Master Linux Monitoring: CPU, Memory, Disk & Network Using vmstat, iostat, pidstat

CPU Usage Monitoring

Run the graphical tool gnome-system-monitor to view real‑time CPU utilization, memory usage and process information.

# gnome-system-monitor

CPU Scheduler Run Queue with vmstat

vmstat

(Virtual Memory Statistics) reports real‑time system metrics. Basic syntax: vmstat [delay [count]] Parameters :

delay : interval in seconds between two samples.

count : number of samples to collect; must be used together with delay .

When called without arguments, vmstat shows averages since boot. With a delay , the first line is the average since boot; subsequent lines show averages for each interval.

Key fields (derived from /proc/stat) relevant to CPU:

r : number of tasks waiting for CPU (run queue, excludes the vmstat process).

b : number of blocked tasks (I/O, paging, etc.).

us : user‑mode CPU time (%).

sy : kernel‑mode CPU time (%).

id : idle time (%), not counting I/O wait.

wa : I/O wait time (%).

in : interrupts per second.

cs : context switches per second.

# vmstat

Lock Contention Monitoring with pidstat

The pidstat command from the sysstat package reports per‑process CPU usage, useful for spotting lock‑related bottlenecks.

# pidstat

Typical columns: PID, %usr, %system, %guest, %CPU, CPU (core), Command.

Network I/O Monitoring with nicstat

nicstat

(originally from Solaris) displays per‑interface transmit/receive rates and packet statistics on Linux.

Installation steps (tested with version 1.92):

# yum install gcc gcc-c++ make automake autoconf -y
# yum install libgcc.i686 glibc.i686 glibc-devel.i686 -y
# wget -c http://nchc.dl.sourceforge.net/project/nicstat/nicstat-1.92.tar.gz
# tar zxvf nicstat-1.92.tar.gz
# cd nicstat-1.92
# cp Makefile.Linux Makefile
# make

# ./nicstat.sh

Disk I/O Monitoring with iostat

iostat

reports CPU and block‑device statistics.

Basic syntax: iostat [-t] [-c] [interval [count]] Parameters :

-t : include timestamp in output.

-c : display only CPU information.

interval : seconds between samples.

count : number of samples (requires interval ).

When run without arguments, iostat shows averages since system boot. With an interval , the first line is the overall average; subsequent lines reflect each interval.

Key CPU fields (derived from /proc/stat) reported by iostat:

user : user‑mode CPU time (%), excluding negative nice values.

nice : CPU time for processes with negative nice value (%).

sys : kernel‑mode CPU time (%).

iowait : time waiting for I/O (%).

idle : idle time (%), not counting I/O wait.

# iostat

Additional Resources

For deeper Linux performance analysis, see Brendan Gregg’s collections:

https://www.brendangregg.com/linuxperf.html

http://www.cnblogs.com/argb/p/3448661.html

http://blog.yufeng.info/archives/2518