Arch Linux

kayrune

Member

Registered: 2007-12-15

Posts: 43

compile packages yourself with dual/quad core

I'm compiling some packages and svn myself and I'm wondering, why 'make' only use one of the 4 cores on the cpu ? is there som way to make it use all four ? I'd assume compiling would be a lot faster.

kappa

Member

Registered: 2006-11-10

Posts: 26

Re: compile packages yourself with dual/quad core

Make's "-j" option controls how many jobs make can execute at the same time. Makepkg defaults to -j 2 (set under MAKEFLAGS in /etc/makepkg.conf ).

skottish

Forum Fellow

From: Here

Registered: 2006-06-16

Posts: 7,942

Re: compile packages yourself with dual/quad core

This can break some software from compiling, and it will fail without warning.

dyscoria

Member

Registered: 2008-01-10

Posts: 1,007

Re: compile packages yourself with dual/quad core

Yeah, some argue that '-j 3' is fine, but many have come across problems with anything but the default '-j 2 'which happens to be very safe.

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Misfit138

Misfit Emeritus

From: USA

Registered: 2006-11-27

Posts: 4,189

Re: compile packages yourself with dual/quad core

I personally use -j3 for my SMP. I have not had a problem yet, though, it is widely perceived that -j2 is safest and I'm not arguing.

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Sauengard

kappa

Member

Registered: 2006-11-10

Posts: 26

Re: compile packages yourself with dual/quad core

This can break some software from compiling, and it will fail without warning.

On multi-core systems this already happens with the default -j2. There one might have to explicitly set -j1 for some builds, but I have yet to see a program that would build with -j2 but not -j3 or -j4.

schivmeister

Developer/TU

From: Singapore

Registered: 2007-05-17

Posts: 971

Website

Re: compile packages yourself with dual/quad core

-j5 on a Core 2 Duo is fine, while -j10 on a Quad works Well, at least according to some ricers.

-j1, for a case example, is required for compiling anything VST-related.

When you come across a build that fails with regards to job servers, take a look at the default makefile. Few will tell you that > make=-jn will not work. This was discussed to a little extent here.

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brebs

Member

Registered: 2007-04-03

Posts: 3,742

Re: compile packages yourself with dual/quad core

See race condition, for why 1 thread works, and >1 maybe won't.