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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Wed, 28 Jun 2023 13:10:02 -0700
Message-ID: <CAHk-=wg2-sXtHKGTsKfcMXLkvHRDiU1nQBYwB8sLo3jXfzq+cw@mail.gmail.com>
Subject: Re: [v2 PATCH 0/5] crypto: Add akcipher interface without SGs
To:     David Howells <dhowells@redhat.com>
Cc:     Ard Biesheuvel <ardb@kernel.org>,
        Eric Biggers <ebiggers@kernel.org>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Roberto Sassu <roberto.sassu@huaweicloud.com>,
        Stefan Berger <stefanb@linux.ibm.com>,
        Mimi Zohar <zohar@linux.ibm.com>, dmitry.kasatkin@gmail.com,
        Jarkko Sakkinen <jarkko@kernel.org>, keyrings@vger.kernel.org,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>
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On Wed, 28 Jun 2023 at 11:34, David Howells <dhowells@redhat.com> wrote:
>
> What about something like the Intel on-die accelerators (e.g. IAA and QAT)?  I
> think they can do async compression.

I'm sure they can. And for some made-up benchmark it might even help.
Do people use it in real life?

The *big* wins come from being able to do compression/encryption
inline, when you don't need to do double-buffering etc.

Anything else is completely broken, imnsho. Once you need to
double-buffer your IO, you've already lost the whole point.

           Linus