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Subject: Re: [Boost-build] [Boost.Build] bjam takes very long before start of compilation (of boost iostreams)
From: Vladimir Prus (ghost_at_[hidden])
Date: 2008-10-06 07:29:15

On Monday 06 October 2008 13:21:55 Boris Dušek wrote:
> Hello,
> I am building boost 1.34.1 iostreams library using bjam 3.1.16-1-ntx86
> (downloaded executable), with MSVC 9 SP1 on Windows XP SP3, 512 MB
> RAM, Core 2 Duo 2.2 GHz (only 1 core), inside VMware Fusion 2.0,
> boost directory on VMware shared folder.
> I measured the time that it takes to compile:
> * it takes 3.5 minutes before the "...patience... ...found 488
> targets... ...updating 11 targets..." message appears
> * it then takes 20 seconds to 1 minute for the compilation to
> actually compile and link the library (depending on the exact
> configuration, i.e. with or without zlib and bzip2)
> Thanks for any suggestions on how to reduce the initial waiting time.

I'm not sure what's going on here. For me, with cold cache, do-nothing
build of the iostream library with all default variants, in SVN HEAD,
takes 22 seconds. With hot cache, it takes 2 seconds. The difference
between cold cache and hot cache cases, surely, is due to need to read
all header files to figure out dependencies. However, if you get 3.5
minutes and get it consistently, I'd suggest some misconfiguration.
Like, using shared disk may be slow. Or, VMWare has not enough memory
so the files don't end up in disk cache. Also, you're using somewhat
old Boost.Build; maybe there was some performance bug.

- Volodya

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