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Date: Mon, 1 Dec 2014 16:30:09 -0800
Message-ID: <CAJBj3vd83Vgfxsfitbz0vVma-jPWb22nj=PC-kigxnipV=BrKA@mail.gmail.com>
Subject: Re: [RFC PATCH] Btrfs: add sha256 checksum option
From: John Williams <jwilliams4200@gmail.com>
To: Alex Elsayed <eternaleye@gmail.com>
Cc: Btrfs BTRFS <linux-btrfs@vger.kernel.org>
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On Mon, Dec 1, 2014 at 4:15 PM, Alex Elsayed <eternaleye@gmail.com> wrote:
> There's a thing called the transitive property. When CRC32 is faster than
> SpookyHash and CityHash (while admittedly weaker), and SHA-1 on SPARC is
> faster than CRC32, there are comparisons that can be made.

And yet you applied the transitive property with poor assumptions and
in a convoluted way to come up with an incorrect conclusion.


> It's that the flat assertion that "CityHash/SpookyHash/etc is always faster"
> is _unwarranted_, as hardware acceleration _has a huge effect_.

Actually, the assertion is true and backed up by evidence that I
cited. I'm not sure why you think hardware acceleration only helps
SHA-1 and does not help CityHash or SpookyHash.