#
top
You can see Linux CPU utilization under CPU stats. The task’s share of the elapsed CPU time since the last screen update, expressed as a percentage of total CPU time. In a true SMP environment (multiple CPUS), top will operate in number of CPUs. Please note that you need to type q key to exit the top command display.
The top command produces a frequently-updated list of processes. By default, the processes are ordered by percentage of CPU usage, with only the "top" CPU consumers shown. The top command shows how much processing power and memory are being used, as well as other information about the running processes.
# sysstat
# mpstat
If you are using SMP (Multiple CPU) system, use mpstat command to display the utilization of each CPU individually. It report processors related statistics. For example, type command:
# mpstat
-----------------------------
Linux 2.6.15.4 (debian) Thursday 06 April 2006
05:13:05 IST CPU %user %nice %sys %iowait %irq %soft %steal %idle intr/s
05:13:05 IST all 16.52 0.00 2.87 1.09 0.07 0.02 0.00 79.42 830.06
-----------------------------
# mpstat -P ALL
Shows all the CPU's processing details.
CPU utilization using sar command
You can display today’s CPU activity, with sar command:
# 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
-----------------------------# sar -u 2 5
Where,
- -u 12 5 : Report CPU utilization. The following values are displayed:
- %user: Percentage of CPU utilization that occurred while executing at the user level (application).
- %nice: Percentage of CPU utilization that occurred while executing at the user level with nice priority.
- %system: Percentage of CPU utilization that occurred while executing at the system level (kernel).
- %iowait: Percentage of time that the CPU or CPUs were idle during which the system had an outstanding disk I/O request.
- %idle: Percentage of time that the CPU or CPUs were idle and the system did not have an outstanding disk I/O request.
# sar -o output.file 12 8 >/dev/null 2>&1 &
Better use nohup command so that you can logout and check back report later on:# nohup sar -o output.file 12 8 >/dev/null 2>&1 &
All data is captured in binary form and saved to a file (data.file). The data can then be selectively displayed ith the sar command using the -f option.
# sar -f data.file
Finally, you need 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
-----------------------------
%CPU PID USER COMMAND
96 2148 kiran /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]
-----------------------------
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