oracle 8.1.7 and advance server linux

i just want to know how the cpu idle time is below 10%

when I execute a sar command i get this output
03:40:00 PM CPU %user %nice %system %idle
03:50:00 PM all 91.01 0.04 7.99 0.96
04:00:00 PM all 91.92 0.04 7.36 0.69
04:10:00 PM all 90.49 0.04 8.68 0.80
04:20:00 PM all 92.31 0.03 6.83 0.82
04:30:00 PM all 91.01 0.03 8.85 0.11
04:40:00 PM all 91.36 0.04 8.51 0.08
04:50:00 PM all 92.08 0.04 7.81 0.06
05:00:00 PM all 91.70 0.03 8.22 0.05
05:10:00 PM all 90.59 0.05 9.27 0.10
05:20:00 PM all 91.63 0.04 8.28 0.06
05:30:00 PM all 90.09 0.04 9.80 0.07
05:40:00 PM all 89.71 0.03 10.17 0.09
05:50:01 PM all 89.61 0.04 10.23 0.12
06:00:01 PM all 89.71 0.03 9.65 0.61
06:10:00 PM all 90.55 0.04 8.82 0.59
06:20:00 PM all 89.40 0.03 9.94 0.62
06:30:00 PM all 89.36 0.04 9.76 0.84
06:40:00 PM all 88.86 0.04 10.44 0.66
06:50:01 PM all 90.13 0.04 9.27 0.56
07:00:00 PM all 89.11 0.04 10.23 0.63
07:10:00 PM all 89.14 0.04 10.21 0.61
07:20:00 PM all 89.94 0.03 9.44 0.58
07:30:01 PM all 89.43 0.04 9.97 0.55
07:40:00 PM all 90.33 0.05 8.98 0.64
07:50:00 PM all 89.91 0.04 9.31 0.74
08:00:00 PM all 90.41 0.05 8.82 0.72
08:10:00 PM all 90.09 0.04 9.33 0.55
08:20:00 PM all 87.84 0.03 11.17 0.95

well i looked at the backend , file system free space is there, tablespace free size is there , free memmory is also there what could be the issue ?

[oracle@ORACLEAS bdump]$ free -m
total used free shared buffers cached
Mem: 3851 3836 14 1006 193 1448
-/+ buffers/cache: 2194 1657
Swap: 2047 622 1425


[oracle@ORACLEAS bdump]$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/cciss/c0d0p5 4.8G 884M 3.6G 19% /
/dev/cciss/c0d0p1 116M 14M 96M 13% /boot
/dev/cciss/c0d0p3 43G 25G 16G 59% /home1
/dev/cciss/c0d0p2 44G 4.5G 37G 11% /home2
none 1.9G 0 1.8G 0% /dev/shm
/dev/cciss/c0d0p9 482M 8.1M 449M 2% /tmp
/dev/cciss/c0d0p6 3.8G 1.1G 2.5G 30% /usr
/dev/cciss/c0d0p8 1.4G 93M 1.2G 7% /var