Re: dm-crypt and huge performance penalty

[Dmitry Nezhevenko]

On Wed, Sep 22, 2010 at 04:52:17PM -0700, Ryan Castellucci wrote:
> On Mon, Sep 20, 2010 at 3:37 PM, Dmitry Nezhevenko <dion@xxxxxxxxx> wrote:
> > Firstly I've tried to setup raid5 and then dm-crypt on top of it. After
> > discovering issue I've tried just raid5 and confirmed that mdadm itself
> > works as expected.
> >
> > And the last idea is to setup three dm-crypt partitions and then raid5 on
> > top of independently encrypted drives.
> >
> > So here are my results:
> >
> >           |  mdadm   | mdadm+dm-crypt | 3 x dm-crypt + mdadm |
> > Seq. read  | 168 Mb/s | 57 Mb/s        | 119 Mb/s             |
> > Seq. write | 80 Mb/s  | 36 Mb/s        | 64.4 Mb/s            |
> 
> dm-crypt will only use one core per device, so this is expected
> behavior (and I believe an issue that is being worked on). From these
> numbers it looks like you have a dual core or dual cpu system?
> 

Hi, Yes, The machine is home NAS with inexpensive Intel Core i3 CPU that
has two real cores and HT.
 
-- 
WBR, Dmitry
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