Re: Apex vs GNAT on solaris

[reason67@my-deja.com]

In article <82hnll$ahu$1@nnrp1.deja.com>,
  Robert Dewar <dewar@gnat.com> wrote:
> In article <82hiuj$74o$1@nnrp1.deja.com>,
>   reason67@my-deja.com wrote:
>
> You need to say what options you are using for both compilers.
> We have sometimes found people making the *amazing* mistake
> of compiling GNAT with -O0. Generally the appropriate options
> for benchmarking are -O2 -gnatn.

Did a gnatmake with no options. so I got gcc -c.
In apex I did the default link, which is what we were doing in
production. (Apex's results were my primary concern here, benchmarking,
if you can call it that, was an afterthought).

> The options are critical, because otherwise you may simply
> be measuring differences in choices of default options. For
> example if one compiler inlines by default, the other one
> does not, then the comparison may be meaningless.

This is true. I was actually personally concerned with the defaults that
both compilers used. I am sure I could have made GNAT run faster, and I
am sure I could have made Apex run faster. My curiousity was how they
ran "out of the box" against one another. I thought others might find it
interesting as well. This was by no stretch of the imagination anything
like a formal benchmark. I did not take network considerations into
account nor did I take system load into account. I averaged multiple
runs to general ideas of how they worked against one another.

> You also need to specify all other parameters. For instance,
> if you are running tasking, make sure you are comparing
> comparable underlying threads implementations, otherwise you
> again have apples and oranges (e.g. which of the two threads
> libraries did you use for GNAT).

Apex is running POSIX Threads. I did not install GNAT on this machine,
but my assumption, given the similarity of results is that GNAT is also
using POSIX threads. Had the timing been significantly off, I would have
checked.

Let me re-iterate one more time... These results should not ever be
consdered formal bench marks. They were simply a comparison tests I ran,
out of curiosity, with the standard Apex Posix Thread model, and the
standard GNAT 3.11 installation. Default compilation and linking options
were used.
---
Jeffrey S. Blatt


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