[gentoo-user] Re: May be OT: recommended niceness settings for Portage while using Gnome?

[Nikos Chantziaras]

On 08/21/2009 07:54 PM, James Homuth wrote:
>
> I just got Gnome set up completely on a 5-year-old laptop with 512 MB of
> RAM running on a P4, and am sort of halfway in the middle of playing
> with it. In the process, I'm discovering I still need to install a few
> things. Just one problem. I emerge said things, and the system flatlines
> until such time as the compilation(s) are done--load is currently
> sitting at 2.1+. Are there any make.conf settings I can tweak so that I
> can still actually use the system while things compile, or would I be
> better off setting things to compile, throwing in a movie, and coming
> back when they're done? Thanks for any pointers.

Not sure if something changed in recent kernels, but 19 used to be the 
most efficient value since processes running at 19 are considered batch 
jobs.  They get plenty of CPU time due to longer time-slices 
(responsiveness suffers, but you don't care about portage being 
responsive in the first place, so it's optimal.)  So:

   PORTAGE_NICENESS=19

Is best.  However, also very important is "I/O nice".  Setting an ionice 
value of "idle" will result in portage not blocking your other 
applications whey they need to do disk I/O:

   PORTAGE_IONICE_COMMAND="ionice -c 3 -p \${PID}"

This needs a kernel newer than 2.6.16 and it has to be configured to use 
the CFQ scheduler.  You know if that's the case if this command:

   zgrep CFQ /proc/config.gz

says:

   CONFIG_IOSCHED_CFQ=y
   CONFIG_DEFAULT_CFQ=y