Author: Charles Worthington
Date: 02:18:16 02/21/03
Go up one level in this thread
On February 21, 2003 at 05:04:29, Matt Taylor wrote: >On February 21, 2003 at 00:49:18, Robert Hyatt wrote: > >>On February 20, 2003 at 20:10:58, Eugene Nalimov wrote: >> >>>On February 20, 2003 at 19:09:18, Tom Kerrigan wrote: >>> >>>>It seems you know a lot more than I do about instruction latencies. How do you >>>>explain Crafty's disproportionate speedup on IA-64, then? And why would you >>>>think Crafty's performance is a good predictor of other chess programs on IA-64 >>>>when Crafty is so much different from many other programs? >>>> >>>>Of course, all we have is Hyatt's word that Crafty does well on IA-64, although >>>>he's never seen it in person, and people who have seen Crafty run on IA-64 in >>>>person seem to contradict him... >>>> >>>>-Tom >>> >>>I saw Crafty on Itanium2 in person, and results were closer to what Bob reported >>>here than to what was reported here recently. >>> >>>Thanks, >>>Eugene >> >> >>I have only seen _one_ bad Itanium2 report. I have seen _two_ good reports, >>one from Eugene, one from someone inside Intel. I have a problem with the >>Intel version because of the spec stuff I did and a NDA that is in force. >> >>However, there are other good 64bit results from the alpha 264 chip as well, >>factoring 800K from 600mhz would reach beyond 1600K at 1.25ghz, which is the >>fastest 264 I have seen. >> >>Eugene has never told me what he did to produce good results. Nor do I know >>what Intel did specifically as I was not really involved and it was just a >>"heads up" from someone there about an interesting result. Whether either >>(Eugene or Intel) tweaked the code I don't know. I specifically know that Tim >>did not for the 600mhz 264 results I posted here, he compiled that code as is >>and ran it, without even testing to see if compact-attacks was better than the >>default or not. >> >>I don't understande all the 64 bit nonsense myself. It seems pretty obvious >>that for 64 bit operations, they are going to be faster, _period_. For 32 bit >>programs, who cares? Sort of like benchmarking a non-vector program on a Cray. >>Of course it will not run very well. > >Eugene reported 3M nps for single Itanium, right? > >IIRC, my own results posted a while ago were about 1.6M nps in Crafty on a dual >1.67 GHz AthlonMP, so 800K nps at 1.67 GHz single-CPU. At 2 GHz, Athlon would be >roughly 1M nps. Itanium is faster then by a factor of 3 at half the clock speed. >Half the clock speed means it has equivalent theoretical IPS (6x1 GHz vs. 3x2 >GHz). Assuming -all- ops were 64-bit and therefore Crafty derived a speedup of >2, that does not account for the additional gain which is rather significant. > >Yes, Crafty will run faster on a 64-bit machine, but will it run that much >faster? Unless I have made some error, I don't see how the 64-bit machine word >could solely explain the speed gains on Itanium. I don't really know where the >extra speed came from. Maybe it's from the cache. Maybe Itanium comes much >closer to 6 IPC than Athlon does to 3 IPC. There are any number of explanations, >but I don't know because I have no idea how efficient IA-64 compilers are. > >-Matt Matt, might this processor also be another option to the Opteron that I may want to consider?
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