Re: [PATCH crypto-next v2 1/3] crypto: poly1305 - add new 32 and 64-bit generic versions

Ard Biesheuvel
2019-12-12T14:26:37Z

On Thu, 12 Dec 2019 at 14:47, Jason A. Donenfeld <Jason@zx2c4.com> wrote:
>
> On Thu, Dec 12, 2019 at 2:08 PM Jason A. Donenfeld <Jason@zx2c4.com> wrote:
> >
> > Hi Martin,
> >
> > On Thu, Dec 12, 2019 at 1:03 PM Martin Willi <martin@strongswan.org> wrote:
> > > Can you provide some numbers to testify that? In my tests, the 32-bit
> > > version gives me exact the same results.
> >
> > On 32-bit, if you only call update() once, then the results are the
> > same. However, as soon as you call it more than once, this new version
> > has increasing gains. Other than that, they should behave pretty much
> > identically.
>
> Oh, you asked for numbers. I just fired up an Armada 370/XP and am
> seeing a 8% increase in performance on calls to the update function.

It would help if we could get some actual numbers. I usually try to
capture the performance delta for a small set of block sizes that are
significant for the use case at hand, e.g., like so [0], and also
include blocksizes that are not 2^n. If the change improves the
general case without causing any significant regressions elsewhere, I
don't think we need to continue this debate.

[0] https://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git/commit/?id=11031c0d7d6e9bca0df233a8acfd6708d2b89470