Author: Tom Likens
Date: 21:19:00 05/16/04
Go up one level in this thread
On May 16, 2004 at 20:57:34, Robert Hyatt wrote: >On May 16, 2004 at 19:10:30, Tom Likens wrote: > >>On May 16, 2004 at 16:54:10, Robert Hyatt wrote: >> >>>On May 16, 2004 at 15:39:18, Anthony Cozzie wrote: >>> >>>>On May 16, 2004 at 13:56:23, Tom Likens wrote: >>>> >>>>>On May 16, 2004 at 13:17:17, Anthony Cozzie wrote: >>>>> >>>>>>On May 16, 2004 at 11:10:01, Omid David Tabibi wrote: >>>>>> >>>>>>>On May 16, 2004 at 11:05:36, Anthony Cozzie wrote: >>>>>>> >>>>>>>>On May 16, 2004 at 10:14:07, K. Burcham wrote: >>>>>>>> >>>>>>>>> >>>>>>>>>Has anyone here posted using dual 248s? >>>>>>>>>wonder how 2 x 248 AMD compares to dual Xeon 3.2 with 1 meg cache running a 32 >>>>>>>>>bit commercial chess program? >>>>>>>>> >>>>>>>>>http://www.newegg.com/app/viewProductDesc.asp?description=19-103-433&depa=0 >>>>>>>>> >>>>>>>>>http://www.monarchcomputer.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=M&Product_Code=120140 >>>>>>>>> >>>>>>>>>kburcham >>>>>>>> >>>>>>>>Like Mike, I have dual 246s. Opteron is a great CPU, but the 64-bit software >>>>>>>>isn't *quite* ready, at least on linux (imo). >>>>>>> >>>>>>>Running 32 bit chess engines on that system, how much speedup do you see in >>>>>>>comparison to the fastest 32 bit dual system? >>>>>> >>>>>>I wouldn't know. I only run 64 bit linux :) It works pretty well, but there >>>>>>are definitely a few bugs left. I'd say in another 3 months my system will be >>>>>>good enough for me (new nvidia drivers, a few more kernel versions). >>>>>> >>>>>>anthony >>>>>> >>>>>>>> >>>>>>>>anthony >>>>> >>>>>Anthony, >>>>> >>>>>Are you running 64-bit SUSE or one of the Red Hat flavors? I've got an FX-51 >>>>>that I initially loaded 32-bit SUSE on (this was before SUSE supported SATA >>>>>drives right out of the box) and was pleasantly surprised at how fast the >>>>>32-bit programs ran (chess engines included). When I finally installed the >>>>>64-bit version, I was unpleasantly surprised at how *slow* the 32-bit software >>>>>ran (including and especially the various Linux engines I test against). >>>>> >>>>>I got the requiste 64-bit boost when I converted Djinn over to a true 64-bit >>>>>program but was somewhat dismayed with the 32-bit slowdown of its sparring >>>>>partners. I *could* dual-boot into a 32-bit version of Linux for testing but >>>>>frankly that offends my sensibilities and seems like a bit of a waste. >>>>> >>>>>regards, >>>>>--tom >>>> >>>>Hmm, I haven't tried. I usually test against crafty, and I compiled a version >>>>in 64-bit mode. I would have thought that 32 bit apps would run quickly because >>>>this is essentially _hardware_ emulation, but maybe not . . . . >>>> >>>>anthony >>> >>> >>>I don't see his problem. 32 bit code runs the same on a 32 bit or 64 bit >>>operating system. The opteron just doesn't get to use all its "stuff" in 32 bit >>>mode. I (and others) have done this several times and didn't see a 32 bit >>>program run slower on a 64 bit O/S... >>> >>>Not sure what is going on there... >> >>Hey Bob, >> >>Unfortunately, I can't recreate the numbers now since I got rid of the >>32-bit version of SUSE on the FX. From memory what I saw was that if I >>compiled my program under 32-bit SUSE, using the Intel 7.1 compiler and >>profile-guided optimizations, I got about 1.1M nps. So far, so good, but >>when I switched over to the 64-bit version and compiled the exact same >>program (in the same manner) I could only get a top speed of about 450k nps. >> >>I didn't really worry about it too much since I was converting the program >>over to 64-bits (which gave me all the speed back and a bit more). My >>assumption was that it was a problem with the 32-bit version of the >>libraries, but now I'm not so sure (especially, if I'm the only one seeing >>the problem). I may try a couple of experiments tonight to either verify or >>invalidate the old results. >> >>regards, >>--tom > > > >Really makes no sense. The only thing different is that the O/S has to >save/restore extra stuff when context switching (extra registers, etc). I have >not tried your experiment however. I ran Suse-64 on the quad opteron I used, >and I compiled for 32 bit or 64 bit by simply telling gcc which architecture to >produce object code for. I didn't find any difference on normal 32 bit stuff, >although Crafty ran significantly faster compiled for 64 bit, however. AMD is >putting together a demo to show the difference as they market the 64 bit >performance... You may well be right. I ran some simple tests this evening and the 32-bit executable of the program was pretty fast (700K+ nps) which was faster than I remember. This is especially significant since the changes I've been making lately have slowed the NPS down somewhat, so this number is not that far off the 64-bit version. It could be (i.e. it's likely) that I had something incorrectly configured initially. I've also patched the 64-bit version of SUSE (to the tune of about 208MB using the "9.0-PatchCD.iso" image off their website) since installing it to correct for the SATA drives. So unfortunately, at the end of the day it's probably not an apples-to-apples comparision. Anyway, my moneys on operator error ;) BTW, are you still running 64-bit SUSE or did you switch over to Red Hat? regards, --tom
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