PT - OS performance Monitoring using VMSTAT

 

PT - OS performance Monitoring using  VMSTAT 

vmstat

process ---- Memory ---- swap ---- i/o ----- system ----  cpu 

Process : r | b

Memory : spwd | spwd | free | buffer | cache

Swap : si | so

I/O:  bi | bo

System : cs | us | sy 

CPU : id |wt | st 

Field

Meaning

r

number of processes waiting for run time

b	number of processes in uninterruptible sleep

spwd

Virtual memory swapped out to disk

spwd

Virtual memory swapped out to disk

free

Amount of free memory

si	Amount of memory swapped in from disk
so	Amount of memory swapped to disk
us	User CPU time
bi	Blocks received from a block        device (blocks/s)
bo	Blocks sent to a block device
sy	System CPU time
id	CPU idle time

• vmstat command output example 

• vmstat 2 ( output every 2 second)

• Example to apply load on OS by executing i/o 30 times using apply_io_stress.sh file.

cat > apply_io_stress.sh <<EOL

#!/bin/bash

counter=1

while [ \$counter -le 30 ]

do

dd if=/dev/zero of=/tmp/test1.img bs=500M count=1 oflag=dsync

((counter++))

done

rm -f /tmp/test1.img

EOL

• Provide execute permission below.

chmod +x apply_io_stress.sh

srv1:~ # sh apply_io_stress.sh

^Z

[1]+  Stopped                 sh apply_io_stress.sh

srv1:~ #

• We can see after executing sh file number of r b  process increases also I/O bi bo  reading blocks and write block increase.

^Z

[1]+  Stopped                 sh apply_io_stress.sh

• Once stopping apply_io_stress.sh file processes and I/O value came back to normal.

vmstat -d 2

• vmstat -d 2 ( Disk output at every 2 seconds) Examples below.