MPI RMA Ordering Semantics

Background

Some networks cannot provide end-to-end ordering. This includes both unordered networks and ordered networks used in a multi-rail context.

Hardware

Please fill in which networks provide end-to-end (memory-to-memory not NIC-to-NIC) ordering:

• Sockets

• Infiniband
  

• Myrinet
  

• Blue Gene/P - provides both ordered (static routing) and unordered (dynamic routing). DCMF channels behave like multi-rail are no ordering would be guaranteed between operations sent on different channels.
  

• Seastar
  

• Gemini
  

• Torsten's cell phone 
  

GUPS

• Apparently requires ordering.

GA/ARMCI

• Blocking operations in GA are ordered

• Nonblocking operations in GA are not ordered
  

• When the lower-level transport layer does not provide ordering, ARMCI enforces it by flushing between sequential operations. 
  

UPC/GASNet

Chapel

X10