I made a mistake here.  Let's back up and catch this before it gets out of hand.

>> The Linux user reported on one of their news groups that with a large Motif
>> client under X, he was able to start more instances statically linked than
>> with
>> shared libraries.  He pointed out that with HP-UX the reverse was true, and
>> indeed, when things are working properly it always should be so.
>
> That's not what I would necessarily expect.   I'd normally expect there to
> be some overhead from using shared libraries, as compared to static 
> applications, so if the test is to run lots of the same application (in which
> the text is shared anyway, and hence so are the libraries) I'd expect more
> concurrent copies to fit than running the same application, shared, many
> times (which contains exactly the same code and data, but more overhead).

Upon further review, Robert, you are correct.  The shared case will NEVER be
more efficient than the static case, when all instances are the same program.

I included that Linux posting because apparently Linux has the same problem,
and it's possible the GNU tools are the common reason.  But I remembered that
posting with only partial accuracy.  The poster said something to the effect
that "with HP-UX it was less" -- meaning the disparity between the static and
shared cases was less, not that the shared case was more efficient than static.
The issue raised there was the magnitude of the disparity between static and
shared cases, not that the disparity should be reversed.  Note that it was a
large Motif client.

Somehow people start hyperventilating whenever Linux comes up -- even me.
Must be contagious.

I designed my own test carefully to bring the clearest signal out of the data.
It shows an extrememly lopsided disparity that carries through all instances
that are run.  I used one pared down program, to control the data and isolate
the phenomenon.

I welcome your comments on my own test.


--Jim Howard  <jiho@mail.c-zone.net>
 

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E-Mail: jiho@mail.c-zone.net
Date: 17-Mar-98
Time: 18:16:34

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