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Re: parallel make help
From: |
Ralf Wildenhues |
Subject: |
Re: parallel make help |
Date: |
Thu, 10 Apr 2008 22:54:27 +0200 |
User-agent: |
Mutt/1.5.17+20080114 (2008-01-14) |
Hi Bob,
* Bob Rossi wrote on Thu, Apr 10, 2008 at 03:28:56PM CEST:
> I currently have my project setup so that each subdirectory has a
> Makefile.am. I've noticed that when I do 'make -j4' that it does 1
> directory at a time, then links a little library or makes a program.
>
> If I moved everything to a single Makefile.am at the top level, would
> that improve the speed of things so that it could continue to build
> in parallel?
Typically yes, the other Bob already addressed this.
> If it is in fact faster, like I'm imagining it might be, is there any
> way to make the "Makefile.am in each subdir" approach be just as fast?
I've thought of this, in fact just a couple of weeks ago. It is
possible to formulate SUBDIRS rules in a way that allows parallel
execution of the sub makes (by something like turning each subdir
into a target). However, doing so by default will certainly break
lots of existing setups. That's why my current thinking is that
it may be possible to introduce a new feature, say,
PARALLEL_SUBDIRS = ...
which would then show automake that these subdirectories really
can do work in parallel. Maybe even get this functionality turned
on per-project with an automake option, dunno yet.
I haven't thought this through yet. There are some quite subtle
issues that users need to be aware of for this to work correctly.
> I eventually want to spread my build out over N machines using autotools
> and dist-gcc.
Do you mean distcc? That should work.
Cheers,
Ralf