Encrypted volume read/write too fast...

[creaker]

Hi!
I encrypted one of the partitions following this wiki page: http://wiki.gentoo.org/wiki/Dm-crypt
Once got device mounted, I decided to test read/write performance. I copied a 4Gb file and paste it into container. Unexpectedly file was copied too fast: operation took 45 secs. It's a 91Mb/sec. Afaik, it shouldn't be so fast. The read/write speed for encrypted partition should be 20-70 Mb/sec according to this benchmark: http://blog.wpkg.org/2009/04/23/cipher-benchmark-for-dm-crypt-luks/
Encrypted partition status:

[Hu]

I think you are using a 5+ year old benchmark to analyze the performance of hardware you did not describe. If you have a much faster system, good hardware offload, or used more caching than was used in the benchmark, then comparing your results to theirs is meaningless. I see that the blog post was edited a year after its posting to note that DM-Crypt became SMP aware, which could affect performance.

[HeissFuss]

Are you measuring the time it takes to copy and sync to disk, or just copy? When the copy completes, that just means it's in RAM disk buffer, prior to encryption/disk write.

Also, AES with any modern Intel processes does AES-NI CPU offload of AES, which is very fast. You can benchmark the actual CPU throughput (minus disk) with 'cryptsetup benchmark'

[creaker]

@ Hu
I saw that the date is 2009. The HDD used for linked above benchmark even faster than mine: 105Mb/s vs 100Mb/s.
Though, you are right, multithreading might be enabled by default since 2009. I wasn't aware of it.

[creaker]