[jamming] Jam2.5 and precompiled headers

[Matt Armstrong]

"Chris Antos" <chrisant at windows.microsoft.com> writes:

> I said you get maximum win from batch compilation WHEN YOU USE
> PRECOMPILED HEADERS.  :-)  (caps to add visibility to key point)

Interestingly, I see performance gains of 70-80% when a whole library
is turned into a single .c file (e.g. add one .c file that #includes
all the others and compile that).

Unfortunately this doesn't always work, given the semantics of a C
compilation unit.


> Between batch compilation and precompiled headers, the latter gives
> a bigger win.  Combining the two gains some additional improvements

I've also looked into trying to get visual c++ to support parallel
builds (-j 2).  Unfortunately, the compiler barfs because it wants to
build a .pdb file.  :-(