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Date: 8 Dec 2014 11:19:59 -0500 From: "George Spelvin" <linux@...izon.com> To: hannes@...essinduktion.org, linux@...izon.com Cc: davem@...emloft.net, dborkman@...hat.com, herbert@...dor.apana.org.au, linux-kernel@...r.kernel.org, netdev@...r.kernel.org, tgraf@...g.ch, tytso@....edu Subject: Re: Where exactly will arch_fast_hash be used >>> 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. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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