[dm-crypt] aes-xts-plain with aes_x86_64 makes my SSD 5x slower than my encrypted HD

Yves-Alexis Perez corsac at debian.org
Sun Jul 22 21:47:32 CEST 2012

On dim., 2012-07-22 at 12:07 -0700, Marc MERLIN wrote:
> I know that SSDs are weird and all, but getting a raw device speed of
> a
> mere 23MB/sec down from 463MB/s and compared to 102MB/s for a
> similarly
> spinning drive, is a problem, is it not?
> Any suggestions would be appreciated. 

I'm using Debian sid (so still at 3.2 kernel), currently using a 256G
Samsung SSD. What I get is:

root at scapa:~# hdparm -t /dev/sda /dev/mapper/scapa_crypt 

 Timing buffered disk reads: 690 MB in  3.01 seconds = 229.47 MB/sec

 Timing buffered disk reads: 590 MB in  3.00 seconds = 196.43 MB/sec
root at scapa:~# cryptsetup status /dev/mapper/scapa_crypt 
/dev/mapper/scapa_crypt is active and is in use.
  type:    LUKS1
  cipher:  aes-xts-plain
  keysize: 256 bits
  device:  /dev/sda2
  offset:  4096 sectors
  size:    499587760 sectors
  mode:    read/write
  flags:   discards

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