Re: Amulet 3 times faster than Garnet

[atwoodj@ada.CS.ORST.EDU (John Atwood)]

In article <KANDERSO.95Jun4194001@bitburg.bbn.com>,
Ken Anderson <kanderso@bitburg.bbn.com> wrote:
>In article <3qnek3$mk@Yost.com> yost@Yost.com (Dave Yost) writes:
>     * The GARNET project has left lisp behind and has gone to C++.
>       It's now 3 times faster, and more people are interested in it.
>
>This "3" is an interesting number, where does it come from?  While people
>often mention a factor of 10 difference between Lisp and C, the Lisp
>version is usually junk (sorry i only have two examples of this).  The
>analysis i've done on admitedly small programs, suggests reasonable factors
>are less than 1.5.  Garnet is a sizable chunk of code, so as an example of
>a real application, understanding the performance and other differences
>between the Lisp and C++ versions would be very valuable to us.  I can find
>the Garnet Lisp code from the Lisp Faq (ftp a.gp.cs.cmu.edu
>/usr/garnet/garnet), but where is the C++ code?

the number 3 comes from the Garnet/Amulet development team.
In the Garnet FAQ 
(http://www.cs.cmu.edu/afs/cs.cmu.edu/project/garnet/garnet/FAQ),
they answer the question, Why switch to C++, they list political & 
technical reasons. One technical reason:

* Speed: We spend 5 years and lots of effort optimizing our Lisp code,
but it was still pretty slow on "conventional" machines.  The initial
version of the C++ version, with similar functionality, appears to be
about THREE TIMES FASTER than the current Lisp version without any
tuning at all.


The C++ code is now available (Amulet alpha 0.2) at:
http://www.cs.cmu.edu/afs/cs/project/amulet/www/amulet-home.html


John
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