[dm-crypt] Encrypting with larger packet size

Dinesh Garg dinesh.garg at gmail.com
Tue Jan 22 07:04:09 CET 2013


I want to use hardware based crypto engine which would provide better
encryption/decryption throughput when packet sizes are bigger. If we invoke
hardware based crypto engine for every 512 bytes, there is so much time
spent in setting up cipher context in that throughput becomes very less.

When I ran IOZONE benchmark on device with and without encryption,
performance is upto 70% slower. This data is based on SW based crypto
engine.

Thats why I was thinking if I can contribute to dm-crypt where it can
accept larger packet sizes, it would be great for hardware based crypto
engine solution.

HW based crypto engine outperforms the SW based when packet size reaches
8K.


On Mon, Jan 21, 2013 at 9:42 PM, Arno Wagner <arno at wagner.name> wrote:

> Why would you want to do this? There doe snot seem to be any
> good reason...
>
> Arno
>
> On Mon, Jan 21, 2013 at 08:18:50PM -0800, Dinesh Garg wrote:
> > Hi,
> >
> > Currently dm-crypt encrypts the block device using sector size. Is it
> > possible to change this to use larger sizes such as 8K or 16K or larger?
> If
> > not possible currently, what would it take to make that possible i..e
>  what
> > are the problems that we need to fix?
> >
> > Is it DM layer that restricts us to use larger sizes or file system due
> to
> > its block size?
> >
> > I have one more question: How does a read operation ends up at calling
> > dm-crypt api?
> >
> > Thanks,
> > DG
>
> > _______________________________________________
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> > dm-crypt at saout.de
> > http://www.saout.de/mailman/listinfo/dm-crypt
>
>
> --
> Arno Wagner,     Dr. sc. techn., Dipl. Inform.,    Email: arno at wagner.name
> GnuPG: ID: CB5D9718  FP: 12D6 C03B 1B30 33BB 13CF  B774 E35C 5FA1 CB5D 9718
> ----
> One of the painful things about our time is that those who feel certainty
> are stupid, and those with any imagination and understanding are filled
> with doubt and indecision. -- Bertrand Russell
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