I read a discussion on LowEndBox, where a VPS user was suspended because his CPU usage was more than the allowed load. So I tried to ascertain how to find the load on my VPS.
The command top and htop can show current stats:
Install htop with:
Debian
apt-get install htop
Centos 6
wget http://pkgs.repoforge.org/htop/htop-1.0.2-1.el6.rf.x86_64.rpm rpm -Uvh htop-1.0.2-1.el6.rf.x86_64.rpm rm htop-1.0.2-1.el6.rf.x86_64.rpm
Run it:
htop
Note the top right stats which show the average load on the CPU. 1 here is roughly equivalent to utilization of one core (I think). The CPU% coloumn shows the load due to each process.
The command mpstat also shows the CPU load of each core.
To get a total load report:
mpstat Linux 2.6.32-042stab072.10 (hermes) 04/13/13 _x86_64_ (8 CPU) 12:45:14 CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle 12:45:14 all 1.07 0.00 0.11 0.02 0.00 0.00 0.02 0.00 98.78
And to get it broken down per core:
mpstat -P ALL Linux 2.6.32-042stab072.10 (hermes) 04/13/13 _x86_64_ (8 CPU) 12:46:03 CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle 12:46:03 all 1.07 0.00 0.11 0.02 0.00 0.00 0.02 0.00 98.79 12:46:03 0 1.91 0.00 0.17 0.01 0.00 0.00 0.03 0.00 97.89 12:46:03 1 1.30 0.00 0.16 0.01 0.00 0.00 0.02 0.00 98.51 12:46:03 2 0.49 0.00 0.04 0.00 0.00 0.00 0.01 0.00 99.45 12:46:03 3 0.58 0.00 0.05 0.04 0.00 0.00 0.02 0.00 99.31 12:46:03 4 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 12:46:03 5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 12:46:03 6 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 12:46:03 7 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
You can also enable data collection by editing the file.
By default, it is:
egrep -v '^#|^$' /etc/default/sysstat ENABLED="false" SA1_OPTIONS="-S DISK" SA2_OPTIONS=""
I used egrep to filter out blank and comment lines.
Change the ENABLED= value to true.
Note: To run sar to monitor the system activity, you need to first enable it with:
dpkg-reconfigure sysstat
Else you get the error message:
#sar Cannot open /var/log/sysstat/sa13: No such file or directory Please check if data collecting is enabled in /etc/default/sysstat
Now start the service with:
/etc/init.d/sysstat start Starting the system activity data collector: sadc.
Now to see the collected data:
sar -A Linux 2.6.32-042stab072.10 (hermes) 04/13/13 _x86_64_ (8 CPU) 18:34:16 LINUX RESTART
That is only a default clean log. I’ll need to repeat the command after some time to get useful information
To check CPU load at intervals of 5 seconds, and report 10 different checks:
sar -u 5 10 Linux 2.6.32-042stab072.10 (hermes) 04/13/13 _x86_64_ (8 CPU) 18:41:24 CPU %user %nice %system %iowait %steal %idle 18:41:29 all 0.85 0.00 0.10 0.00 0.05 99.00 18:41:34 all 0.05 0.00 0.05 0.00 0.00 99.90 18:41:39 all 0.05 0.00 0.05 0.00 0.00 99.90 18:41:44 all 0.00 0.00 0.05 0.00 0.00 99.95 18:41:49 all 0.05 0.00 0.05 0.00 0.00 99.90 18:41:54 all 0.05 0.00 0.10 0.00 0.00 99.85 18:41:59 all 0.95 0.00 0.10 0.05 0.00 98.90 18:42:04 all 1.50 0.00 0.30 0.00 0.00 98.19 18:42:09 all 2.20 0.00 0.35 0.00 0.05 97.39 18:42:14 all 0.70 0.00 0.20 0.00 0.00 99.10 Average: all 0.64 0.00 0.14 0.01 0.01 99.21
You can keep checking even when logged off, and get the final stats by scheduling such checks at predetermined frequencies and intervals, sending the process to the background:
nohup sar -o /root/cpustats.log 10 6 >/dev/null 2>&1 &
That takes care of reporting for 60 minutes, and checking every 10 minutes. Every 10 mins x 6 times = 60 minutes.
You can of course create a cron job to sample these data every N hourly.
Once the data is saved to this file, which incidentally is a binary file, you can get the report by:
sar -f /root/cpustats.log
To find the most resource consuming processes:
To get top 20 CPU hogging processes:
#ps -eo pcpu,pid,user,args | sort -k 1 -r | head -20 %CPU PID USER COMMAND 1.0 6386 vu2003 /usr/bin/php5-cgi 0.9 5930 vu2003 /usr/bin/php5-cgi 0.6 5680 vu2003 /usr/bin/php5-cgi 0.5 6412 vu2003 /usr/bin/php5-cgi 0.5 6061 vu2003 /usr/bin/php5-cgi 0.5 5913 vu2003 /usr/bin/php5-cgi 0.4 5932 vu2003 /usr/bin/php5-cgi 0.3 6063 vu2003 /usr/bin/php5-cgi 0.1 633 mysql /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --user=mysql --pid-file=/var/run/mysqld/mysqld.pid --socket=/var/run/mysqld/mysqld.sock --port=3306 0.0 6677 root head -20 0.0 6676 root sort -k 1 -r 0.0 6675 root ps -eo pcpu,pid,user,args 0.0 6674 sshd sshd: unknown [net] 0.0 6673 root sshd: unknown [priv] 0.0 6408 vu2003 /usr/bin/php5-cgi 0.0 5964 root /usr/bin/perl /var/www/imscp/engine/imscp-apache-logger 0.0 5934 postfix pickup -l -t fifo -u -c 0.0 5742 root -bash 0.0 5739 root sshd: [email protected]/0
To get all of them, one screenful at a time:
ps -eo pcpu,pid,user,args | sort -r -k1 | less