Inconsistent CPU Usage from sar & top

Claude Lindo clindo at fsl.org.jm
Tue Jun 19 18:21:21 UTC 2007


Hi,

I use both sar and top to monitor system resource utilization my RHEL 4
servers, but I notice that they report different CPU statistics for the
same time period, e.g:
> sar 1 5 
17:00:01 CPU %user %nice %system %iowait %idle
17:00:02 all 20.00 0.00   5.00   75.00  0.00
17:00:03 all 22.00 0.00   6.00   72.00  0.00
17:00:04 all 15.00 0.00   9.00   76.00  0.00
17:00:05 all 13.00 0.00   5.00   82.00  0.00
17:00:06 all  7.00 0.00   3.00   90.00  0.00
Average: all 15.40 0.00   5.60   79.00  0.00

> top
top - 17:00:07 up 13 days, 9:56, 22 users, load average: 0.95, 0.88,
0.91
Tasks: 176 total, 2 running, 173 sleeping, 0 stopped, 1 zombie
Cpu(s): 8.1% us, 11.8% sy, 0.0% ni, 75.5% id, 4.4% wa, 0.1% hi, 0.1% si

PID    USER   PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 
3267  informix 17 0 3052 1176 748 S 11.1 0.2 6:46.73 top 
14729 root     16 0 2736 896  660 R  3.7 0.2 0:00.05 top 
2656 informix  15 0 213m 166m 165m R 1.9 33.0 535:39.68 oninit 
2660 root 15 0 213m 141m 141m S 1.9 28.1 43:36.36 oninit 
1 root 16 0 1788 516 460 S 0.0 0.1 0:05.61 init 
2 root 34 19 0 0 0 S 0.0 0.0 0:00.18 ksoftirqd/0 
3 root 5 -10 0 0 0 S 0.0 0.0 0:00.11 events/0 

This happens on several servers and across time periods. The two utils
report different CPU usage stats; which one is correct or is it that I
am using them incorrectly?

Claude.




More information about the redhat-sysadmin-list mailing list