netdev - Re: Extensible hashing and RCU

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Message-ID: <20070219182642.GB10587@kvack.org>
Date:	Mon, 19 Feb 2007 13:26:42 -0500
From:	Benjamin LaHaise <bcrl@...ck.org>
To:	Eric Dumazet <dada1@...mosbay.com>
Cc:	Evgeniy Polyakov <johnpol@....mipt.ru>, akepner@....com,
	linux@...izon.com, davem@...emloft.net, netdev@...r.kernel.org
Subject: Re: Extensible hashing and RCU

On Mon, Feb 19, 2007 at 07:13:07PM +0100, Eric Dumazet wrote:
> So even with a lazy hash function, 89 % of lookups are satisfied with less 
> than 6 compares.

Which sucks, as those are typically going to be cache misses (costing many 
hundreds of cpu cycles).  Hash chains fair very poorly under DoS conditions, 
and must be removed under a heavy load.  Worst case handling is very 
important next to common case.

		-ben
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