERS=latency(flags=element) 
gst-launch-1.0 videotestsrc num-buffers=1024 ! video/x-raw, width=(int)1920, height=(int)1080, framerate=(fraction)60/1 !  glupload ! fakesink >> out_fhd.txt 2>&1

gst-launch-1.0 videotestsrc num-buffers=1024 ! video/x-raw, width=(int)3840, height=(int)2160, framerate=(fraction)60/1 !  glupload ! fakesink >> out_4k.txt 2>&1

GST_TRACER:The latencies I observed for the glupload element at 1920x1980 were around 1.7ms and for 3840x2160 around 1.9ms. 
PAD PROBE:I wrote a small c program implementing the same Pipeline installing a padprobe at the sink/src pad of the glupload element to start/stop a timer there. In this case I measured an average of 0.8ms for 1920x1080 and 2.2ms for 3840x2160.
After reading the documentation, I´d have expected similar results.
Tracing

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Tracing


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Can you explain the difference? Is it a config problem? The tracing results do not make any sense to me.
My System: Win10, GStreamer 1.16
Thanks!

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