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

[Timothy Arceri]

On Wed, 2017-01-18 at 08:30 +0000, Steven Newbury wrote:
> 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.c
> > > om
> > > > 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?

Because OpenSSL is not the only implementation used by games, leaving
this option in just leaves room for future problems. I'm all for
importing an implementation I just wanted to be sure we make a good
choice as we will likely be stuck with it for a long time.

>   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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