Re: [PATCH] i386-pda UP optimization

[Ingo Molnar]

* Andi Kleen <ak@xxxxxxx> wrote:

> On Wednesday 15 November 2006 12:27, Eric Dumazet wrote:
> > Seeing %gs prefixes used now by i386 port, I recalled seeing strange 
> > oprofile results on Opteron machines.
> > 
> > I really think %gs prefixes can be expensive in some (most ?) cases, 
> > even if the Intel/AMD docs say they are free.
> 
> They aren't free, just very cheap.

Eric's test shows a 5% slowdown. That's far from cheap.

	Ingo
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/