Re: difference between jari's and hvr's package

[Steve Weigand <weigand@texas.net>]

On Wed, Mar 06, 2002 at 11:14:59PM +0200, Jari Ruusu wrote:
> 
> Tested on 2.4.18 kernel, Pentium-2 300 MHz, ST34342A IDE disk
> 
> Implementation  Cipher        Total CPU cycles spent in system mode
> --------------  ------        -------------------------------------
> cryptoapi       AES-128       54 %
> loop-AES        AES-128       36 %
> cryptoapi       serpent-128   81 %
> loop-AES        serpent-128   78 %
> 
> All above implementations used the disk at maximum data transfer rate
> supported by the disk, so megabytes/sec rate was same for all ciphers on
> unloaded test box.
> 
> Serpent implementations used same cipher source code. Cryptoapi overhead on
> loop encryption seems to be few percent of CPU cycles.


That's strange.  So AES does much more in user-mode than serpent does?
So that's why serpent's run time is dominated by system-mode cpu
cycles whereas AES is not?  Why is that?  What part is running in
user-mode out of curiosity?

And why is there such a large discrepancy between cryptoapi's AES
CPU time and loop-AES's AES CPU time?  Context switching?

 - Steve Weigand
   (weigand@texas.net) Austin, Texas USA  http://weigand.home.texas.net

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Linux-crypto:  cryptography in and on the Linux system
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