On Wed, Jul 15, 2009 at 2:26 PM, Igor R <boost.lists@gmail.com> wrote:

> If this is a compiler flag, then can you try full build with
>
> cxxflags=-MP
>
> and then without and report the timings? If this is a magic way to make
> builds faster, it can be enabled by default.

It is a compiler flag, and it really improves build times in milticore
environment, but it's somewhat limited:
http://msdn.microsoft.com/en-us/library/bb385193.aspx

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). When you can build 4 or 8 source files simultaneously, that's a lot better than these two features, which do not speed up the build quite as much as this feature does. Additionally, this feature provides an increase in build speed without the disadvantages of using PCH and other alternatives.

I think that /MP should be made a default, but give the user the ability to disable it JUST in case they need to use any of the documented incompatible language features. That's just my two cents.