Re: [PATCH] poly1305: generic C can be faster on chips with slow unaligned access

From	Sandy Harris <sandyinchina@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] poly1305: generic C can be faster on chips with slow unaligned access
Date	2016-11-02 21:50 +0100
Message-ID	<szaDT-2J2-1@gated-at.bofh.it> (permalink)
References	<sz7Zn-Wx-11@gated-at.bofh.it> <szaaR-2yB-15@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Wed, Nov 2, 2016 at 4:09 PM, Herbert Xu <herbert@gondor.apana.org.au> wrote:

> On Wed, Nov 02, 2016 at 06:58:10PM +0100, Jason A. Donenfeld wrote:
>> On MIPS chips commonly found in inexpensive routers, this makes a big
>> difference in performance.
>>
>> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
>
> Can you give some numbers please? What about other architectures
> that your patch impacts?

In general it is not always clear that using whatever hardware crypto
is available is a good idea. Not all such hardware is fast, some CPUs
are, some CPUs have hardware for AES, and even if the hardware is
faster than the CPU, the context switch overheads may exceed the
advantage.

Ideally the patch development or acceptance process would be
testing this, but I think it might be difficult to reach that ideal.

The exception is a hardware RNG; that should always be used unless
it is clearly awful. It cannot do harm, speed is not much of an issue,
and it solves the hardest problem in the random(4) driver, making
sure of correct initialisation before any use.

Thread

[PATCH] poly1305: generic C can be faster on chips with slow unaligned access "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-11-02 19:00 +0100
  Re: [PATCH] poly1305: generic C can be faster on chips with slow  unaligned access Herbert Xu <herbert@gondor.apana.org.au> - 2016-11-02 21:20 +0100
    Re: [PATCH] poly1305: generic C can be faster on chips with slow  unaligned access Sandy Harris <sandyinchina@gmail.com> - 2016-11-02 21:50 +0100
    Re: [PATCH] poly1305: generic C can be faster on chips with slow  unaligned access "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-11-02 22:10 +0100
      Re: [PATCH] poly1305: generic C can be faster on chips with slow  unaligned access Herbert Xu <herbert@gondor.apana.org.au> - 2016-11-02 22:10 +0100
        Re: [PATCH] poly1305: generic C can be faster on chips with slow  unaligned access "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-11-02 22:30 +0100
          Re: [PATCH] poly1305: generic C can be faster on chips with slow  unaligned access Herbert Xu <herbert@gondor.apana.org.au> - 2016-11-02 22:30 +0100
            Re: [PATCH] poly1305: generic C can be faster on chips with slow  unaligned access "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-11-02 23:10 +0100
              Re: [PATCH] poly1305: generic C can be faster on chips with slow  unaligned access Herbert Xu <herbert@gondor.apana.org.au> - 2016-11-03 01:50 +0100
                Re: [PATCH] poly1305: generic C can be faster on chips with slow  unaligned access "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-11-03 08:30 +0100
                Re: [PATCH] poly1305: generic C can be faster on chips with slow  unaligned access David Miller <davem@davemloft.net> - 2016-11-03 18:10 +0100
                Re: [PATCH] poly1305: generic C can be faster on chips with slow  unaligned access "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-11-03 23:30 +0100
                Re: [PATCH] poly1305: generic C can be faster on chips with slow  unaligned access Eric Biggers <ebiggers@google.com> - 2016-11-04 18:40 +0100
                Re: [PATCH] poly1305: generic C can be faster on chips with slow  unaligned access "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-11-07 19:10 +0100
                Re: [PATCH] poly1305: generic C can be faster on chips with slow  unaligned access "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-11-07 19:30 +0100
                Re: [PATCH] poly1305: generic C can be faster on chips with slow  unaligned access Eric Biggers <ebiggers@google.com> - 2016-11-07 19:40 +0100
                Re: [PATCH] poly1305: generic C can be faster on chips with slow  unaligned access "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-11-07 20:10 +0100
                Re: [PATCH] poly1305: generic C can be faster on chips with slow  unaligned access Eric Biggers <ebiggers@google.com> - 2016-11-07 20:30 +0100
                Re: [PATCH] poly1305: generic C can be faster on chips with slow  unaligned access "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-11-07 20:50 +0100
  [PATCH v2] poly1305: generic C can be faster on chips with slow unaligned access "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-11-07 20:20 +0100
    [PATCH v3] poly1305: generic C can be faster on chips with slow unaligned access "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-11-07 20:50 +0100
    [PATCH v4] poly1305: generic C can be faster on chips with slow unaligned access "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-11-07 21:00 +0100
      Re: [PATCH v4] poly1305: generic C can be faster on chips with slow  unaligned access Eric Biggers <ebiggers@google.com> - 2016-11-07 21:50 +0100
      Re: [PATCH v4] poly1305: generic C can be faster on chips with slow  unaligned access Martin Willi <martin@strongswan.org> - 2016-11-08 09:10 +0100
        Re: [PATCH v4] poly1305: generic C can be faster on chips with slow  unaligned access Eric Biggers <ebiggers@google.com> - 2016-11-08 18:30 +0100

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