linux and unix system monitoring

To monitor the resource utilization of various aspects of linux systems we have various tools such as top, vmstat, iostat etc which can be installed from the package 'sysstat ' .

some of the example useful commands which can be used to monitor the resources are:

# mpstat -P ALL

procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy id wa
3  0      0   1963    607   2359    0    0     0     0    0     1 32  0 68  0

# sar

Linux 2.6.9-42.0.3.ELsmp (dellbox.xyz.co.in)         01/13/2007

12:00:02 AM       CPU     %user     %nice   %system   %iowait     %idle
12:10:01 AM       all      1.05      0.00      0.28      0.04     98.64
12:20:01 AM       all      0.74      0.00      0.34      0.38     98.54
12:30:02 AM       all      1.09      0.00      0.28      0.10     98.53
12:40:01 AM       all      0.76      0.00      0.21      0.03     99.00
12:50:01 AM       all      1.25      0.00      0.32      0.03     98.40
01:00:01 AM       all      0.80      0.00      0.24      0.03     98.92
...
.....
..
04:40:01 AM       all      8.39      0.00     33.17      0.06     58.38
04:50:01 AM       all      8.68      0.00     37.51      0.04     53.78
05:00:01 AM       all      7.10      0.00     30.48      0.04     62.39
05:10:01 AM       all      8.78      0.00     37.74      0.03     53.44
05:20:02 AM       all      8.30      0.00     35.45      0.06     56.18
Average:          all      3.09      0.00      9.14      0.09     87.68
To determine which process is monopolizing or eating the CPUs. Following command will displays the top 10 CPU users on the Linux system.
# ps -eo pcpu,pid,user,args | sort -k 1 -r | head -10
OR
# ps -eo pcpu,pid,user,args | sort -r -k1 | less
Output:
%CPU   PID USER     COMMAND
  96  2148 vivek    /usr/lib/vmware/bin/vmware-vmx -C /var/lib/vmware/Virtual Machines/Ubuntu 64-bit/Ubuntu 64-bit.vmx -@ ""
 0.7  3358 mysql    /usr/libexec/mysqld --defaults-file=/etc/my.cnf --basedir=/usr --datadir=/var/lib/mysql --user=mysql --pid-file=/var/run/mysqld/mysqld.pid --skip-locking --socket=/var/lib/mysql/mysql.sock
 0.4 29129 lighttpd /usr/bin/php
 0.4 29128 lighttpd /usr/bin/php
 0.4 29127 lighttpd /usr/bin/php
 0.4 29126 lighttpd /usr/bin/php
 0.2  2177 vivek    [vmware-rtc]
 0.0     9 root     [kacpid]
 0.0     8 root     [khelper]

references:

http://www.cyberciti.biz/tips/how-do-i-find-out-linux-cpu-utilization.html