Peer review of AMD64/FreeBSD article

[Bill Squire]

On Fri, Mar 12, 2004 at 02:01:50PM +0100, Oliver Fromme wrote:
> Jem Matzan <valour at thejemreport.com> wrote:
>  > I've just finished writing this article comparing performance between an 
>  > Athlon64 in 32-bit and 64-bit mode using FreeBSD:
>  > 
>  > http://www.thejemreport.com/lab64/amd64vsi386.php
>  > 
>  > (this is a temporary address which will later redirect to the published 
>  > article)
>  > 
>  > I've checked it over twice for fact accuracy, but I would like other 
>  > eyes to look at it before it goes to press. I haven't spell-checked it 
>  > yet, so don't worry about that... I just want to make sure I haven't 
>  > made any factual errors.
> 
> I like the article very much.  Well done.  I also appre-
> ciate the fact that you refrained from spoiling the compa-
> rison with colorful graphics.  :-)
> 
> There are just two things which seem a bit unclear to me.
> 
> In the very first paragraph it sounds like hyperthreading
> would always be a performance win, but that's not the case.
> I've had applications that ran slightly faster when hyper-
> threading was turned off.  If I remember correctly, soft-
> ware that does many concurrent things and I/O benefits most
> from hyperthreading, while pure numbercrunching jobs run
> faster with hyperthreading switched off.  (I'm not saying
> that you should repeat all your benchmarks with hyper-
> threading off, mind you.  I just think that the remark in
> the first paragraph sounds a little bit misleading.  YMMV.)
> 
> The second point is that the gcc "benchmark" seems a bit
> unfair for me, because you're really measuring _different_
> things when compiling something for i386 and for amd64.
> The compiler is producing different code, it has to opti-
> mize differently (particularly because of the different
> register sets of the processors), so you can't really
> compare the results.  Also take into account that the amd64
> code generation engine of gcc is rather new, while the i386
> code generation is very mature.  Apart from that, I would
> rather call this "benchmark" synthetic, because nobody buys
> an Opteron to compile things all day long.  Well, except
> for the FreeBSD package building people, maybe.  :-)
> 
> In relation to that, the oggenc benchmark is certainly much
> more realistic.  It would have been nice to have some video
> decoding / encoding benchmarks, too (e.g. mplayer / menco-
> der, transcode, ffmpeg, whatever).
> 
> Well, just my 2 cents.  :-)
> 
> Regards
>    Oliver
>

Hi Oliver,

Your name seems familiar to me. Anyways, as far as benchmarks there is 
allot of 'snake oil' for salesmen out there. This is the coolest bench
mark for hardware I've ever seen. It is extremely technical and do 
understand it or limit your experiment. 
<http://www.kurims.kyoto-u.ac.jp/~ooura/fft.html> 

Good luck, (everyone -- this is fun stuff)

Bill

PS: My EUR 0,02 worth (Actually free and ALLOT of time went into getting 
this right.) You should be able to get 4M (2^22) digits of pi in about 
2:22s with a single amd64 running at 2.22GHz. :) The performance rating
of a well tuned amd64 is over 5600, the beat Intel barely gets 3000 and 
uh won't spoil the fun, but "The fastest desktop ever" (as the ads in the 
sheepish trash once read.) Will not likely beat the Intel, but I don't 
waste my time on closed source.