[Mesa-dev] [PATCH] util: import sha1 implementation from OpenBSD

[Steven Newbury]

On Mon, 2017-01-16 at 16:52 +0300, Vladislav Egorov wrote:
> 
> 16.01.2017 16:13, Emil Velikov пишет:
> > Hi Vladislav,
> > 
> > On 14 January 2017 at 01:50, Vladislav Egorov <vegorov180 at gmail.com
> > > wrote:
> > > 14.01.2017 01:45, Timothy Arceri пишет:
> > > > I'm asking for a chance to test before we jump in, its probably
> > > > not a
> > > > big deal and I may even still be able to reduce my use of
> > > > hashing but
> > > > it would be nice to be given a few days to test and even
> > > > explore
> > > > alternatives before jumping on this implementation.
> > > 
> > > A very quick and very dirty simple benchmark. I took shader-cache 
> > > from
> > > github, branch shader-cache39. Then I've applied my preprocessor
> > > patch on
> > > top (because shader-cache still uses preprocessor even if the
> > > shader is
> > > cached and it was painful to see preprocessor taking more than
> > > half of the
> > > whole time). Then I've compiled it with openssl and with the
> > > Emil's patch.
> > > Full run on shader-db (300Mb+ of shaders) with shader-cache
> > > warmed up. It
> > > takes 78s, spends in libcrypto 0.27%. With OpenBSD SHA1 it runs
> > > approximately the same time, spends 0.53% in SHA1Transform() and
> > > other SHA1*
> > > functions. Subtest - 46Mb of shaders from Total War: Attila -
> > > 3.10s (for
> > > some reason, the cache works much faster on smaller subsets than
> > > on full
> > > shader-db). 1.08% were spent in libcrypto, 1.04% in
> > > sha1_block_data_order_avx2(). With OpenBSD 3.07s - 2.27% in
> > > SHA1Transform()
> > > and other SHA1* functions.
> > > 
> > 
> > Did you mean "shader-db" with the "shader-cache" references above ?
> > I
> > cannot find any projects with the latter name on github.
> 
> I meant Timothy's github: https://github.com/tarceri/Mesa
> 
> > > Overall not that significant in context of shader-cache, but as
> > > expected, on
> > > Haswell it's twice slower than OpenSSL's AVX2 implementation.
> > 

Why not leave in a build time option for whichever is the fastest (non-
OpenSSL) external SHA1 implementation but default or fallback to
whatever gets pulled into the tree?  That way integrators/distributions
get to decide if they want to support the extra dependency and it
removes almost all the variations and extra support machinery.
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