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Message
From: Dimitri?s Orfanos<sirtimid@g...>
Date: Mon Feb 18 14:12:46 CET 2008
Subject: [openrisc] or1ksim 's question
There are many answers for these questions.
1)If you load the linux kernel on or1ksim and on the linux kernel you
run the program then of course you have more
instructions because the simulator runs and the linux kernel.
2)The openrisc compiler produces code with many NOPs in the brand delay
slots. A better compiler (I haven't try to use the optimization switches
to say the truth , I mean to use the switch -o1 ,-o2 ,etc) could put in
the delay slots more useful code not NOPs.
3)Does the simulator stops automatically the simulation or you have to
press Ctrl-C? The "exit" function that the compiler uses by default puts
the processor (here the simulator) to infinite loop(by executing NOPs)
after the normal execution of the program. So if you want to stop the
program you press Ctrl-C ,but you are not faster than the computer so
many NOPs came again in your code.
You can check the code that was executed by seeing the file
"executed.log" that is produced from the simulator if you set the
exec_log (or exe_log , I don't remember actually) from the sim.cfg to 1.
That's all I have to say. Hope this helps.
yueng wrote:
> I change the sim.cfg , mem read and write both delay 1.
> i run jpeg decode in the or1ksim
> the result is
> 310,200,242 cycles, 171,816,396 instructions
> compare with arm7 it use only 56,000,000 cycle, and 40,000,000 instructions
>
> i remember that i read or1ksim is about 90% cycle accurate somewhere,
> same jpeg decode C code ,why or1ksim use so many instructions? and so many
> cycles.
>
>
> thank you
>
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