mpi tests: use only 3 CPU workers

To leave some room for the MPI thread so the tests don't get awfully slow on machines with 4 cores.

mpi/examples/Makefile.am

@@ -47,10 +47,10 @@ endif
 endif
 
 if STARPU_HAVE_AM111
-TESTS_ENVIRONMENT	=	STARPU_WORKERS_NOBIND=1 STARPU_NCPU=4 top_builddir="$(abs_top_builddir)" top_srcdir="$(abs_top_srcdir)"
+TESTS_ENVIRONMENT	=	STARPU_WORKERS_NOBIND=1 STARPU_NCPU=3 top_builddir="$(abs_top_builddir)" top_srcdir="$(abs_top_srcdir)"
 LOG_COMPILER	 	=	$(MPI) $(LOADER_BIN)
 else
-TESTS_ENVIRONMENT 	=	STARPU_WORKERS_NOBIND=1 STARPU_NCPU=4 top_builddir="$(abs_top_builddir)" top_srcdir="$(abs_top_srcdir)" $(MPI) $(LOADER_BIN)
+TESTS_ENVIRONMENT 	=	STARPU_WORKERS_NOBIND=1 STARPU_NCPU=3 top_builddir="$(abs_top_builddir)" top_srcdir="$(abs_top_srcdir)" $(MPI) $(LOADER_BIN)
 endif
 
 if STARPU_MPI_CHECK

mpi/tests/Makefile.am

@@ -45,10 +45,10 @@ endif
 endif
 
 if STARPU_HAVE_AM111
-TESTS_ENVIRONMENT	=	STARPU_WORKERS_NOBIND=1 STARPU_NCPU=4 top_builddir="$(abs_top_builddir)" top_srcdir="$(abs_top_srcdir)"
+TESTS_ENVIRONMENT	=	STARPU_WORKERS_NOBIND=1 STARPU_NCPU=3 top_builddir="$(abs_top_builddir)" top_srcdir="$(abs_top_srcdir)"
 LOG_COMPILER	 	=	$(MPI) $(LOADER_BIN)
 else
-TESTS_ENVIRONMENT 	=	STARPU_WORKERS_NOBIND=1 STARPU_NCPU=4 top_builddir="$(abs_top_builddir)" top_srcdir="$(abs_top_srcdir)" $(MPI) $(LOADER_BIN)
+TESTS_ENVIRONMENT 	=	STARPU_WORKERS_NOBIND=1 STARPU_NCPU=3 top_builddir="$(abs_top_builddir)" top_srcdir="$(abs_top_srcdir)" $(MPI) $(LOADER_BIN)
 endif
 
 if STARPU_MPI_CHECK