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→Debian/Ubuntu-specific: add Setting niceness (aka priority) on Linux processes
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== Setting niceness (aka priority) on Linux processes == | |||
*Tested on: Ubuntu 12.04 Precise | |||
*Difficulty: 1/10 | |||
*Time: <1 minute + your WPM | |||
Niceness or nice value in Linux is just another name for the value of priority given to a process. The higher the number means the lower the priority. The nice value can also be negative, and such values will give a process higher than normal priority. Higher the priority (or lower the nice value), the more CPU time is given, therefore the application will be perceived as running faster. | |||
As an example, let's say the process of interest is ''qemu-system-arm''. You have to find out what PID (Process ID) is first. | |||
<source lang="bash"> | |||
$ pidof qemu-system-arm | |||
3016 | |||
</source> | |||
Then check what the current nice value of the process is: | |||
<source lang="bash"> | |||
$ ps -o pid,comm,nice -p 3016 | |||
PID COMMAND NI | |||
3016 qemu-system-arm 0 | |||
</source> | |||
According to the output, the nice value of ''qemu-system-arm'' is 0. We want to '''decrease''' the nice value to dedicate more CPU time to it. However, you need sudo privilege in order to give a negative value for a nice value, even though you do not need such privilege for increasing the nice value to something above 0. Here we decrease it to -10. | |||
<source lang="bash"> | |||
$ sudo renice -10 -p 3016 | |||
</source> | |||
To set a permanent priority on all processes for a specific user or a group you can update ''/etc/security/limits.conf'' file. | |||
===References=== | |||
http://www.nixtutor.com/linux/changing-priority-on-linux-processes/ (accessed on July 22, 2012) | |||