Author: Hristo
Date: 23:22:06 07/24/03
Go up one level in this thread
On July 25, 2003 at 00:51:13, Tom Kerrigan wrote: >On July 24, 2003 at 23:14:52, Hristo wrote: > >>On July 24, 2003 at 20:43:14, Dann Corbit wrote: >> >>>On July 24, 2003 at 17:27:55, Vincent Lejeune wrote: >>> >>>>http://www.apple.com/quicktime/qtv/wwdc03/ -> click "watch now" -> go to >>>>1:40:30; You will see Power Mac G5 perform a little more than 2 times faster >>>>than a dual Xeon 3.06 !!! Live run, screens side by side, with 4 or 5 different >>>>applications. >>> >>>Figures don't lie. >>>But liars will figure. >>> >>>The shame from Apple's current misinformation campaign won't go away until they >>>start telling the truth. >>> >>>A little distortion is not unexpected. But they are simply telling absurd tall >>>tales. >> >>Dan, >>if the applications being compared were using Altivec optimized code on the Mac >>and were dependent heavily on this part of the code, then the Mac being 2 times >>faster is easy to imagine. >> >>What they, Apple, don't tell "you" as a consumer is that only a few Applications >>can gain execution speed from Altivec stuff ... and when it does happen you can >>often feel that the P4 are slow, which is not the case for the general purpose >>Applications. >> >>Why do you think Apple is not telling the truth? More precisely, what is it that >>they are dishonest about, in relation to the above mentioned demo? >> >>Regards, >>Hristo > > >* The IBM guy was bragging about their 0.13um process, saying how great it is, >saying that only IBM and Apple could deliver it... Hmmm... Intel has been >selling 0.13um P4s for a year and a half and AMD has been selling 0.13um Athlons >for, what, a year? Intel is going to be selling 0.09um processors not long after >Apple starts shipping the 0.13um processors that only they are awesome enough to >deliver, sure. > >* Steve says the 3.0GHz P4 was the fastest they could buy, but actually they >could have bought a 3.2GHz P4. > >* Steve says the G5 is the world's first 64 bit desktop processor. The Opteron >has been out for months now. If you want to argue that the Opteron is a >workstation/server processor and not a "dektop" processor, then why are they >comparing the G5 to a Xeon? > All of this is not related to the question of "Why did the applications demoed performed so much faster on the Macs?". I see no point to argue about any of these presentation related inaccuracies ... :) >* Of course there's the fiasco with Apple's SPEC scores being _way_ lower than >officially submitted SPEC scores. > Another on of those "inaccuracies" ... I don't understand why they used this for anything other than PR time. I simply don't remember the last time I picked a system based purely or even partially on the SPEC performance, do you? >* For the Photoshop and music demos, it seemed like the PC was stalling out for >some reason. Is it because it didn't have as much memory? Is it because they >were taking advantage of some problem with a memory allocator and it was >thrashing? Maybe a virus scanner was running. > and maybe the people from Adobe, Wolfram Research and Lux... all agreed to lie about their experiences with the performance of those systems. :-) It is possible that the G5 Macs will perform better than the 3.06 Xeons which were used for the demo, without the Xeons being crippled in any way. Don't you think? >BTW, you mention Altivec. What makes you think IBM's implementation of Altivec >is any better than Intel's implementation of SSE2? Where to start on this one? :) SSE2 provides a fine optimization path for the P4 class CPUs. However, to compare the _implementation_ of the SSE2 and Altivec is somewhat misleading and confusing. Both of these technologies provide SIMD instructions and very wide registers (128 bits), but the similarities end right around _here_ ... :-) SSE2 has 8 registers, and shuts off the scalar part of the CPU and has a bunch of weird dependencies. Arranging SSE2 code that keeps pumping without stalls and bubbles is tough, much tougher than using the Altivec with 32-128 bit registers and a fully functional scalar unit while addressing the Altivec. Even if we take all of these differences away and I had to choose between the two I would still pick the Altivec, based on its instruction set alone. IBMs implementation of Altivec might not be better than Motorola, but that is a different conversation, eh? ;-) However, the performance benefit from SSE2 coupled with extremely high clock makes the P4 one mean-machine. Further more ICC does, in some cases, optimize using the SSE2 which is certainly a great help for the programmer and a complete nightmare for a PR person trying to compare CPU performance without being able to use to special features of his own CPU. I would imagine the faces people will make when/if Apple manages to tweak gcc to do auto vectorization on the said SPEC tests. That is a very big _IF_ and a very long __when__. :) IMO > >One also has to ask what in the world Jobs is doing up there, oh so happy about >having a 2GHz processor, when MHz don't matter. ;) > Here I totally agree! The itanium FPU, even though is clocked much lower, still outperforms every other 64-bit CPU. IIRC Cheers, Hristo >-Tom
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