plot-nr-running

Create heat map and find imbalances from recorded sched_update_nr_running events with trace-cmd.

This script reads output of trace-cmd report command with sched_update_nr_running events. From this data it plots heat map showing number of active tasks on each core of processor with line graph showing imbalance between the numbers.

Usage

Check support of the sched_update_nr_running event in the installed kernel:

trace-cmd list | grep sched_update_nr_running

Generate trace report with sched_update_nr_running events:

trace-cmd record -e sched:sched_update_nr_running  # append a command to trace or terminate with Ctrl+C
trace-cmd report > trace_report.trace

Create heat map with plot-nr-running.py:

./plot-nr-running.py trace_report.trace

Arguments

The report file can be specified as positional argument, or passed through stdin:

./plot-nr-running.py trace_report.trace
trace-cmd report | ./plot-nr-running.py

Other optional arguments can be viewed using --help arguments:

  --sampling SAMPLING   Sampling of plotted data to reduce drawing point_time
  --threshold THRESHOLD
                        Minimal difference of process count considered as
                        imbalance
  --duration DURATION   Minimal duration of imbalance worth reporting
  --image-file IMAGE_FILE
                        Save plotted heatmap to file instead of showing
  --lscpu-file LSCPU_FILE
                        File with output of lscpu from observed machine

Example

./plot-nr-running.py --lscpu-file example/lscpu.txt --image-file NAS_48_threads_group_imbalance_bug.png NAS_48_threads_group_imbalance_bug.trace.xz