Re: Intel P6 vs P7 system call performance

[Vojtech Pavlik]

On Thu, Dec 12, 2002 at 03:36:46PM -0500, Mark Mielke wrote:
> On Thu, Dec 12, 2002 at 10:42:56AM +0100, Terje Eggestad wrote:
> > On ons, 2002-12-11 at 19:50, H. Peter Anvin wrote:
> > > Terje Eggestad wrote:
> > > > PS:  rdtsc on P4 is also painfully slow!!!
> > > Now that's just braindead...
> > It takes about 11 cycles on athlon, 34 on PII, and a whooping 84 on P4.
> > For a simple op like that, even 11 is a lot... Really makes you wonder.
> 
> Some of this discussion is a little bit unfair. My understanding of what
> Intel has done with the P4, is create an architecture that allows for
> higher clock rates. Sure the P4 might take 84, vs PII 34, but how many
> PII 2.4 Ghz machines have you ever seen on the market?
> 
> Certainly, some of their decisions seem to be a little odd on the surface.
> 
> That doesn't mean the situation is black and white.

Assume a 1GHz P-III. 34 clocks @ 1GHz = 34 ns. 84 clocks @ 2.4 GHz = 35 ns.
That's actually slower. Fortunately the P4 isn't this bad on all
instructions.

-- 
Vojtech Pavlik
SuSE Labs