16.01.2017 16:13, Emil Velikov пишет:
Hi Vladislav,
On 14 January 2017 at 01:50, Vladislav Egorov <[email protected]> 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.
If I understood you correctly you're saying that despite this
implementation being slower the actual total runtime remains
unchanged.
In the Attila case we even get a minimal improvement, although I'm
inclined to discard that as within the error margin.
That sounds interesting, but in all honesty I don't believe it's worth
worrying unless we have usecase(s) where the runtime difference is
noticeable.
Thanks
Emil
Sure, it's just noise, it should be slower by 1%. When using hot shader
cache it would be at most 1% difference, and at most ~2% difference on
CPUs with hardware SHA like Goldmont. I am not sure about Vulkan. But
yeah, it doesn't seem like there is something to worry about so far.
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