The Cisco-maintained v1.6 port of the usnic BTL has diverged from the
upstream trunk and v1.7 branches. This commit adjusts the trunk to more
closely match the v1.6 branch to simplify future merging and
cherry-picking.
The usnic MCA parameters also need work on this side.
Should be included in usnic v1.7.3 roll-up CMR (refs trac:3760)
This commit was SVN r29138.
The following Trac tickets were found above:
Ticket 3760 --> https://svn.open-mpi.org/trac/ompi/ticket/3760
This BTL accesses the Cisco usNIC Linux device via the Linux verbs
API via Unreliable Datagram queue pairs. A few noteworthy points:
* This BTL does most of its own fragmentation; it tells the PML that
it has a very high max_send_size (much higher than the network
MTU).
* Since UD fragments are, by definition, unreliable, the usnic BTL
handles all of its own reliability via a sliding window approach
using the opal_hotel construct and many tricks stolen from the
corpus of knowledge surrounding efficient TCP.
* There is a fun PML latency-metric based optimization for NUMA
awareness of short messages.
* Note that this is ''not'' a generic UD verbs BTL; it is specific to
the Cisco usNIC device.
This commit was SVN r28879.
