Re: [PATCH v2 04/10] crypto/compress: add asynchronous compression support

[Li, Weigang]

On 1/27/2016 3:41 PM, Herbert Xu wrote:
> On Tue, Jan 26, 2016 at 05:15:06PM +0900, Joonsoo Kim wrote:
> > From: Weigang Li <weigang.li@xxxxxxxxx>
> >
> > Now, asynchronous compression APIs are supported. There is no asynchronous
> > compression driver now but this APIs can be used as front-end to
> > synchronous compression algorithm. In this case, scatterlist would be
> > linearlized when needed so it would cause some overhead.
> >
> > Signed-off-by: Weigang Li <weigang.li@xxxxxxxxx>
> > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
>
> I think we should be able to use this for the synchronous case
> too, like we do with skcipher and ahash.
>
> The main difference that I can see right now is that acomp always
> allocates a context through the request object while scomp does not.
>
> This difference is entirely artificial as we could also make the
> context conditional for acomp.
>
> The reason we had the shash/ahash division is because the shash
> interface offers a direct pointer interface while ahash is SG-based.
> Otherwise ahash is just as able as shash to handle synchronous
> requests.
>
> At this point in time I don't see such a fundamental distinction
> between acomp and scomp.
>
> Cheers,
The acomp is also SG-based, while scomp only accepts flat buffer.