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From:   "Jason A. Donenfeld" <Jason@zx2c4.com>
Date:   Thu, 17 Dec 2020 15:01:24 +0100
Message-ID: <CAHmME9qk=L1g1tMPqwSgfbzCRjp_cnxL9paPOJnRpnx8s9jTAw@mail.gmail.com>
Subject: Re: [PATCH 0/5] crypto: add NEON-optimized BLAKE2b
To:     Eric Biggers <ebiggers@kernel.org>
Cc:     Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        Ard Biesheuvel <ardb@kernel.org>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        David Sterba <dsterba@suse.com>,
        Paul Crowley <paulcrowley@google.com>
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On Thu, Dec 17, 2020 at 4:54 AM Eric Biggers <ebiggers@kernel.org> wrote:
>
> On Wed, Dec 16, 2020 at 11:32:44PM +0100, Jason A. Donenfeld wrote:
> > Hi Eric,
> >
> > On Wed, Dec 16, 2020 at 9:48 PM Eric Biggers <ebiggers@kernel.org> wrote:
> > > By the way, if people are interested in having my ARM scalar implementation of
> > > BLAKE2s in the kernel too, I can send a patchset for that too.  It just ended up
> > > being slower than BLAKE2b and SHA-1, so it wasn't as good for the use case
> > > mentioned above.  If it were to be added as "blake2s-256-arm", we'd have:
> >
> > I'd certainly be interested in this. Any rough idea how it performs
> > for pretty small messages compared to the generic implementation?
> > 100-140 byte ranges? Is the speedup about the same as for longer
> > messages because this doesn't parallelize across multiple blocks?
> >
>
> It does one block at a time, and there isn't much overhead, so yes the speedup
> on short messages should be about the same as on long messages.
>
> I did a couple quick userspace benchmarks and got (still on Cortex-A7):
>
>         100-byte messages:
>                 BLAKE2s ARM:     28.9 cpb
>                 BLAKE2s generic: 42.4 cpb
>
>         140-byte messages:
>                 BLAKE2s ARM:     29.5 cpb
>                 BLAKE2s generic: 44.0 cpb
>
> The results in the kernel may differ a bit, but probably not by much.

That's certainly a nice improvement though, and I'd very much welcome
the faster implementation.

Jason