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How to Change Process Priority using Linux Nice and Renice

Posted by shazim on 07 02 2017. 0 Comments

In a Linux system, there are hundred’s of processes, that are continuously running diffrents tasks. Linux Kernel does a fantastic job in mediating between these processes and allotting CPU to these processes.

Every running process in Linux has a priority assigned to it.We can change the process priority using nice and renice utility.

With the help of Nice command in Linux you can set process priority. If you give a process a higher priority, then Kernel will allocate more cpu time to that process.

Nice command will launch a process with an user defined scheduling priority. Renice command will modify the scheduling priority of a running process.Linux Kernel schedules the process and allocates CPU time accordingly for each of them.

he process scheduling priority range is from -20 to 19. We call this as nice value.

A nice value of -20 represents highest priority, and a nice value of 19 represent least priority for a process.

Follow the below process to increse the priority of any process.

1 ) Login into your Linux system via user name and password , enter # top command.

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After hiting enter you will get output like above screen, in that NI means Nice Value of perticular prcess .

2 ) We can set NI value of any process or command in 2 way.

i ) In the outout of # top command , just enter ” r ” , we get the screen like below.

By default when a programe is launched in Linux, it gets launched with the priority of ‘0’. However you can change the priority of your service yourself.

 

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Simply just put the PID of any process , or the PID of that process which you want to increse the priority. Hit enter after putting PID.

 

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It will ask for Renice value , see the above screen. put the value priority range is from -20 to 19. We call this as nice value.A nice value of -20 represents highest priority, and a nice value of 19 represent least priority for a process.

After putting renice value , the process priority will change accodring to NI value.

check the NI coloum after purring renice value of any process , see below screen

 

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In the above screen PID of kthreadd is 2 and its nice valur has been changed to -10 , means now it has higher priority among then all process , which is running under Linux system.

We can also set the NI nice value of any process like httpd, java , mysql , ftp , sshd to make that service perform fast.

ii ) We can set NI via another way , by using simple below command

After top command , do the below step to increase performance of any service, or process

# nice -10 httpd

Above commmand will set NI valur of httpd service to 10 , means it has lower priority among all the running process under linux system.

# nice –10 httpd

Above command will set Ni value of httpd service to -10 , means it has highest priority , we can incresre this value ti -20 , A nice value of -20 represents highest priority.

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