Re: Weird performance problem

[Leandro Lucarella]

Leandro Lucarella, el 14 de julio a las 20:59 me escribiste:
> Paul Smith, el 14 de julio a las 14:37 me escribiste:
> > On Wed, 2010-07-14 at 15:01 -0300, Leandro Lucarella wrote:
> > > The time was measured by several methods, including from inside the
> > > program (option -v) and using strace to trace both the program and make,
> > > and the difference are not because of make, the same program takes
> > > longer to execute itself when ran from make. Also note that the program
> > > without a change the change in the post runs equally fast inside and
> > > outside make. I can understand a program having different performances
> > > with and without a change, but I don't understand why is that difference
> > > only showing when executed inside make (and the difference is so
> > > reproducible and stable, even among different hardware).
> > 
> > Also you can try ltrace which does library calls, not just system calls.
> 
> I think I've tried that, but the output was so long I couldn't make any
> analysis from it. But maybe I should give it another try.
> 
> > I'm hard-pressed to think of any reason for this.
> 
> I'm falling back to use a script to run the tests, but it's really
> annoying me not finding the reason for this :S

Well, the odd behaviour was because Make forces the commands to use the
old Linux memory layout (indirectly triggered by making the stack
unlimited), as explained by Alberto here:
http://thread.gmane.org/gmane.comp.gnu.make.bugs/4730

I've updated the blog post for future reference too:
http://www.llucax.com.ar/blog/blog/post/-7a56a111

Thanks all for the suggestions and Alberto for finally nailing this.

-- 
Leandro Lucarella (AKA luca)                     http://llucax.com.ar/
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