Re: [PATCH 0/4] Compile kernel with -fwhole-program --combine

From: David Woodhouse <dwmw2@infradead.org>
To: Sam Ravnborg <sam@ravnborg.org>
Cc: Jan Engelhardt <jengelh@linux01.gwdg.de>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/4] Compile kernel with -fwhole-program --combine
Date: Fri, 25 Aug 2006 11:14:53 +0100	[thread overview]
Message-ID: <1156500893.2984.70.camel@pmac.infradead.org> (raw)
In-Reply-To: <20060825072654.GC30453@uranus.ravnborg.org>

On Fri, 2006-08-25 at 09:26 +0200, Sam Ravnborg wrote:
> And this discussion is btw. mood. If the general opinion is that we shall
> include the -combine support all the kbuild infrastructure will anyway
> be redone.
> There are several small things that are not addressed in todays
> implementation and that will be fixed one way or the other.

There's a few _big_ things that aren't addressed in my makefile hack
either. It's very much a proof of concept.

However, if we limit the use of --combine to files within the same
directory, the modifications to the kbuild infrastructure shouldn't be
too intrusive. I strongly suspect that files within the same directory
are where the majority of the benefit is anyway.

Whole-kernel optimisation is likely to be prohibitively expensive, and
can wait for LTO¹.

-- 
dwmw2
¹ http://www.gelato.org/pdf/apr2006/gelato_ICE06apr_lto_mitchell_codesourcery.pdf