Re: Slowdown with randomize_va_space in 2.6.12.2

[Eric Lammerts <eric@lammerts.org>]

On Thu, 7 Jul 2005, Arjan van de Ven wrote:
> On Wed, 2005-07-06 at 18:12 -0700, Andrew Morton wrote:
> > Dave Jones <davej@redhat.com> wrote:
> > > 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.

It would be nice if a fix for this could get in before 2.6.13 comes
out. What about this patch?

cheers,
Eric

--- linux-2.6.13-rc4/arch/i386/kernel/cpu/transmeta.c.orig	2005-06-17 15:48:29.000000000 -0400
+++ linux-2.6.13-rc4/arch/i386/kernel/cpu/transmeta.c	2005-07-29 20:46:54.000000000 -0400
@@ -76,6 +76,10 @@
 #define USER686 (X86_FEATURE_TSC|X86_FEATURE_CX8|X86_FEATURE_CMOV)
         if ( c->x86 == 5 && (c->x86_capability[0] & USER686) == USER686 )
 		c->x86 = 6;
+
+	/* randomize_va_space slows us down enormously;
+	   it probably triggers retranslation of x86->native bytecode */
+	randomize_va_space = 0;
 }

 static void transmeta_identify(struct cpuinfo_x86 * c)