[Mesa-dev] [PATCH] util/hash_table: Rework the API to know about hashing

[Eric Anholt]

Timothy Arceri <t_arceri at yahoo.com.au> writes:
> On the subject of the hash table performance I spent way to much time
> looking into this recently. In the end it was taking up to much time
> benchmarking and profiling for what it was worth (at least in my test
> cases) so I've moved on for now. However for those interested here is
> what I found.
>
> Unsurprisingly most time is spent doing the hash and resolving
> collisions. For increased hash speed I implemented the _mm_crc32_u8()
> intrinsic which seemed to give a nice bump in performance and with no
> noticeable change in collisions over the FNV-1a hash.
> For better collision resolution I was looking at robin hood hashing
> which looks like a nice fit for the current table [1] but moved on
> before trying it out.

Neat.  I bet you could get measurable improvements on i965's CPU
overhead, which spends quite a bit of time hashing.
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