Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S968425AbWLEQRo (ORCPT ); Tue, 5 Dec 2006 11:17:44 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S968424AbWLEQRo (ORCPT ); Tue, 5 Dec 2006 11:17:44 -0500 Received: from rrcs-24-153-217-226.sw.biz.rr.com ([24.153.217.226]:49288 "EHLO smtp.opengridcomputing.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S968405AbWLEQRn (ORCPT ); Tue, 5 Dec 2006 11:17:43 -0500 Subject: Re: [openib-general] [PATCH v2 04/13] Connection Manager From: Steve Wise To: Evgeniy Polyakov Cc: netdev@vger.kernel.org, Roland Dreier , linux-kernel@vger.kernel.org, openib-general@openib.org In-Reply-To: <1165335162.16087.79.camel@stevo-desktop> References: <20061202224917.27014.15424.stgit@dell3.ogc.int> <20061202224958.27014.65970.stgit@dell3.ogc.int> <20061204110825.GA26251@2ka.mipt.ru> <20061205050725.GA26033@2ka.mipt.ru> <1165330925.16087.13.camel@stevo-desktop> <20061205151905.GA18275@2ka.mipt.ru> <1165333198.16087.53.camel@stevo-desktop> <20061205155932.GA32380@2ka.mipt.ru> <1165335162.16087.79.camel@stevo-desktop> Content-Type: text/plain Date: Tue, 05 Dec 2006 10:17:43 -0600 Message-Id: <1165335463.16087.83.camel@stevo-desktop> Mime-Version: 1.0 X-Mailer: Evolution 2.4.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2582 Lines: 48 On Tue, 2006-12-05 at 10:12 -0600, Steve Wise wrote: > On Tue, 2006-12-05 at 18:59 +0300, Evgeniy Polyakov wrote: > > On Tue, Dec 05, 2006 at 09:39:58AM -0600, Steve Wise (swise@opengridcomputing.com) wrote: > > > > Phrases like "MPA-aware TCP" rises a lot of questions - briefly saying > > > > that hardware (even if it is called ethernet driver) can create and work > > > > with own TCP flows potentially modified in the way it likes which is seen > > > > in driver. Likely such flows will not be seen by upper layers like OS > > > > network stack according to hardware descriptions. > > > > > > > > Is it correct? > > > > > > > > > > I don't quite get your point about the driver aspect of this? > > > > > > The HW manages the iWARP connection including data flow. It adheres to > > > the MPA, RDDP, and RDMAP protocol specification IDs from the IETF. The > > > HW manages how data gets pushed out in the RDMA stream. The RDMA > > > Driver just requests a TCP connection and does the MPA exchange. Then > > > tells the hardware to move the connection into RDMA mode. From that > > > point on, the driver simply suffles IO work requests from the consumer > > > application to the hardware and handles asynchronous events while the > > > connection is up and running. > > > > My main concern about this is the fact, that protocol handling is > > splitted into SF and HW parts, and actually until negotiation is > > completed those parts are completely unrelated to each other, so > > requested TCP connection can leak into main stack and main stack can > > send some packets which can be considered as MPA negotiation. > > > > Ah. Data from an offloaded connection cannot leak into the main stack > nor vice-verse. We can take an active RDMA connection establishment as > an example if you want: Once the message is sent to the HW to "setup a > TCP connection from addr/port a.b to addr/port c.d", then packets on > that connection (that 4-tuple) will always be delivered to the RDMA > driver, not the native stack. If the the packet received after the > connection is setup is -not- an MPA reply (in this example), then the > connection is aborted. Once the connection is aborted. ^ the 4 tuple can then be reused for rdma or native stack tcp connections. - 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/