From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin LaHaise Subject: Re: Extensible hashing and RCU Date: Mon, 19 Feb 2007 13:26:42 -0500 Message-ID: <20070219182642.GB10587@kvack.org> References: <20070204074143.26312.qmail@science.horizon.com> <20070219142504.GA5626@2ka.mipt.ru> <200702191614.49666.dada1@cosmosbay.com> <200702191913.08125.dada1@cosmosbay.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Evgeniy Polyakov , akepner@sgi.com, linux@horizon.com, davem@davemloft.net, netdev@vger.kernel.org To: Eric Dumazet Return-path: Received: from kanga.kvack.org ([66.96.29.28]:58403 "EHLO kanga.kvack.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932450AbXBSS0z (ORCPT ); Mon, 19 Feb 2007 13:26:55 -0500 Content-Disposition: inline In-Reply-To: <200702191913.08125.dada1@cosmosbay.com> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 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 -- "Time is of no importance, Mr. President, only life is important." Don't Email: .