Linux Performance trouble shooting

Linux Performance trouble shooting

Load Avg 1 min 5 min 15 min

CPU Script to hog the CPU

cpuhog.sh

while true

do yes > /dev/null

done

Disk hog io hog

dd if = /dev/sda of=dev/zero

%us : user space utlizttion started by user/application

%sy : system spce Kernel side utlization

%ni : nice -20 highest 90 is lowesr

%id : idle amount of time CPU is not doing anything

%si : time waiting for the CPU for the IO

%hi : Hardware inturupt

%si : Software inturrupt

%st : Referect stleth used for Virtual System

Cat /proc/interrupt

Load avg ( we will get the info from the following location)

cat /proc/lodavg

cat /proc/slabinfo | grep -i den

cat /proc/meminfo | grep -i slab (Kernel Memory usge )

Buffer consits of metatdata

cat /proc/slabinfo | grep -i den

How to check the dentry size

slabtop | grep -i den

Command to find the kernel Memory

cat /proc/meminfo | grep -i slab (Kernel Memory usge )

Cache app =====> ram (cache) ====> disk

CPU L1/L2/L3 cache =====> Cache====> disk

Command to check the L1 and L2 cache

Shared memory shared by diffrent process

pmap -i

command to free the cache memory (never run the same in the prod box)

sync && echo 3 > /proc/sys/vm/drop_caches (never run the same in the prod box)

to Free page cache dentries and inodes

echo 3

to free dentires and inodes

echo 2

to free page cache

ehco 1

lscpu | grep L1.l2 cache

command to find the which CPU is using for which processor

ps -eo pid,arfs,psr

Command to find the how many CPU are present

cat /proc/cpuinfo | grep -i processor