Re: [Boost-users] Building boost faster: /MP

Subject: Re: [Boost-users] Building boost faster: /MP
From: Robert Dailey (rcdailey_at_[hidden])
Date: 2009-07-15 16:54:51

On Wed, Jul 15, 2009 at 3:37 PM, Igor R <boost.lists_at_[hidden]> wrote:

> > Yes, it is limited in that it does not support a couple of other flags
> > simultaneously.
> > However, if you think about it, /MP is a replacement of /Gm (Incremental
> > Build) and /Yc (Precompiled Headers).
>
> IMHO, it's much more disappointing that /MP has almost no effect with
> /LTCG (and /GL). With these switches no much work is done in "compile"
> time - actual compilation occurs in the link-time, in one single
> process.

/MP is most valuable to the preprocessor, especially when using Boost in
your project. When you use boost in almost every single file, on a very
powerful machine you could still end up waiting 1-3 seconds for each file to
compile. This is, of course, subject to what part(s) of boost you're using.
In short, I think /MP introduces extreme performance improvements at most,
and no benefit at all at least.  It might not be perfect, but it's a very
good first step for Microsoft.