[fpc-devel] FPC/Lazarus Rebuild performance

[Marco van de Voort]

In our previous episode, Jonas Maebe said:
> > I'm no expert on profiling the compiler, but if I read the various threads
> > over the years I see defensive and conflicting statements:
> > 
> > In discussions with Hans, it is said that I/O is not a factor, since after
> > one run everything is cached anyway, and then in this thread I/O is to blame
> > for a huge difference in speed.
> 
> Disk throughput doesn't really matter. Reading directory contents, getting
> file information and opening/closing files is another matter.

Good. That's what I wanted to say too. If one excludes linking, there is not
that much left. I assume the moments of timing of the FPC and Delphi compiler
of course could be different too.
 
> > The same with the fact that we use shortstring for performance in many
> > places where delphi in fact allows longer mangled names and is faster.
> 
> That's a non sequitur.

I'm not creating a complot theory here. I just want to state some facts to
avoid sidediscussion obscuring the main problem.

I'm not expecting sb will go really deep and profiling, but that doesn't
mean a somewhat correct definition of the cause of the difference would
hurt. If only for the next discussion. 

> > - Most profiling recently afaik has been done by Jonas, and thus not
> >  on Windows. Yet the delphi comparisons are on windows. 
> 
> There's a free profiler for Windows by AMD:
> http://developer.amd.com/cpu/codeanalyst/Pages/default.aspx

I'll see if I can make/enhance the wiki page about profiling the coming
days.