----- Original Message ----
From: "fortin.pierre@bell.ca" fortin.pierre@bell.ca To: centos@centos.org Sent: Thu, January 14, 2010 5:47:43 PM Subject: Re: [CentOS] High load since passing from rhas3 to centos4.8
The purpose of the server is to run NMS Telephony cards. The only support is for Centos 4.x on 32 bit systems. Anyway, since I have not found the trouble, it may still be there with another centos version.
When I execute multiple ps during high load average period (above 10), here is the kind of output I have:
ps aux | grep " R" USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 16295 0.0 0.0 3492 772 pts/1 R+ 15:45 0:00 ps -aux root 16296 0.0 0.0 5400 648 pts/1 S+ 15:45 0:00 grep R
I see a lot of process in S, Sl, Ss+ and Ssl states.
first of all, if you have high load average with seemingly low utilization, it may be because of load imbalance between CPUs and/or short bursts of lots of short cpu-intensive processes.
Here's what I'd look at first:
run "vmstat 1 10" and look at the first column. if it's higher than 1/ncpu you're having cpu saturation.
rum "mpstat -P ALL 1 10", this gives you cpu utilisation per cpu (sar gives you the average among all processors)
Also take a look at "sar -q 1 10" to look at the CPU's queues sizes
Hope this helps
Fer