modify collective overhead parameter to best guess value

src/network-workloads/model-net-mpi-replay.c

@@ -74,8 +74,8 @@ int num_traces_of_job[5];
 tw_stime soft_delay_mpi = 1250;
 tw_stime nic_delay = 250;
 tw_stime copy_per_byte_eager = 0.55;
-tw_stime col_overhead_per_byte = 0.8;
-tw_stime col_soft_overhead = 6000;
+tw_stime col_overhead_per_byte = 0.7;
+tw_stime col_soft_overhead = 6600;
 char file_name_of_job[5][8192];
 
 struct codes_jobmap_ctx *jobmap_ctx;