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Subject: Re: Intel P6 vs P7 system call performance
From: GrandMasterLee <masterlee@digitalroadkill.net>
To: Mike Hayward <hayward@loup.net>
Cc: wli@holomorphy.com, linux-kernel@vger.kernel.org
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On Fri, 2002-12-13 at 10:49, Mike Hayward wrote:
> Hi Bill,
> 
>  > On Mon, Dec 09, 2002 at 01:30:28AM -0700, Mike Hayward wrote:
>  > > Any ideas?  Not sure I want to upgrade to the P7 architecture if this
>  > > is right, since for me system calls are probably more important than
>  > > raw cpu computational power.
>  > 
>  > This is the same for me. I'm extremely uninterested in the P-IV for my
>  > own use because of this.
> 
> I've also noticed that algorithms like the recursive one I run which
> simulates solving the Tower of Hanoi problem are most likely very hard
> to do branch prediction on.  Both the code and data no doubt fit
> entirely in the L2 cache.  The AMD processor below is a much lower
> cost and significantly lower clock rate (and on a machine with only a
> 100Mhz Memory bus) than the Xeon, yet dramatically outperforms it with
> the same executable, compiled with gcc -march=i686 -O3.  Maybe with a
> better Pentium 4 optimizing compiler the P4 and Xeon could improve a
> few percent, but I doubt it'll ever see the AMD numbers.
What GCC were you using? I'd use 3.2, or 3.2.1 myself with
-march=pentium4 and -mcpu=pentium4 to see if there *is* any difference
there. On my quad P4 Xeon 1.6Ghz with 1M L3 cache, I can compile a
kernel in about 35 seconds. Mind you that's my own config, not
*everything*. On a dual athlon MP at 1.8 Ghz, I get about 5 mins or so.
Both are running with make -jx where X is the saturation value.


> Recursion Test--Tower of Hanoi
> 
> Uni  AMD XP 1800            2.4.18 kernel  46751.6 lps   (10 secs, 6 samples)
> Dual Pentium 4 Xeon 2.4Ghz  2.4.19 kernel  33661.9 lps   (10 secs, 6 samples)
> 
> - Mike
> -
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-- 
GrandMasterLee <masterlee@digitalroadkill.net>
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