Performance and time
====================

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XGC outputs timing_#########.* files where ######### is the time step, which are used to analyze the performance.
The output frequency is controlled by the input parameters ``mon_flush_count`` and ``mon_flush_freq``.

The current time step (from which the simulation will be restarted) and the number of restarts are written in timestep.dat.

The files timing_#########.txt_stats contain information on the time spent in different sections during execution of the time step.
The sections are set by timers in the code:

**Fortran**

.. code-block:: fortran

   use perf_monitor
   
   call t_startf("REGION_1") !start timer
   ! execute region 1
   call t_stopf("REGION_1") !stop timer

**C++**

.. code-block:: c++

   #include "gptl.h"

   int ierr; //error code
   
   ierr = GPTLstart("REGION_2"); //start timer
   // execute region 2
   ierr = GPTLstop("REGION_2"); //stop timer

There is also a TIMER macro that can be used to time a single function:

.. code-block:: c++

   #include "timer_macro.hpp"

   TIMER("MY_FUNCTION", my_func() );

When developing code it is useful to add your own timers to check the performance.
   
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