- ``-gdb`` is equivalent to ``-wrapper "gdb --args" -keep-temps``, to run within gdb debugger
- ``-lldb`` is equivalent to ``-wrapper "lldb --" -keep-temps``, to run within lldb debugger
-- ``-vgdb`` is equivalent to ``-wrapper "valgrind --vgdb=yes --vgdb-error=0"
--keep-temps``, to run within valgrind and allow to attach a debugger
+- ``-vgdb`` is equivalent to ``-wrapper "valgrind --vgdb=yes --vgdb-error=0" -keep-temps``,
+ to run within valgrind and allow to attach a debugger
To help locate bottlenecks and largest allocations in the simulated application,
the -analyze flag can be passed to smpirun. It will activate
iterations. These samples are done per processor with
SMPI_SAMPLE_LOCAL, and shared between all processors with
SMPI_SAMPLE_GLOBAL. Of course, none of this will work if the execution
-time of your loop iteration are not stable.
+time of your loop iteration are not stable. If some parameters have an
+incidence on the timing of a kernel, and if they are reused often
+(same kernel launched with a few different sizes during the run, for example),
+SMPI_SAMPLE_LOCAL_TAG and SMPI_SAMPLE_GLOBAL_TAG can be used, with a tag
+as last parameter, to differentiate between calls. The tag is a character
+chain crafted by the user, with a maximum size of 128, and should include
+what is necessary to group calls of a given size together.
This feature is demoed by the example file
`examples/smpi/NAS/ep.c <https://framagit.org/simgrid/simgrid/tree/master/examples/smpi/NAS/ep.c>`_
