#condition :
# int Nsd=10000;
#int Nttmax=200;
#int Nnode=2000;
#int nb_seed=1000;
#nb proc	time 1000	speed up 1000	ideal speed up	time 1
#   speed up 1

1   		49212		1     		1     	    	42157.6		1
2   		24966.6		1.971		2		21441.4		1.966
4   		13079.9		3.762		4		11184.1		3.769
8   		6602.13		7.453		8		5651.4		7.459
16  		3633.65		13.543		16		2981.5		14.139
32  		1960.88		25.096		32		1609.62		26.191