[sldev] Processor Optimizations (Windows)

Nicholaz Beresford nicholaz at blueflash.cc
Wed Jun 6 03:45:59 PDT 2007


James Cook wrote:
> Don't give up on compiler options!  I would happily accept a patch that 
> changed compiler optimization options, especially if there were 
> benchmark results to demonstrate the benefits.
> 
> Keep in mind though that we have to support many different processor and 
> OS combinations.  Steve may have more recent stats on what chips our 
> users are actually using, but I would be a little nervous, for example, 
> deciding to drop support for PIII chips without a solid benchmark.  We 
> don't really want to be doing multiple Windows builds internally.
> 
> I would be curious about benchmarks where SSE code generation was turned 
> on for all files.

Unfortunately I'm hardly in the position to do any proper profiling, 
much less on different hardware platforms.  As I said, this was just a
quick hack because I wanted to see if it did anything noteworthy.

What I'm wondering about is that not even "favor speed over size" was
enabled in the projects.  From what I saw as a result, the size didn't
grow to any meaningful extent, dunno if it had any impact on speed 
though, because I was turning on those features all at once.

I don't know about PIII processors,  also not how P4 optimization
would affect AMD's, but from what I can say from hands on experience
with my laptop, I doubt that your minimal requirement of a PIII/256MB
will allow for any meaningful experience, besides a SL slideshow maybe
(even running SL on a P4/1.6GHz/512MB/ATIX300 mobile was a pain and
that configuration is a long way head of of a PIII/800/256MB).

For anyone wanting to try it, the process is quite simple.  Just
mark all projects, except script_fb, go Properties and you can set
the options for all at once.

Some of them may be helpful processor independent (although agressive
inlining will make the crash dumps less readable), but I don't have
the expertise or controlled environments where I could make any
solid conclusions.  I can say, that I'm seeing higher FPSs than
before in some situations and on the same machine (even with all my 
patches applied, so it's not the patches) but that's merely a starting 
point.


Nick



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