Author: Vincent Diepeveen
Date: 08:36:51 09/29/02
Go up one level in this thread
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... DIEP's speeds at dual AMD is way faster than any dual intel version of it. Obviously DIEP is not so dependant like crafty on continuesly poking through the chipset. In general it's way harder to tune for AMD than it is for intel, no question about it, with regard to producing SMP versions of a product. However let's take SOS for example and compare speeds dual at AMD versus intel. SOS as we both know is not poking at all between the processes. Yet it gets roughly 1.8 speedup. Compare shredder, also a good speedup and AMD doing great for it. All the compares here are not so fair at all. We can benchmark crafty single cpu, but benchmarkign it > 1 cpu is simply pathetic as the parallellism is 20 years old. >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.
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