/**
# Performance monitoring (for the Navier--Stokes solvers)

This logs simple statistics available for the various [Navier--Stokes
solvers](/src/README#navierstokes). */

event perfs (i += 1) {
  static FILE * fp = fopen ("perfs", "w");
  if (i == 0)
    fprintf (fp,
	     "t dt mgp.i mgp.nrelax mgpf.i mgpf.nrelax mgu.i mgu.nrelax "
	     "grid->tn perf.t perf.speed npe\n");
  fprintf (fp, "%g %g %d %d %d %d %d %d %ld %g %g %d\n", 
	   t, dt, mgp.i, mgp.nrelax, mgpf.i, mgpf.nrelax, mgu.i, mgu.nrelax,
	   grid->tn, perf.t, perf.speed, npe());
  fflush (fp);
}

/**
If we have a display (and gnuplot works), a graph of the statistics is
displayed and updated at regular intervals (10 seconds as defined in
[perfs.plot]()). */

event perf_plot (i = 10) {
  if (getenv ("DISPLAY"))
    popen ("gnuplot -e 'set term x11 noraise title perfs' "
	   "$BASILISK/navier-stokes/perfs.plot "
	   "& read dummy; kill $!", "w");
}

/**
The graph looks like this:

![Graph displayed by [perfs.h]()](perfs.png)

## Monitoring a distant run

This can also be useful to monitor what is happening to a simulation
running on a remote system. The [perfs.sh]() script provides a
convenient way to do this.

Imagine you started a simulation including the [perfs.h]() file on the
"mesu" system at UPMC (typically using the queueing system) and that
the simulation is running in the `wave/level-10/` directory on
mesu. You can then get a regularly-updated graph of what is happening
using:

~~~bash
bash $BASILISK/navier-stokes/perfs.sh mesu.dsi.upmc.fr:wave/level-10/perfs
~~~

## See also

* [Continuous profiling monitoring](/src/profiling.h).
*/