Compute the good number of cpu workers when master-slave is activated

src/core/topology.c

@@ -1331,7 +1331,17 @@ _starpu_init_machine_config(struct _starpu_machine_config *config, int no_mp_con
 			for (j = 0; j < STARPU_MAXMICDEVS; j++)
 				mic_busy_cpus += (topology->nmiccores[j] ? 1 : 0);
 
-			unsigned already_busy_cpus = mic_busy_cpus + topology->ncudagpus
+            unsigned mpi_ms_busy_cpus = 0;
+#ifdef STARPU_USE_MPI_MASTER_SLAVE
+#ifdef STARPU_MPI_MASTER_SLAVE_MULTIPLE_THREAD
+            for (j = 0; j < STARPU_MAXMPIDEVS; j++)
+                mpi_ms_busy_cpus += (topology->nmpicores[j] ? 1 : 0);
+#else
+            mpi_ms_busy_cpus = 1; /* we launch one thread to control all slaves */
+#endif
+#endif /* STARPU_USE_MPI_MASTER_SLAVE */
+
+			unsigned already_busy_cpus = mpi_ms_busy_cpus + mic_busy_cpus + topology->ncudagpus
 				+ topology->nopenclgpus + topology->nsccdevices;
 
 			long avail_cpus = (long) topology->nhwcpus - (long) already_busy_cpus;