Re: Slowdown with randomize_va_space in 2.6.12.2

[Arjan van de Ven]

On Wed, 2005-07-06 at 18:12 -0700, Andrew Morton wrote:
> Dave Jones <davej@xxxxxxxxxx> wrote:
> >
> > On Wed, Jul 06, 2005 at 12:57:19PM -0700, David S. Miller wrote:
> >  > From: Paulo Marques <pmarques@xxxxxxxxxxxx>
> >  > Date: Wed, 06 Jul 2005 15:23:56 +0100
> >  > 
> >  > > What is weird is that most of the extra time is being accounted as 
> >  > > user-space time, but the user-space application is exactly the same in 
> >  > > both runs, only the "randomize_va_space" parameter changed.
> >  > 
> >  > It might be attributable to more cpu cache misses in userspace since
> >  > the virtual addresses of everything are changing each and every
> >  > invocation.
> > 
> > On Transmeta CPUs that probably triggers a retranslation of
> > x86->native bytecode, if it thinks it hasn't seen code at that
> > address before.
> > 
> 
> ouch.   What do we do?  Default to off?  Default to off on xmeta?

off-on-xmeta would be my preference; I'll cook up a patch for that.

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