Re: [PATCH] DM-CRYPT: Scale to multiple CPUs

Tomasz Chmielewski
2010-05-31T18:57:15Z

Milan Broz wrote:

> On 05/31/2010 06:04 PM, Andi Kleen wrote:
>> DM-CRYPT: Scale to multiple CPUs
>>
>> Currently dm-crypt does all encryption work per dmcrypt mapping in a
>> single workqueue. This does not scale well when multiple CPUs
>> are submitting IO at a high rate. The single CPU running the single
>> thread cannot keep up with the encryption and encrypted IO performance
>> tanks.
>
> This is true only if encryption run on the CPU synchronously.
>
> (Usually it is high speed SSD or dm-crypt above striped RAID where
> underlying device throughput is higher than CPU encryption speed.)

Quite common to hit on a netbook/laptop with encrypted root these days,
where storage can be relatively fast when compared to the speed of one
of the cores of the (usually) multicore CPU.

--
Tomasz Chmielewski