Author: Charles Worthington
Date: 03:13:35 02/21/03
Go up one level in this thread
On February 21, 2003 at 05:51:51, Matt Taylor wrote: >On February 21, 2003 at 05:18:16, Charles Worthington wrote: > >>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? > >Possibly. Itanium is expensive. The CPU alone costs something like $3,000. They >are mostly used in high-end servers. Low-end Intel servers get Pentium 4 Xeons. >Supposedly Itanium-3 is also right around the corner. > >Itanium is problematic, too. Itanium does very well running IA-64 (native) >software. When you deal with Pentium 4's or Athlons or whatever, you're dealing >with IA-32 (x86) software. Itanium can run IA-32 software, but it isn't very >good at it. From the figures I have seen, it is easily eclipsed by faster >Pentium 4's or Athlons. The moral of the story is that Itanium is nice only if >you have a program compiled for IA-64 (like Crafty). > >This begs the same question be asked about Opteron, too. The difference is that >Opteron is really only an extension of x86, so x86 software is still native for >it. AMD claims that Opteron performance in x86 software will be 25% faster than >performance of the Athlon running at the same clock speed. Programs written for >x86-64 (native) will be even faster. For chess, 64-bits is also very useful. > >-Matt Thanks for the info.
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.