/bin/sh and 32-bit arithmetics [CORRECTED]

Narvi narvi at haldjas.folklore.ee
Mon Apr 21 16:39:54 PDT 2003

On Sun, 20 Apr 2003, Alex Semenyaka wrote:

>  7    5.20     6.37     3.51    22.50%     i=$(($i<<1))
>  8    5.25     6.42     3.51    22.27%     i=$(($i<<$m))
> As you can see, even for arithmetic-only script the overhead is not too big
> except with one case: shift operation. I decided to investigate is it usual
> script operation. I've went through all scripts I could find in my FreeBSD
> box. I've searched them with "locate .sh | grep '\.sh$'". There were a lot
> of them:
> $ locate .sh | grep '\.sh$' | wc -l
>     1637
> But there was no any script that uses the shift operation. Good, but not
> enough. I've take the script that uses arithmetics and do some other job,
> ttfadmin.sh from the Abiword package. I've run in 10000 times in the loop
> with both (64-bit and 32-bit) shells. As an argument it received empty
> directory so no work has been done, just run, check pars, found no files,
> exit. It takes 65.35 seconds in the first case and 65.30 second in the second
> one. So the the time that arithmetics takes during the real script execution
> is too small in comparison to total running time (obviously: arithmetics
> is in-core calculations while any script usually run some external programs
> etc, and at least I/O is involved).

Ahem - wouldn't it be easier to find out *why* the dramatic speed-down
happens and trying to combat it as opposed to trying to show the
speed-down is not releavant? There shouldn't be anything inherently that
much slower in 64 bit shifts...

> Thanks!
> 								SY, Alex

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