small kernel kernel option...

[Peter Jeremy]

On 2014-Feb-26 13:48:16 -0800, John-Mark Gurney <jmg at funkthat.com> wrote:
>I'm about to commit a change to sha256 to speed it up, but the cost
>of that speed up is an increase in code/data size from just under 1k
>to almost 9k (as measured on amd64)...  this increase is from unrolling
>a loop..

Out of interest, how much of a speedup and what CPU/compiler
combinations did you test your change on?  I ask because several years
ago, I tried about 7 different SHA-256 implementations (basically, all
the C ones I could easily find in FreeBSD and ports I had installed,
as well as one I tweaked myself) across a range of CPUs and compilers.
I found that not only was there a very wide variation in speed between
implementations but that the best on one CPU often ran quite poorly on
another and unrolling loops didn't necessarily help.

-- 
Peter Jeremy
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