Re: The right configuration mechanism

From: David Abrahams (dave_at_[hidden])
Date: 2005-08-16 08:40:15

Andrey Melnikov <melnikov_at_[hidden]> writes:

>>>>Except execution time. IIRC, SCons used to search for all tools it knows
>>>>about and it was a performance problem. OTOH, we'll be searching just for
>>>>a few compilers, and not for bison/lex/f77 and whatnot.
>>>
>>>AFAIK, now if I have 10 using rules in user-config, 10 toolset files are
>>>parsed and 10 init rules are executed even if I build only with a single
>>>toolset. Is this true?
>> 
>> 
>> Yes. 
>
> I wonder how much time for incremental builds we will save if we won't 
> use full evaluation? From my measurements it seems that we won't save 
> too much - an incremental build of a project consisting of 3 targets and 
> 5 cpp files takes less than 3 seconds on my old 900mhz box. But I only 
> have 3 toolsets configured: MSVC 7.1, 8.0 and BCB.

I built a profiler into bjam (-d+10, I think?) so you can easily
verify what percentage of the time is spent in configuration, and
Volodya regularly looks at timing for slow builds to discover where
the bottlenecks are. I suggest we not spend any more time worrying
about it here until we have solid numbers suggesting it's an issue.

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com