Re: [dm-crypt] LUKS & TrueCrypt - Speed Test

[Milan Broz <mbroz@redhat.com>]

On 07/28/2011 01:18 AM, Jorge Fábregas wrote:

> - Between the above tests, I shut down the machine (to flush filesystem
> cache).

echo 3 > /proc/sys/vm/drop_caches

does the same in more controlled way

> - my system kernel: 2.6.35.13-92.fc14.i686

Can you use something more recent? There were huge changes.
The same for userspace.

BTW do you know that TC7 uses dm-crypt as backend? So with the same
mode and alignemnt you should get the same results
(except chained ciphers in TC).

> As you can see, there's almost a 4 minute difference.  I was expecting
> LUKS to be faster (as dm-crypt is a kernel module) and TrueCrypt runs
> mainly in user space isn't it?  Do you think the cipher operation modes
> (XTS vs CBC) played a role in this difference? Have any of you performed
> a similar test?

Perhaps because you tested different modes... Use the same mode
in cryptsetup

cryptstup luksFormat -c aes-xts-plain64 -s 512 ... 

I would really wonder if speed differs, TC7 uses dmsetup to configure
dm-crypt mapping on Linux :-) It uses userspace (and FUSE)  only for old
containers and some magic for hidden container.

Milan