[dm-devel] md: dm-verity: aggregate crypto API calls

[Mike Snitzer]

On Wed, Oct 25 2017 at  4:58am -0400,
Yael Chemla <yael.chemla at foss.arm.com> wrote:

> Current implementation makes multiple crypto API calls for a single
> block, forcing underlying crypto tfm implementation to "stop & go",
> leading to under utilization of CPU (e.g. SIMD state saves) or HW
> engines. To fix it unify calls to crypto init/update/final into a digest
> call with a single sg which contains multiple buffers.
> 
> This also opens the way later on to parallelizing the work on different
> blocks.
> 
> Tested on physical Arm 32 and x86_64 and virtual ARM 64.
> 
> Performance numbers were not changed.

OK, but what about CPU utilization?  Was it reduced?

Thanks,
Mike