Investigate the use of fpprofiler for toro code about torokernel

[MatiasVara]

We need an script that add some extra code between begin..end; statement.

[MatiasVara]

By compiling the kernel with the "-pg", each function invokes mcount(). So it is possible to count the number of time a function is executed. It may be possible to sample the registers of each core by using the qemu monitor. For example, we could do it every 100ms and then get a graph that shows where toro elapses most of the time.

[MatiasVara]

while true; do
  s=`echo "info cpus" | netcat 127.0.0.1 55555 | gawk '{ match($0, /=([0-9,x,a-f]+)/, arr); if(arr[1] != "") print arr[1] }'`
  k=`addr2line -s -f -e StaticWebServer $s`
  echo $k
  # sleep 0.1
done

[MatiasVara]

I better way is to use the QMP to get:

• $EIP register
• $EBP+8
  Then you can get the current function and the parent's function.
  Add this to qemu-args:
  -qmp unix:./qmp-sock,server,nowait

[MatiasVara]

https://matplotlib.org/gallery/pie_and_polar_charts/pie_features.html#sphx-glr-gallery-pie-and-polar-charts-pie-features-py

[MatiasVara]

./qmp --path=./qmp-sock human-monitor-command --command-line="info registers"

[MatiasVara]

This tool may be developed in a different repo since it is not limited to toro.

[MatiasVara]

The tools is developed in https://github.com/torokernel/qprofiler

[MatiasVara]

By adding -pg, the compilation fails but the mcount() is added. It would be possible to compile the kernel manually linking it.