From: Raffaele Belardi <raffaele.bela...@st.com>
Sent: Wednesday, November 22, 2017 8:12 AM
To: gentoo-user@lists.gentoo.org
Subject: Re: [gentoo-user] is multi-core really worth it?

Jeremi Piotrowski wrote:
> That being said: if you do a world rebuild you will have lots of packages
> that spend ~40 seconds doing their autoconf run, only to build 2-3 sources
> files. On an 8-core machine at work, I get good results using parallel
> emerge jobs (emerge -jX). For your 6-core AMD CPU (assuming it actually
> has 12 threads) I'd start with 'emerge -j3' and MAKEOPTS='-j12 -l16'.
> That should get you a nice speedup, but may require a bit more ram.

emerge -j3 is something I did not think of, I'll try it. But won't that break 
portage's
carefully crafted package dependencies? I suppose you could get occasional 
build failures?

I'm using MAKEOPTS=-j7, I thought 2 threads per CPU (hyperthreading?) was an 
Intel thing only.

raffaele


There are alot of good tweaks to get by long configure sections, I have an octa 
core, so for normal updates I use -
MAKEOPTS="-j8" # for 8 cores being used per package
EMERGE_DEFAULT_OPTS="--jobs 2 --load-average 4" # only starts 2nd job if load 
average is low.

You won't get build failures or dependency problems, portage is built to handle 
emerging multiple packages that do not depend on each other simultaneously.
it will not ever build a dependency and the main program at the same time.

PORTAGE_NICENESS="19" # best setting ever, I do some gaming while updating, you 
mainly only notice install phase if your are loading while the disk queue is 
full of writes.


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