Execution times on an ARM9 (DM368)

[bbutler@heads-up.com]

I was using Aescrypt to gather some timing data on AES. I was a little shocked at how long it took to encrypt / decrypt a file.

I compiled using Codesourcery ARM compiler with -o2 options (which cut my initial times in half)..


On a ARM 9 running 432Mhz (~500MIPS)

My results were
4 Meg file ~ 8 secs
or
500,000 bytes per sec!

Does this seem inline with the groups expectations?

[paulej]

I created a file with exactly 4000000 bytes and then I encrypted it. Here are the results on my Linux machine (Intel 32-bit):

$ time aescrypt -e -p test testfile

real 0m0.312s
user 0m0.242s
sys 0m0.028s

So, that is considerably faster than 8s. I'm not sure why it's taking so long on the ARM processor, but it might simply be that the processor is significantly slower. I really have no personal experience with that processor as a developer.

[nabila12]

Hi Mr Paulej,

I want to ask, how can i know the execution time of the encryption? should i add time string, or i just run the command?

[paulej]

The time command is what I used. That's ships with most Linux systems and can be used to measure how long a process takes.

[nabila12]

You use this command right?

$ time aescrypt -e -p test testfile

thanks so much Mr!

[paulej]

Correct

[nabila12]

i have this problem:


root@nabila2:/nabila/aescrypt-3.0.9/src# ./aescrypt -e -k test 10kb.txt
root@nabila2:/nabila/aescrypt-3.0.9/src# time aescrypt -e -k test 10kb.txt
bash: aescrypt: command not found

real 0m0.001s
user 0m0.000s
sys 0m0.000s

why this happen?

[paulej]

Since the first command you ran using "./aescrypt", I assume AES Crypt is in your current directory and not in your path. Given that, you would need to do "time ./aescrypt ...". You could install aescrypt to /usr/bin by doing "make install".

[nabila12]

it works. thanks again sir!