Re: [swarm-hackers] Speed differences: Linux vs. Windows

[Marcus G. Daniels]

Steve Railsback wrote:
> Before I post these results, do you informed people have anything to 
> say about how much of the differences can be attributed to the 64-bit 
> compiler vs. differences in Swarm code vs. other differences?
> Do you think my final conclusion is reasonable?
>
> (In the past, I found negligible speed difference between 32-bit Linux 
> and Cygwin.)
I find it less than helpful to get aggregate scores that combine all 
sorts of issues into one number.
Different compilers, different versions of Swarm, different instruction 
sets, different runtimes for POSIX semantics.  About all it says is how 
much variance can be expected, but without a good model underlying that 
number, it's all guesswork what it means.  I guess it means that more 
registers are available on the 64 bit system and thus less cache pressure. 

To really understand the issues one should run all of this under 
oprofile for Linux and VTune for Windows and figure out what is 
happening on the hardware.  gprof or valgrind also work ok, but give 
less detail.

Swarm, like Linux, like Cygwin, like GCC, is all open source so at the 
end of the day, it is possible to fix anything that may be a 
bottleneck.   I think the best hope for increasing Objective C dispatch 
performance is probably LLVM Objective C compilers from Apple and link 
time optimization.

Marcus