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

[Bela Ban (JIRA)]

Bela Ban created JGRP-1680:
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             Summary: 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: 3.5


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
* 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]
* 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

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