Network Congestion Working Group

Current Situation
	▪	Sometimes communication runtime tool API (like PMPI / QMPI / XMPI) does not provide enough information
	⁃	We may need more detail information from the network hardware
	▪	Each network vendor has their own hardware counters and API for monitoring 

Goals
	▪	Find out if there is any communication bottleneck ? 
	If that is the case: Where ?

	▪	Proposal: common API to access info from network fabrics
	PAPI has some support but it's vendor specific (as far as we know)
		It depends on the host adapter 

Wish List
	▪	Possible required information for communication diagnostics:
	Latency, the topology of the network, NIC (HCA), switches
	The route of the message
	The status of all the network switches/controllers
	…. etc (need to be defined)

	▪	Hardware counter should be accessible from user space
	Caution: need to be careful for the security

Action Plan
Need to define what information we need from the network vendor
Need to dig more information on network specification
	spec from IB volume 1
	spec from Cray gemini
Read papers on how to use network hardware counter
	Sandia Lab paper on Cray gemini hardware counters
Participation in hardware counter for network/communication
	CORAL network hardware counters efforts (Swen & Rashawn)