Author: Robert Hyatt
Date: 08:32:05 03/19/03
Go up one level in this thread
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".
:)
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