Messages in this thread | | | Date | 8 Dec 2014 11:19:59 -0500 | From | "George Spelvin" <> | Subject | Re: Where exactly will arch_fast_hash be used |
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>>> In case of openvswitch it shows a performance improvment. The seed >>> parameter could be used as an initial biasing of the crc32 function, but >>> in case of openvswitch it is only set to 0.
>> NACK. [...]
> Sorry for being unclear, I understood that and didn't bother patching > that '0' with a random seed exactly because of this.
And I'm sorry for delivering a long lecture on a subject you already understood perfectly well.
I'd just been thinking about it because of Herbert's comments, so it was conveniently at hand. :-)
Out of curiousity, what *were* you referring to when you talked about biasing the crc32 function? "Biasing" is a good term becuase it just applies an offset, but what do you gain from doing that?
There are nifty things one can do with the CRC32 instruction, however. A lot of ciphers these days use an ARX (add, rotate, XOR) kernel. A crc32 instruction, although linear, does some very powerful rotate & xor operations, and could replace the XOR and rotate.
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