Hemal V. Shah

High Performance Sockets and RPC over Virtual Interface (VI) Architecture

Standard user-level networking architecture such as Virtual Interface (VI) Architecture enables distributed applications to perform low overhead communication over System Area Networks (SANs). This paper describes how high-level communication paradigms like stream sockets and remote procedure call (RPC) can be efficiently built over user-level networking architectures. To evaluate performance benefits for standard client-server and multi-threaded environments, our focus is on off-the-shelf sockets and RPC interfaces and commercially available VI Architecture based SANs. The key design techniques developed in this research include credit-based flow control, decentralized user-level protocol processing, caching of pinned communication buffers, and deferred processing of completed send operations. The one-way bandwidth achieved by stream sockets over VI Architecture was 3 to 4 times better than the same achieved by running legacy protocols over the same interconnect. On the same SAN, high-performance stream sockets and RPC over VI Architecture achieve significantly better (between 2-3x) latency than conventional stream sockets and RPC over standard network protocols in Windows NT TM 4.0 environment. Furthermore, our high-performance RPC transparently improved the network performance of Distributed Component Object Model (DCOM) by a factor of 2 to 3.

A study of iSCSI extensions for RDMA (iSER)

The iSCSI protocol is the IETF standard that maps the SCSI family of application protocols onto TCP/IP enabling convergence of storage traffic on to standard TCP/IP fabrics. The ability to efficiently transfer and place the data on TCP/IP networks is crucial for this convergence of the storage traffic. The iWARP protocol suite provides Remote Direct Memory Access (RDMA) semantics over TCP/IP networks and enables efficient memory-to-memory data transfers over an IP fabric. This paper studies the design process of iSCSI Extensions for RDMA (iSER), a protocol that maps the iSCSI protocol over the iWARP protocol suite. As part of this study, this paper shows how iSER enables efficient data movement for iSCSI using generic RDMA hardware and then presents a discussion of the iWARP architectural features that were conceived during the iSER design. These features potentially enable highly efficient realizations of other I/O protocols as well.

Design and implementation of efficient communication abstractions on the virtual interface architecture: stream sockets and RPC experience

The emergence and standardization of system area networks (SANs) has provided distributed applications with a medium for high‐bandwidth, low‐latency communication. Standard user‐level networking architecture such as the Virtual Interface (VI) Architecture enables distributed applications to perform low overhead communication over SANs. The VI Architecture significantly reduces system processing overheads and provides each consumer process with a protected, directly accessible interface to the network hardware. Developing distributed applications using low‐level primitives provided by user‐level networking architecture like the VI Architecture is complex and requires significant effort.