We at IBM Zurich Laboratory are developing a full-software iWARP stack to run within the OpenFabrics verbs framework. Today we open sourced that work to be available at http://gitorious.org/softiwarp. It consists of a kernel module (siw) and a user level library (libsiw).
The Linux kernel module implements the iWARP protocol suite (MPA/DDP/RDMAP, IETF-RFC 5044/5041/5040) completely in software. Targeted for integration with OpenFabrics kernel interfaces, it appears as a kernel module in the drivers/infiniband/hw subdirectory of the Linux kernel. siw exports the OFA RDMA verbs interface, currently useable only for user level applications. The code assumes that connection management is done via the OpenFabrics connection manager. siw runs on top of TCP kernel sockets, which are used in non-blocking mode. Current development work is done in Linux kernel version 2.6.34-rc1. libsiw implements user level access to the siw modules. It attaches with the OpenFabrics user level verbs (libibvers) and the OpenFabrics rdma connection manager (librdmacm). It is tested to run in version 1.4.1 of OpenFabrics. We belief that a software only implementation of the iWARP protocol is beneficial for the wider acceptance of the RDMA communication semantics for many reasons, including: o It allows low end systems to peer with RDMA hardware). equipped systems. This, conversely, makes the use of). RDMA hardware in loaded systems like servers a more interesting option. o It eases the migration of existing non-RDMA solutions. to the RDMA model both at application and at network stack level. o We expect that kernel clients like NSF and iSER can benefit from the existence of a software kernel RDMA stack. o While potentially not running at the full speed of an. offloaded RDMA stack, the asynchronous and one-sided communication model of RDMA itself may give the application an advantage over running on plain sockets. o The explicit communication buffer ownership management of RDMA enables the consistent implementation of user data copy avoidance techniques without hardware support. o Last not least, softiwarp offers the application programmer access to a well-documented asynchronous communication interface w/o the need to install potentially expensive hardware. Asynchronous I/O may become a viable option. We are making our work available under Dual License (BSD/Gnu) - see the Copyright statement within the source code files for details. Since the siw kernel module implements the iWARP protocol suite of the IETF, we refer to the IPR page of the IETF (http://www.ietf.org/ipr/). We explicitely declare our work as 'work-in-progress'. We make that work open source when its functionality and stability still has some limitations (see IMPLEMENTATION.txt in the infiniband/hw/softiwarp subdirectory). Some of the functional limitations are not the result of lack of time and labor: they are intentionally - we would like to discuss with the Community how to architect it the most appropriate way. We are completely open to any improvements of the code base and in fact hope to help establishing a community contributing to the improvement and completion of a software based RDMA stack. Thanks, Bernard. -- Bernard Metzler, PhD IBM Zurich Research Laboratory Säumerstrasse 4 CH-8803 Rüschlikon/Switzerland b...@zurich.ibm.com phone +41-44-7248605 -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
