[jboss-jira] [JBoss JIRA] (JGRP-1680) RDMA based transport

RDMA based transport -------------------- Key: JGRP-1680 URL: https://issues.jboss.org/browse/JGRP-1680 Project: JGroups Issue Type: Feature Request Reporter: Bela Ban Assignee: Bela Ban Fix For: 4.1 Investigate whether an RDMA based transport makes sense. Advantages: * Speed, low latency (TCP/IP is bypassed entirely) * Low CPU usage Disadvantages: * JNI/C code ** Such a transport implementation would have to live outside of the JGroups repo ** Maintainability nightmare: the C code would also have to be ported to various OSes *** Investigate Java based libs (IBM's jVerbs) and C based libs (Apache Portable Runtime?) * High memory use, growing with cluster size: similarly to TCP, a 'group multicast' would involve N-1 sends. RDMA requires a Queue Pair (QP) for each destination. Each QP requires pinned memory (receive and send buffer), so each node would have to reserve (pin) N-1 memory buffers [1] ** OTOH, we may not use many group multicasts, e.g. with Infinispan's partial replication (DIST mode) * High cost of RDMA adapters, NICs and wiring: only a very small fraction of users would run such a transport. [1] http://www.hpcwire.com/hpcwire/2006-08-18/a_critique_of_rdma-1.html