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Date:   Thu, 20 Aug 2020 17:53:53 +1000
From:   Herbert Xu <herbert@gondor.apana.org.au>
To:     Ard Biesheuvel <ardb@kernel.org>
Cc:     Ben Greear <greearb@candelatech.com>,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        Eric Biggers <ebiggers@kernel.org>
Subject: Re: [PATCH 0/5] crypto: Implement cmac based on cbc skcipher
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On Thu, Aug 20, 2020 at 09:48:02AM +0200, Ard Biesheuvel wrote:
>
> > Or are you saying on Ben's machine cbc-aesni would have worse
> > performance vs. aes-generic?
> >
> 
> Yes, given the pathological overhead of FPU preserve/restore for every
> block of 16 bytes processed by the cbcmac wrapper.

I'm sceptical.  Do we have numbers showing this? You can get them
from tcrypt with my patch:

	https://patchwork.kernel.org/patch/11701343/

Just do

	modprobe tcrypt mode=400 alg='cmac(aes-aesni)' klen=16
	modprobe tcrypt mode=400 alg='cmac(aes-generic)' klen=16

> cmac() is not really relevant for performance, afaict. Only cbcmac()
> is used for bulk data.

Sure but it's trivial to extend my cmac patch to support cbcmac.

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