Author: Robert Hyatt
Date: 17:57:34 05/16/04
Go up one level in this thread
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...
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