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Subject: Re: [Boost-build] Major engine changes
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2011-11-29 21:49:27


On 11/29/2011 05:57 PM, Rene Rivera wrote:
> On 11/29/2011 6:02 PM, Steven Watanabe wrote:
>> I've just committed a major rewrite of the
>> jam interpreter. So, far, I'm seeing a 2x speed
> Using which metric?

Elapsed wall-clock time.

> And which test case?

bjam -n -d0 in $BOOST_ROOT/status
on Linux. The initial state was
what this command leaves behind,
so repeated calls would run the
same updating actions.

> Did memory usage change also?
> (This is one area where I know we are slow as a consequence of the
> enormous mem use.)

Apparently so, although I wasn't particularly
trying to reduce memory usage.

On Windows compiling with MSVC 10.0 Express,
with the same command:

before: 231 seconds, 790 MB
after: 150 seconds, 665 MB

In $BOOST_ROOT with bjam --build-type=complete -n -d0:

before: 38 seconds, 110 MB
after: 27 seconds, 88 MB

>> Here's a summary of all the behavior changes
>> that I am aware of. Some of these are just
>> bug fixes, but I'm including them for completeness.
> OK.. But I really would like to see a summary of the performance changes.

Most of the speed up comes from replacing the
insane variable expansion algorithm.

In Christ,
Steven Watanabe

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