Add minimal documentation for PAPI counters

doc/doxygen/chapters/380_offline_performance_tools.doxy

@@ -2,7 +2,7 @@
  *
  * Copyright (C) 2011,2012,2015-2017                      Inria
  * Copyright (C) 2010-2019                                CNRS
- * Copyright (C) 2009-2011,2014-2017,2019                 Université de Bordeaux
+ * Copyright (C) 2009-2011,2014-2017,2019-2020            Université de Bordeaux
  *
  * StarPU is free software; you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License as published by
@@ -562,6 +562,17 @@ more efficient):
 $ starpu_paje_sort paje.trace
 \endverbatim
 
+\section PapiCounters PAPI counters
+
+Performance counter values can be obtained from the PAPI framework if
+<c>./configure</c> detected the libpapi. One has to set the \ref STARPU_PROFILING
+environment variable to 1 and then specify which counters to record with the
+\ref STARPU_PROF_PAPI_EVENTS environment variable. For instance:
+
+\verbatim
+export STARPU_PROFILING=1 STARPU_PROF_PAPI_EVENTS="PAPI_TOT_INS PAPI_TOT_CYC"
+\endverbatim
+
 \section TheoreticalLowerBoundOnExecutionTime Theoretical Lower Bound On Execution Time
 
 StarPU can record a trace of what tasks are needed to complete the

doc/doxygen/chapters/501_environment_variables.doxy

@@ -2,7 +2,7 @@
  *
  * Copyright (C) 2011-2013,2015-2017                      Inria
  * Copyright (C) 2010-2019                                CNRS
- * Copyright (C) 2009-2011,2013-2019                      Université de Bordeaux
+ * Copyright (C) 2009-2011,2013-2020                      Université de Bordeaux
  * Copyright (C) 2016                                     Uppsala University
  *
  * StarPU is free software; you can redistribute it and/or modify
@@ -535,6 +535,13 @@ Define the idle power of the machine (\ref Energy-basedScheduling).
 Enable on-line performance monitoring (\ref EnablingOn-linePerformanceMonitoring).
 </dd>
 
+<dt>STARPU_PROF_PAPI_EVENTS</dt>
+<dd>
+\anchor STARPU_PROF_PAPI_EVENTS
+\addindex __env__STARPU_PROF_PAPI_EVENTS
+Specify which PAPI events should be recorded in the trace (\ref PapiCounters).
+</dd>
+
 </dl>
 
 \section Extensions Extensions