Author: Robert Hyatt
Date: 20:43:26 09/29/02
Go up one level in this thread
On September 29, 2002 at 00:33:30, Aaron Gordon wrote: >On September 28, 2002 at 12:39:05, Robert Hyatt wrote: > >>On September 28, 2002 at 04:28:02, Aaron Gordon wrote: >> >>>On September 27, 2002 at 23:42:03, Robert Hyatt wrote: >>> >>>>I didn't run the SMP tests for AMD, I don't have a one here and have no plans >>>>to get one. I posted a chart of data others provided. I don't even remember >>>>which position we used now. All that was significant was that all the speedup >>>>numbers (raw nps, not parallel search times) were in the 1.4-1.5 range with >>>>AMD, and 1.8 and above for the intel boxes... >>>> >>>>I personally believe it highlights a memory bottleneck... >>> >>>I don't think it's fair for you to find the slowest possible binary for the AMD >>>and some IntelC5 binary and then claim that the speedup is slow. I don't think >>>it's fair either if someone takes a slow binary for a P4 and compares it to a >>>fast binary for an AMD cpu. >> >>I'm not doing that. But you are missing the point as we are not comparing >>speeds between AMD and Intel. I run _any_ executable on AMD using one >>cpu, then the same using two, and compute the NPS speedup. I do the same for >>Intel. It won't matter whether the executable is fast or slow, as I am not >>comparing nps between intel and AMD. I am comparing the NPS speedup from 1-2 >>cpus on AMD against the NPS speedup from 1-2 cpus in Intel... >> >>Fast or low executables won't make any difference in the _ratio_ I was looking >>at. Slow executable on AMD will still see a proportional speedup. Because the >>raw NPS is not important, the ration of 1 cpu to 2 cpus is all that counts >>here.. And AMD has problems... Not major problems, but problems nontheless... >> >> >> >> >>> >>>You seem to conveniently forget the benchmarks I've done and other people here >>>have done. Take a look at my latest graph of crafty results: >>>http://speedycpu.dyndns.org/crafty/craftybench4.jpg >>>Note: the P4 2.76GHz is an overclocked 1.8A northwood at 153.5fsb(614MHz RDRAM). >> >>I'm not forgetting _anything_. Benchmark nps does not matter whatsoever to >>_this_ discussion. It is _only_ the ratio of 2 cpu time to 1 cpu time for >>each specific processor. It shows that it is harder to run two cpus wide open >>on AMD than it is on Intel. >> >> >>> >>>Now, the SMP binaries I have are able to produce a 1.7x speedup in the >>>benchmark. You claim the P4's get 1.8x, thats fine. Take the P4-2.76's result >>>(1,120,011 nps) and multiply it by 1.8. You get 2,016,019.8 nps. Not too shabby, >>>right? Well.. take the 1.86Ghz XP and multiply it's nps by 1.7 and you get >>>2,035,330.1. Still faster. Now, if you're saying, "Well yadda yadda is >>>overclocked and etc etc". Yeah, and even faster things will be released here >>>shortly. I can guarantee the P4-2.76 w/ 614MHz RDRAM would be as fast or a hair >>>faster than a standard P4-2.8. The AthlonXP at 1.86 would be more around a 2300+ >>>if such a thing existed. >> >> >>Again, you are missing the point. I didn't say AMD was _slower_ than Intel >>anywhere. I simply said their two cpu machine does _not_ scale as well as >>the Intel duals. Nothing more, nothing less. That remains an easy to prove >>fact... >> >> >> >>> >>>Moving on to the future.. P4-3GHz will soon be released as well as the 2800+ >>>(being announced on October 1st). Lets do some rough guessing. If a P4 gets >>>1,120,011 nps @ 2.76 it should get about 1,217,403 nps at 3GHz and thats >>>probably still having the RDRAM clocked to insanity. Take the 2.52GHz AthlonXP @ >>>1,578,197. At 2133MHz (AthlonXP 2600+) it should do about 1,335,831 nps. Again >>>do 1,335,831 * 1.7 and 1,217,403 * 1.8 and you get: >>>2,270,912.7 nps for the dual XP 2600+ (2.13ghz) >>>2,191,325.4 nps for the dual P4-3GHz. >> >>Maybe or maybe not. But it _still_ doesn't change the fact that the dual AMD >>is less efficient (should optimally be 2x faster than a single) than a dual >>]intel... >> >> >> >>> >>>Since Crafty is pretty linear you know these numbers are very close to the >>>actual results. So far from what I've seen Pentium4's need an entire GHz more >>>and twice the L2 cache just to come close. This is what I call a $500 keychain. > >I'm just pointing out that you say it gets a 1.4x speedup when infact with a >decent binary it gets 1.7x. What is the 1.8x speedup for the P4's good for if >the AMD cpus are faster anyway? It all comes down to the AMD chips being faster >in a dual configuration even with the Intel SMP systems pulling 1.8x. You could >have some special configuration or something that pulls a perfectly linear >speedup but if the cpus are slow it won't matter, the faster dual with a >slightly lower speedup would be better. > 1. I didn't see anyone post _any_ 1.7x number for AMD when I asked for them a week or two back. 2. I don't see how the binary is going to affect this at all. You should get the same ratio of single to dual whether you use a fully-optimized binary or one with no optimizing at all. Since the dual speed is relative to the single cpu version, the base NPS is unimportant. >I'm not saying that Intel cpus are super slow or they get a slower speedup than >the Athlons BUT, I am saying that even with the small speedup advantage over the >SMP Athlon systems it still isn't enough to beat it in raw NPS. If AMD decided >to make a slow CPU that got a 1.95x speedup.. would you use that instead? I >somehow doubt it.. but you are doing the same thing here with the Intel setups. > No, actually I am using a quad intel machine. Where are the quad AMDs? Why do you think there are none? Think about "scaling"... >With two 2400+'s costing $199 each and a superb SMP board (Iwill MPX2) costing >under $200 a dual 2GHz AthlonXP setup is pretty cheap compared to some SMP >P4-2.8GHz setup. I don't know what sort of overclocking options the P4-SMP board >would have (if any) but the dual 2400+ should hit 2.3GHz easily. Non-overclocked >it would still beat a 2xP4-2.8 at less than half the cost. :) > >SMP P4 2.8GHz, board = $350 (at least), two cpus ($480 each) = $960 >Total: $1310 >SMP XP 2.0GHz, board = $195, two cpus ($199 each) = $398 >Total: $593 > >SMP P4-2.8GHz estimated nps: 2,016,019 >SMP XP-2.0GHz estimated nps: 2,129,313 > >XP-2.0GHz is 5.62% faster and $717 cheaper. > >You could build another computer for what you saved *AND* still be faster >than the expensive P4 system. Except that I can buy a quad or 8-way P4 system, but not an AMD. And now they get left in the dust... Not cheap of course.. But not even doable with AMD.
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