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Can SSE-2 Save the Pentium 4?
Siloh writes "Ace's hardware has posted a Floating-Point Compiler Performance Analysis which, in a nutshell, tests Intel's most important claim about the Pentium 4. "It does not reach its full potential with today's software, but with future software (including SSE-2 optimizations) it will outclass the competition". They test with Floating point benchmarks which have been recompiled on the latest Intel and MS compilers." Basically, another iteration of the question: Can the P4 dethrone the Athlon?
- The RAMBUS mess. They tried to leverage their chip/chipset monopoly to control the RAM market through large investments and contracts with RAMBUS. Now RAMBUS is on the brink of death and Intel has lost.
- The IA-64 disaster. It's hard to launch a new architecture, and even harder when you keep prices high and don't put enough chips in the hands of developers.
- The uniprocessor-only P4. Intel spent years perfecting SMP on their earlier processors, and for what? So that AMD could beat them to the punch, running a 1.4Ghz CPU in SMP mode. Intel also embraced the slower-but-cheaper shared memory bus architecture, which is going to kill SMP performance in comparison.
- Unwise investments. Intel has invested in several dot-coms that are dying or dead already. Intel Capital hasn't been profitable since FY 1999 because they have sunk billions into companies like VA that could never hope to turn a profit.
Intel still has potential but they will need to get their act together if they want to start competing with AMD again.-A former Intel employee
Look at the final results:
bestover2.gif
Now look at the place where the P4 shows the most improvement over the Athlon: the first data point, Flops 8, with the P4 using the Intel compiler and the Athlon using Microsoft's.
From the graph, the Pentium 4 clocks in at about 1140 flops while the Athlon gets only 900 flops.
But wait! We're forgetting something. You're running the Pentium 4 at a faster clock speed! For the love of crumbcake, normalize those values for clock speed, please!
Pentium 4: 1140 flops / 1.5 GHz = 760 flops/GHz
Athlon: 900 flops / 1.2 GHz = 750 flops/GHz
Now things are a bit more fair. Yes, with the absolute latest compiler from the maker of the processor, the Pentium 4 beats the Athlon in one of eight tests by a measly ten flops per gigahertz. With the latest compiler from some big software company, the Athlon beats the Pentium 4 in the other seven categories, hands down.
Don't believe everything you read.
It occured to me a while back that .NET while affect this immensely.
.NET compilers compile to an intermediate code level that isn't actually transformed into machine code until they are run for the first time on the target machine.
.NET IL->machine code compiler for your specific CPU and all .NET code will be totally optimised for _your_ CPU.
Consider,
This means that all you have to do to get the most out of your machine is make sure you have the
Of course, this also means that you don't need to recompile to work on any CPU that has the CLR available on it, which makes transferring to IA64 (or any other architecture) a lot easier.
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Why bother? Every iteration of processors that comes out has some special optimization that is required to run at peak performance. If you use one or the other, it gets you a marginal performance boost. Sure the P4 can do magic if you turn on this compile flag, and then disable this other. Who cares? Things are fast enough now that price should be considered the king. Why spend $100 - $200 more for a processor when all it gets you is a few more frames at 1600x1200 in Quake3. Until the P4 comes down in price (and they are making big inroads for this), the Athlon will be king.
Bryan R.
Bryan R.
The price of freedom is eternal vigilance, or $12.50 as seen on eBay.....
it's due to the fact that Pentium will flush the entire pipelines during branch-misprediction/pipelines stall. As a result Pentium III would out-perform Pentium 4 in some occasion, as the latter tends to lose more instructions when branch-misprediction rate is too high.
Rumours have it that PentiumIV will have Simultaneous Multithreading(SMT) enabled, which let's the processoor run any instruction from any thread on any unit at any time. Supposedly this feature was allready included in current processor designs but not enabled because the P6-4 is not ready for SMP yet.
AMD uses On-chip Multiprocessing(CMP) in Sledgehammer, which is basicly the sames as subdividing the resources of the cpu (registers & units) between the threads. The benefit of this technique is that the design can be kept simpeler and the clock can go faster than a similar monolithic chip with the same resources. On the other hand, a lot of resources are wasted if only one thread is operational in this setup.
Needless to say, SMT has some problems too, for example, CMP lends it self much better for branch prediction through Slipstreaming than SMT does. You can find some good reading in this previous slashpost about how intel and amd deal with multithreading on their single/multiprocessor designs. To be taken with a bit of salt of course, but very sharp.
My point is that if branch prediction in the form of Slipstreaming is implemented (and Jackson Technology seems to be that kind of SMT), the P6-4 problems with the excessive cache flushing are completely over, and SMT can take full advantage of the smaller RAMBUS latencies, easily outperforming a similar CMP setup like AMD has.
With great power comes great electricity bills.
Cheap chips rule in a soft market and AMD has demonstrated the ability to produce wicked fast at cheap prices. This would seem to be the best evidence yet that Intel has lost it's way and the bureaucracy is in need of some serious house cleaning.
Some blunders:
Tying themselves legally to Rambus
Talk of discontinuing the P3, their best mover.
Pushing the 1.13GHz P3 out the door before it was ready and suffering the consequences.
Slashing prices and subsidizing RDRAM just to move P4 product.
The P4 may have some advantages, but imagine what it would be like if AMD had rolled it out... um hm.. It would have killed the Athlon alright, assuming the Athlon were Intel's. ;-)
The truth is out there.
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All your
A feeling of having made the same mistake before: Deja Foobar
Can the P4 dethrone the Athlon
/. /    |\/| |\/| |\/| / Run, Bill!
No.
Let me explain this way: Pentium III has 6 10-stage pipelines for out-of-order superscaler execution, while Pentium 4(avoid using short-form P4 - Pentium 4 is in P6 family) has 9 20-stage pipelines.
More pipelines more stages sounds good huh? Unfortunately, in some benchmark tests Pentium III beats Pentium 4, it's due to the fact that Pentium will flush the entire pipelines during branch-misprediction/pipelines stall. As a result Pentium III would out-perform Pentium 4 in some occasion, as the latter tends to lose more instructions when branch-misprediction rate is too high.
Althon, on the other hand, only flush 1/2 pipelines on averages. They really need to fix this fundamental design glitch before they could beat Althon.
If you are very interested in this subject you can read this article. You can understand why Intel cannot giveup Pentium III in favour of the market of Pentium 4.
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I won't even get into the argument about how it might help them to Open Source the thing so that parts of the technology might be rolled into other compilers like gcc, because I just can't imagine that happening anytime soon.
Intel's working on a Linux compiler with all of the P4 goodness. Although it's in beta right now, you can bet your sweet butt your going to pay for it once the program gets out of beta. Intel may have good compilers, but they don't give 'em away
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