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

Marc MERLIN marc at merlins.org
Mon Jul 23 19:54:23 CEST 2012


On Mon, Jul 23, 2012 at 06:19:10PM +0200, Yves-Alexis Perez wrote:
> > I'll try rebuilding a non preempt kernel just in case.
> 
> Maybe try with Debian kernel first? It's just an apt-get install away
> and will give you a setup identical as mine.

I have a custom initramfs, it was easier to compile a new kernel than to try
and get the debian one to boot my system :)

But for reference, what kernel package are you using?

On Mon, Jul 23, 2012 at 07:27:47PM +0200, André Gall wrote:
> I remember a test which I conducted after I received my Intel SDD 510 
> 120 GB about 1 year ago. I don't remember all the details, but the 
> essence was that write speed decreased dramatically if the write process 
> wasn't aligned.
 
> I did:
> dd if=/dev/zero of=/dev/sda bs=4k
> I got around 400 Mb/sec, which was expected. But when I did:
> 
> dd if=/dev/zero of=/dev/sda bs=5k
> I got only around 40 Mb/sec

Yes, write alignment and write amplification are definitely issues on SSDs,
but note how I was only doing read tests :)

See
http://www.void.gr/kargig/blog/2012/01/11/linux-ssd-partition-alignment-tips/

Cheers,
Marc
-- 
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems ....
                                      .... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/  


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