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From: Michael van der Westhuizen (Michael.vanderWesthuizen_at_[hidden])
Date: 2003-09-22 04:36:18

I've found it a lot faster on HP-UX, Tru64 and SunOS (all with gcc).

The machines in question don't have a shortage of RAM though (a
few spare GB of RAM could make all the difference in the world!),
and disk I/O is not really a bottleneck.

Given a reasonable amount of RAM one could probably look at the
average amount of RAM taken by compiling a translation unit and
adjust -jN to free RAM / that number. To if one has 512MB you
could probably use -j2 happily (even with the more deeply nested

On a slightly different topic: I do have access to some higher-end
hardware - if anybody wants me to test specific code for 64bit and
little endian vs. big endian portability, just let me know.


-----Original Message-----
From: David Abrahams [mailto:dave_at_[hidden]]
Sent: 21 September 2003 03:44
To: boost_at_[hidden]
Subject: [boost] Re: Speeding up testing

Beman Dawes <bdawes_at_[hidden]> writes:

> At 03:23 PM 9/20/2003, David Abrahams wrote:
> >
> >For those people running the Boost regression tests, I suggest you try
> >invoking bjam with -jN to do some of the build jobs in parallel. Even
> >on uniprocessor systems it seems to help quite a bit to compile/link
> >while some other process is waiting for the disk, and on
> >multiprocessors I imagine it would be even better. I am using -j4 on
> >my uniprocessor laptop now, for example.
> I tried -jN a while ago when I got a hyperthreading CPU, and it did
> seem to improve build speeds as long as GCC wasn't one of the
> compilers.
> I didn't spend a lot of time diagnosing the problem with GCC, but what
> seemed to have been happening was that GCC used so much memory that
> running multiple compiles chewed up all the machine's RAM and
> more. That kills file caching, which in turn kills performance.
> Did you try with GCC?

Yep, but I wasn't measuring. It just seemed faster.

Dave Abrahams
Boost Consulting
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