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

Milan Broz mbroz at redhat.com
Mon Jul 23 23:31:28 CEST 2012


On 07/23/2012 07:51 PM, Marc MERLIN wrote:
> On Mon, Jul 23, 2012 at 07:15:24PM +0200, Milan Broz wrote:
>>> Mmmh, I have one possible thing. I have a preempt kernel. Could that be it?
>>> http://marc.merlins.org/tmp/config-3.4.4-amd64-preempt.txt
>>
>> Can you send me your kernel .config then? Preempt should not be problem.
>> Which kernel version? which architecture? Any additional patches over
>> mainline code?
> 
> I just sent you my config, it was in the URL above :)
> No patches, kernel 3.4.4 from kernel.org, see above.

Ehm... sorry, I completely missed that. Thanks.

> Really?
> I used fdisk -H32 -S32 /dev/sda as recomended on
> http://www.void.gr/kargig/blog/2012/01/11/linux-ssd-partition-alignment-tips/

Do not use -H32 -S32. It is crazy and obsolete way how to align it...
Someone is wrong in the internet seems http://xkcd.com/386/ ;-)

Disk driver should set topology parameters which fdisk uses. But for your
case all is set to 512 bytes...

Whatever, there was a bug in fdisk, fixed now thanks to your report :)
https://github.com/karelzak/util-linux/commit/c0175e6185ac81843cbad33cbea75abd033f0e66

> Thanks for the other suggestions. Hopefully we'll nail this somehow :)

Well, please try some default distro compiled kernel if you can reproduce it there.

Milan


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