[webkit-dev] WebCore Build Times

[Dirk Pranke]

On Tue, Jun 8, 2010 at 3:21 PM, Peter Kasting <pkasting at google.com> wrote:
>
> On Tue, Jun 8, 2010 at 3:17 PM, Eric Seidel <eric at webkit.org> wrote:
>>
>> Has anyone spent any time trying to reduce the number of includes in
>> WebCore?  I know we have:
>> https://trac.webkit.org/browser/trunk/WebKitTools/Scripts/find-extra-includes
>>
>> But I feel like we still have way too many unnecessary includes.  I
>> failed to find any tools for reducing build times or includes with my
>> brief Google searching.  But perhaps others have looked into this
>> problem for WebKit or other projects?
>
> I know someone once suggested that the build would be sped up if the #includes had longer paths (something like what happens in the Chromium tree) so that the toolchain didn't have to spend as much time scanning the (large) number of different directories on the #include path list.  However, I don't know how true this is, and plus, converting all the files to use this method would be a huge change (presumably done via a script).  I imagine removing unnecessary #includes, as you suggest above, would provide a much bigger benefit.

In a previous job, I spent a lot of time optimizing build times and
reducing the number of include directories scanned made an enormous
difference. However, that was C, not C++, and so the compilation and
link steps were much faster than the preprocessing step (compared to
C++, at least).

I would still expect the file system scanning to be much slower than
the actual preprocessing, so fixing include paths would probably still
make a bigger difference than reducing unnecessary includes, but I'm
not sure how much difference either contributes to the overall
numbers.

-- Dirk