Re: BB2 performance.

From: David Abrahams (dave_at_[hidden])
Date: 2005-07-30 18:39:48

Jim Tilander <jim.tilander_at_[hidden]> writes:

> Hi all,
>
> First, let me say that design of boost build looks very good, the features 
> available are an almost exact match for what I would say an ideal system for 
> describing building of source code. However, we've been conducting 
> performance analysis on boost build2 M10 inhouse and found that both the 
> build times and dependency checking seems to be considerably slower than 
> just plain vanilla jam, in fact it's on par or worse than scons, which seems 
> to be one of the slowest system out there. For a full rebuild it's around 
> twice as slow as vanilla jam (can this be due to the constant calling of 
> vcvars32.bat?) and for a dependency check (call build again without anything 
> changed) 18 (!) times slower than vanilla jam. 

It's very likely that most of the time isn't being consumed in
dependency checking but in the execution of the Jam code that builds
the dependency graph. A heck of a lot of processing goes on between
the high-level Jamfiles you write and the creation of low-level Jam
targets. When you use "vanilla jam" you are describing those
low-level targets directly, or very close to directly.

> The question is, can I somehow in a few easy steps tweak something
> or patch something so that the whole system runs a little bit
> faster? Any tips?

You can 

bjam -n -d+10 

to get a dump of the profiling data for that stuff. I doubt there are
any "easy steps," though.

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