Hi Scott,
You might want to ping your colleagues at ORNL and see how many distinct
peers they expect on upcoming XT* systems. Could be more than 64K, if
they don't do I/O forwarding (which we at ANL all hope for...).
Rob
Scott Atchley wrote:
MX provides 64 bits of match info for sends/recvs. I plan to partition
the bits as follows:
bits comment
0-3 msg_type (conn_req, conn_ack, expected, unexpected, ...?)
4-7 reserved for credits (if used)
8-15 reserved
15-31 peer id (16 bits => 65K peers)
32-63 BMI tag
The conn_req and con_ack message types allow me to do a simple handshake
to establish MX state (hostname, NIC index, endpoint index) and agree on
a version number. I'm reserving bits for credits should flow control be
necessary and another 8 bits for future use if needed. I am assuming
that 65K peers will be enough for awhile. If you think that PVFS will be
deployed on systems with more than 65K peers, I can pull from the
reserved bits to increase this id. Lastly, I will pass the BMI tag,
which is 32 bits.
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