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Date:   Wed, 2 Dec 2020 09:16:28 +1100
From:   Herbert Xu <herbert@gondor.apana.org.au>
To:     Ard Biesheuvel <ardb@kernel.org>
Cc:     Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        Ben Greear <greearb@candelatech.com>,
        Steve deRosier <derosier@cal-sierra.com>
Subject: Re: [PATCH v2] crypto: aesni - add ccm(aes) algorithm implementation
Message-ID: <20201201221628.GA32130@gondor.apana.org.au>
References: <20201201194556.5220-1-ardb@kernel.org>
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On Tue, Dec 01, 2020 at 11:12:32PM +0100, Ard Biesheuvel wrote:
>
> What do you mean by just one direction? Ben just confirmed a

The TX direction generally executes in process context, which
would benefit from an accelerated sync implementation.  The RX
side on the other hand is always in softirq context.

> substantial speedup for his use case, which requires the use of
> software encryption even on hardware that could support doing it in
> hardware, and that software encryption currently only supports the
> synchronous interface.

The problem is that the degradation would come at the worst time,
when the system is loaded.  IOW when you get an interrupt during
your TX path and get RX traffic that's when you'll take the fallback
path.

Cheers,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt