Re: [RFC v3 1/1] eCryptfs: Use the ablkcipher crypto API

[Colin Ian King <colin.king@canonical.com>]

On 09/04/13 20:07, Tyler Hicks wrote:
> Make the switch from the blkcipher kernel crypto interface to the
> ablkcipher interface.
>
> encrypt_scatterlist() and decrypt_scatterlist() now use the ablkcipher
> interface but, from the eCryptfs standpoint, still treat the crypto
> operation as a synchronous operation. They submit the async request and
> then wait until the operation is finished before they return. Most of
> the changes are contained inside those two functions.
>
> Despite waiting for the completion of the crypto operation, the
> ablkcipher interface provides performance increases in most cases when
> used on AES-NI capable hardware. However, sequential I/O with one or two
> threads on slow storage media does exhibit a sizeable decrease in
> performance.
>

With the testing I've run with the ablkcipher patch I observe a 
noticeable performance win with fast media such as SSD or tmpfs and a 
slight improvement with fast 7200 rpm HDDs. With slower HDDs, I don't 
see any negative performance impact with ablkcipher.  Exercised on a 
recent AES-NI capable Intel 4 core server with 7200 rpm HDD and Intel 
330 SSD and also with a Intel i3-2350M Lenovo X220i laptop with a 5400 
rpm HDD and Intel 330 SSD.

I have also given this patch considerable amount of soak testing 
overnight with continuous parallel kernel builds while also running the 
eCryptfs tests without any issues.

As it stands, I am happy with v3 of this patch.