Computation between last MPI call and Walltime region end ignored

[ptaffet]

SCOREP_USER_REGION_BY_NAME_BEGIN( "TRACER_WallTime_Test" , SCOREP_USER_REGION_TYPE_COMMON);
usleep(10);
SCOREP_USER_REGION_BY_NAME_END("TRACER_WallTime_Test");

I expect that it TraceR would output:

[ 0 0 : Begin TRACER_WallTime_Test x ]
[ 0 0 : End TRACER_WallTime_Test x+.00001 ]

Where x is some time (in seconds), so .00001 is 10us. Of course, due to context switching, etc. it may not be exactly 10us.

What I’m seeing instead is that there is no difference in the time printed for Begin and End. They are printed to the 1us place, so 10us should be noticeable.

When I look at the trace with otf2-print, I see:

 ENTER                                      0         y                        Region: "TRACER_WallTime_Test" <83>
 LEAVE                                      0          y+139,000        Region: "TRACER_WallTime_Test" <83>

           

I think otf2-print uses nanoseconds, so that’s 139 us. Not exactly 10us, but not 0us either.