Author: Aaron Gordon
Date: 11:17:52 03/19/03
Go up one level in this thread
On March 19, 2003 at 13:55:12, Robert Hyatt wrote: >On March 19, 2003 at 11:41:01, Aaron Gordon wrote: > >>On March 19, 2003 at 11:32:05, Robert Hyatt wrote: >> >>> >>>For those interested, the lmbench is pretty easy to run. I generally install >>>it, type >>>"make" to compile everything, then type "make results". This will ask a few >>>questions and for the specific benchmark, I usually do "HARDWARE" only as >>>opposed to all the benchmarks which measure filesystem speed, a lot of O/S stuff >>>like context switching time, network latency, etc. >>> >>>Once that finishes the first time, you can run it multiple times with the "make >>>rerun" >>>which is always advisable to see if the numbers change very slightly the second >>>run, due >>>to the program already being loaded into memory. >>> >>>Then "make see". For latency, look near the bottom. Here are the specifics for >>>my two >>>personal machines. >>> >>>1. Sony VAIO super-slim with a PIII/750mhz, and 256mb of SDRAM: >>> >>> >>>Memory latencies in nanoseconds - smaller is better >>> (WARNING - may not be correct, check graphs) >>>------------------------------------------------------------------ >>>Host OS Mhz L1 $ L2 $ Main mem Guesses >>>--------- ------------- --- ---- ---- -------- ------- >>>scrappy Linux 2.4.20 744 4.0370 9.4300 130.2 >>> >>> >>>2. Dual PIV xeon 2.8ghz, 1.0gb DDRAM, 400mhz FSB >>> >>>Memory latencies in nanoseconds - smaller is better >>> (WARNING - may not be correct, check graphs) >>>------------------------------------------------------------------ >>>Host OS Mhz L1 $ L2 $ Main mem Guesses >>>--------- ------------- --- ---- ---- -------- ------- >>>crafty Linux 2.4.20 2788 0.7180 6.5900 151.4 >>> >>> >>>Final results, my Sony with SDRAM (known for better latency) reports 130ns, >>>while my xeon with DDRAM (known for worse latency but not nearly as bad >>>as RDRAM) reports 151ns. So it seems that my 120ns number is really wrong. >>>But not in the direction everyone was claiming. :) >>> >>>If you want to download the benchmark, a search for "lmbench" should get you to >>>the right place. I'm running version 3.0. I don't know if there is a newer >>>version out. >>> >>>It is very interesting to watch it "dig" out your cache line size, TLB size, >>>etc. And it >>>also reports on cpu latency for specific instructions. IE integer bit >>>instructions take .2ns >>>on my 2.8ghz processor. That is as expected as each int op should buzz thru in >>>1/2 a clock >>>cycle, which is 1/2.8 ns per clock. >>> >>>Have fun, for those that are interested and those that "doubt". >>> >>>:) >> >>I ran the tests Hyatt. Lmbench appears to be wrong. Here is what I have so far. >>I will post more as I do the tests... These are from LMBench >> >>2.4GHz | 220fsb single-channel | CL2.5 | 66.2ns >>2.4GHz | 200fsb single-channel | CL2.5 | 73.0ns >>2.4GHz | 150fsb single-channel | CL2.5 | 102.3ns >>2.4GHz | 133fsb single-channel | CL2.5 | 114.8ns >>2.4GHz | 100fsb single-channel | CL2.0 | 123.7ns >> >>I will be testing dual-channels here in a moment. Also, I do not believe that >>LMBench is accurate. I'll do more testing with Sciencemark 2.0 for Windows. From >>the memory latency tests Matt Taylor and I agree it appears (so far) to be >>accurate. As for the LMBench test results, I'll tar.gz the results directory and >>send them to anyone that wishes to have them... > > >lmbench has _never_ been wrong in the past. It is a very well-known benchmark >with >a couple of journal papers behind it giving the details. 66.2 seems wrong, as I >mentioned, >because the Cray T90 can't break 100ns. And they are _known_ for memory speed >bandwidth and no cache. > >I'm not sure if you are greatly overclocking things or not. If so, maybe that >is what is >making the 66ns time show up. I gave the results for my dual xeon with DDR ram, >and >it certainly is nowhere near that. I'm overclocking, no doubt. At 220MHz fsb (440DDR) it was showing 66.2ns as I mentioned before. Just because I'm overclocking doesn't mean the score isn't right, it just means here in a few years when you get a system with a bus as fast as this one you'll see similar numbers. Right now you're only sticking to 100 & 133fsb (This is what P4's run at), which is very, very slow. Also the nForce2 is clearly supperior to the VIA chipsets. My KT333 at 200fsb is pulling around 94-95ns latency, at 200fsb the nForce2 is 73-74ns.
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