Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965077AbWCTQG1 (ORCPT ); Mon, 20 Mar 2006 11:06:27 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965760AbWCTQGJ (ORCPT ); Mon, 20 Mar 2006 11:06:09 -0500 Received: from kanga.kvack.org ([66.96.29.28]:26840 "EHLO kanga.kvack.org") by vger.kernel.org with ESMTP id S965165AbWCTPPR (ORCPT ); Mon, 20 Mar 2006 10:15:17 -0500 Date: Mon, 20 Mar 2006 10:09:42 -0500 From: Benjamin LaHaise To: "Michael S. Tsirkin" Cc: Lennert Buytenhek , Arjan van de Ven , "David S. Miller" , rick.jones2@hp.com, netdev@vger.kernel.org, rdreier@cisco.com, linux-kernel@vger.kernel.org, openib-general@openib.org Subject: Re: TSO and IPoIB performance degradation Message-ID: <20060320150941.GD16108@kvack.org> References: <20060320090629.GA11352@mellanox.co.il> <20060320.015500.72136710.davem@davemloft.net> <20060320102234.GV29929@mellanox.co.il> <20060320.023704.70907203.davem@davemloft.net> <20060320112753.GX29929@mellanox.co.il> <1142855223.3114.30.camel@laptopd505.fenrus.org> <20060320114933.GA3058@xi.wantstofly.org> <20060320120407.GY29929@mellanox.co.il> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060320120407.GY29929@mellanox.co.il> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1081 Lines: 22 On Mon, Mar 20, 2006 at 02:04:07PM +0200, Michael S. Tsirkin wrote: > does not stretch ACKs anymore. RFC 2581 does mention that it might be OK to > stretch ACKs "after careful consideration", and we are seeing that it helps > IP over InfiniBand, so recent Linux kernels perform worse in that respect. > > And since there does not seem to be a way to figure it out automagically when > doing this is a good idea, I proposed adding some kind of knob that will let the > user apply the consideration for us. Wouldn't it make sense to strech the ACK when the previous ACK is still in the TX queue of the device? I know that sort of behaviour was always an issue on modem links where you don't want to send out redundant ACKs. -ben -- "Time is of no importance, Mr. President, only life is important." Don't Email: . - 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/