linuxgeek: Re: [LINUX_Newbies] experiences with nice

Friday, April 4, 2014

Re: [LINUX_Newbies] experiences with nice

On 05Apr2014 07:30, highskywhy@yahoo.de <highskywhy@yahoo.de> wrote:
> So yesterday I started all software with nice
>
> nice gedit
> nice firefox
> nice chrome
> nice thunderbird and so on
>
> I expected
> now all is more
>
> slow
> and more relaxed.
>
> BUT
>
> all is now
> more fast and more relaxed.
>
> Is this true or is this my imagination?

Could be your imagination, but possibly not.

Firstly, niceness does not slow things down.
It arranges that when multiple processes want CPU, the ones with
higher "nice" values get a smaller share of the CPU.

So if everything is niced, they should all get the same share of
the CPU as if nothing were niced.

Also, if you aren't using much CPU, then the niceness has little
effect because everyone gets enough CPU anyway.

HOWEVER, you haven't started everything with nice.
In particular, your desktop window system is _not_ reniced.
Only the main applications you're running (firefox etc) are nicer.

This means that IF you are using most of your CPUs, then the desktop
window system will get more CPU than your applications (other things
being equal - assuming they both want CPU at the same time).

It is _possible_ that this results in smoother "feel" of your
desktop, because it gets more CPU and the apps less CPU: that makes
it render faster (assuing it was being slowed up before) and makes
them ask for things to render less (because they get less CPU to
cause changes).

It bears repeating that this situation is unusual unless you really
are running something intensive (converting video file formats or
something). If you see smoother behaviour by renicing your apps,
then there is not enough CPU going around. On a modern machine,
that often means something is wrong.

Your other post about firefox and chrome using 70% and 80% or the
CPU may be indicative. Try to find out what is using your CPU, and
then find out why. If it is a browser, probably it is a plugin like
adobe flash. If you don't know, open top in one window and carefully
close browser windows one at a time until top shows the browser
sudden using less CPU.

Here, "carefully" means: pay attention to what is on the page before
you close it. That way, if a particular page stops using the CPU
you will know which page it was and probably why.

Cheers,
--
Cameron Simpson <cs@zip.com.au>

Yesterday it worked
Today it is not working
Windows is like that
- Haiku Error Messages http://www.salonmagazine.com/21st/chal/1998/02/10chal2.html