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From:   Ard Biesheuvel <ardb@kernel.org>
Date:   Tue, 1 Dec 2020 07:32:46 +0100
Message-ID: <CAMj1kXGt_sjyBH1veEEEizHjUMWEkuTUicxmhbLjQXnJ9LXGpw@mail.gmail.com>
Subject: Re: [PATCH] crypto: aesni - add ccm(aes) algorithm implementation
To:     Ben Greear <greearb@candelatech.com>
Cc:     Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Steve deRosier <derosier@cal-sierra.com>
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On Mon, 30 Nov 2020 at 23:48, Ben Greear <greearb@candelatech.com> wrote:
>
> On 11/29/20 10:20 AM, Ard Biesheuvel wrote:
> > From: Steve deRosier <ardb@kernel.org>
> >
> > Add ccm(aes) implementation from linux-wireless mailing list (see
> > http://permalink.gmane.org/gmane.linux.kernel.wireless.general/126679).
> >
> > This eliminates FPU context store/restore overhead existing in more
> > general ccm_base(ctr(aes-aesni),aes-aesni) case in MAC calculation.
> >
> > Suggested-by: Ben Greear <greearb@candelatech.com>
> > Co-developed-by: Steve deRosier <derosier@cal-sierra.com>
> > Signed-off-by: Steve deRosier <derosier@cal-sierra.com>
> > Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> > ---
> > Ben,
> >
> > This is almost a rewrite of the original patch, switching to the new
> > skcipher API, using the existing SIMD helper, and drop numerous unrelated
> > changes. The basic approach is almost identical, though, so I expect this
> > to perform on par or perhaps slightly faster than the original.
> >
> > Could you please confirm with some numbers?
>
> I tried this on my apu2 platform, here is perf top during a TCP download using
> rx-sw-crypt (ie, the aesni cpu decrypt path):
>
>    18.77%  [kernel]                            [k] acpi_idle_enter
>    14.68%  [kernel]                            [k] kernel_fpu_begin
>     4.45%  [kernel]                            [k] __crypto_xor
>     3.46%  [kernel]                            [k] _aesni_enc1
>
> Total throughput is 127Mbps or so.  This is with your patch applied to 5.8.0+
> kernel (it applied clean with 'git am')
>
> Is there a good way to verify at runtime that I've properly applied your patch?
>
> On my 5.4 kernel with the old version of the patch installed, I see 253Mbps throughput,
> and perf-top shows:
>
>    13.33%  [kernel]                            [k] acpi_idle_do_entry
>     9.21%  [kernel]                            [k] _aesni_enc1
>     4.49%  [unknown]                           [.] 0x00007fbc3f00adb6
>     4.34%  [unknown]                           [.] 0x00007fbc3f00adba
>     3.85%  [kernel]                            [k] memcpy
>
>
> So, new patch is not working that well for me...
>

That is odd. The net number of invocations of kernel_fpu_begin()
should be the same, so I cannot explain why they suddenly take more
time. I am starting to think that this is a different issue
altogether.

One thing that you could try is dropping the '.cra_alignmask' line as
we don't actually need it, but I am skeptical that this is the cause
of this.