a good method to estimate tu number of CPU used by a database 10gR2

 hi,

I try to calculate the number of CPU used by my database 10gR2/AIX 5.3.

To do that, i use the V$SYS_TIME_MODEL.DB CPU view. Every 60s, I catch the value. I get this :

TPS	VAL2
03/15/2010 14:16:35	4 135 544 925
03/15/2010 14:15:29	4 130 584 792
03/15/2010 14:14:29	4 127 171 066
03/15/2010 14:13:29	4 124 511 808
03/15/2010 14:12:29	4 122 359 695
03/15/2010 14:11:29	4 110 312 219
03/15/2010 14:10:28	4 100 555 420
03/15/2010 14:09:28	4 096 417 214
03/15/2010 14:08:28	4 092 871 892
03/15/2010 14:07:28	4 090 567 017
03/15/2010 14:06:28	4 088 155 539
03/15/2010 14:05:28	4 084 864 310

by example to calculer le number of CPU between 14:05:28 and 14:06:28 :

(4 088 155 539 - 4 084 864 310)/1000000< 1CPU (rule : 1 CPU = 60s)

Is it a good method or not ?

is a good method ?