Comment 9 for bug 246413

I can reproduce this issue with 9.10-rc (kernel version 2.6.31-14-server). I have also seen it in previous versions and on different hardware.

The slower speeds when dm-crypt is in use are obvious when testing with bonnie++ as seen below. The /data partition is an ext4-formatted 32G LVM logical volume on a multi-terabyte software RAID 10. The same volume is used in both tests - right after the first test I unmounted it, did a luksFormat, luksOpen, formatted it (with the same options) and mounted it.

The server is a quad-core Xeon and there is no reason it should be bottlenecked on this.

Without dm-crypt:

owen@fsv:~$ bonnie++ -f -n 0 -d /data
Version 1.03c ------Sequential Output------ --Sequential Input- --Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
fsv 8G 193134 25 57920 11 171750 15 605.2 1

With dm-crypt:

owen@fsv:~$ bonnie++ -f -n 0 -d /data
Version 1.03c ------Sequential Output------ --Sequential Input- --Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
fsv 8G 132252 8 31394 5 63636 6 426.7 1