Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964878AbWEaJDN (ORCPT ); Wed, 31 May 2006 05:03:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964877AbWEaJDN (ORCPT ); Wed, 31 May 2006 05:03:13 -0400 Received: from relay.2ka.mipt.ru ([194.85.82.65]:41162 "EHLO 2ka.mipt.ru") by vger.kernel.org with ESMTP id S964873AbWEaJDM (ORCPT ); Wed, 31 May 2006 05:03:12 -0400 Date: Wed, 31 May 2006 13:03:02 +0400 From: Evgeniy Polyakov To: David Miller , draghuram@rocketmail.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org Subject: Re: Question about tcp hash function tcp_hashfn() Message-ID: <20060531090301.GA26782@2ka.mipt.ru> References: <20060530235525.A30563@openss7.org> <20060531.001027.60486156.davem@davemloft.net> <20060531014540.A1319@openss7.org> <20060531.004953.91760903.davem@davemloft.net> <20060531020009.A1868@openss7.org> Mime-Version: 1.0 Content-Type: text/plain; charset=koi8-r Content-Disposition: inline In-Reply-To: <20060531020009.A1868@openss7.org> User-Agent: Mutt/1.5.9i X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-1.7.5 (2ka.mipt.ru [0.0.0.0]); Wed, 31 May 2006 13:03:03 +0400 (MSD) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1045 Lines: 28 On Wed, May 31, 2006 at 02:00:09AM -0600, Brian F. G. Bidulock (bidulock@openss7.org) wrote: > > For sure and there are plans afoot to move over to > > dynamic table sizing and the Jenkins hash function. > > Yes, that could be far more efficient. In theory practice and theory are the same, but in practice they are different. Current simple XOR hash used in socket selection code is just bloody good! Jenkins hash unfortunately has _significant_ artefacts which were found in netchannel [1] hash selection analysis [2]. And Jenkins hash is far too slower. 1. Netchannel. http://tservice.net.ru/~s0mbre/old/?section=projects&item=netchannel 2. Compared Jenkins hash with XOR hash used in TCP socket selection code. http://tservice.net.ru/~s0mbre/blog/2006/05/14#2006_05_14 -- Evgeniy Polyakov - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/