From: Jonathan Morton <chromatix99@gmail.com>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: Dave Taht <dave.taht@gmail.com>,
codel@lists.bufferbloat.net, bloat <bloat@lists.bufferbloat.net>
Subject: Re: [Bloat] [Codel] found another good use for a queue today, possibly
Date: Tue, 27 Nov 2018 06:17:19 +0200 [thread overview]
Message-ID: <5CA2D845-508D-421C-AF38-E2B5AE0E54B2@gmail.com> (raw)
In-Reply-To: <20181126200805.1393645e@xeon-e3>
>> "polylog(n)-wise Independent Hash Function". OK, my google-foo fails
>> me: The authors use sha1, would something lighter weight suit?
> The current favorite in DPDK land seems to be Cuckoo hashing.
> It has better cache behavior than typical chaining.
That paper describes an improved variant of cuckoo hashing, using a queue to help resolve collisions with better time complexity. The proof relies on (among other things) a particular grade of hash function being used. SHA1 is described as being suitable since it offers cryptographic-level performance… We actually need two hashes with independent behaviour on the same input, one for each table.
If we were to assume table sizes up to 64K, using both halves of a good 32-bit hash might be suitable. It may be that plain old Jenkins hash would work in that context. Supplement that with a 64-entry queue with linear search (in software) or constant-time CAM search (in hardware).
- Jonathan Morton
next prev parent reply other threads:[~2018-11-27 4:17 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-27 2:17 [Bloat] " Dave Taht
2018-11-27 4:08 ` [Bloat] [Codel] " Stephen Hemminger
2018-11-27 4:17 ` Jonathan Morton [this message]
2018-11-29 4:37 ` Dave Taht
2018-11-29 17:17 ` [Bloat] " Dave Taht
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