Author: Aaron Gordon
Date: 08:41:01 03/19/03
Go up one level in this thread
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...
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