The tech committee would like to announce a new accepted talk.

Jon Maloy will give a talk on the new TIPC ring neighbor monitoring.

Details are
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Title: Overlapping Ring Neighbor Monitoring Algorithm in 1000-node Clusters

In Linux 4.7 we introduced a fundamentally new neighbor monitoring
algorithm to TIPC. This algorithm has several advantages:

- It scales better than full mesh monitoring. CPU load increases by
  sqrt(N) instead of by N, network load by sqrt(N)*N instead of N^2.

- Swift neighbor failure discovery is guaranteed even in the presence
  of a partitioned network, contrary to what regular ring supervision
  algorithms can do.

- It has short and deterministic failure discovery times, contrary
  to the Gossip algorithm.

The algorithm is completely distributed, self-adaptive and employs no
centralized or coordinated state. It scales up to at least 1000 nodes
with a failure discovery time in the order of 1 second. We believe this
algorithm should be useful in large container or VM clusters, as well
as in native systems.

A brief summary of the algorithm:

- Each node sorts all its N known neighbors into a circular list. The
  algorithm for this is the same on all nodes.

- The node identifies the next sqrt(N) nodes downstream from itself in
  the list, -its "monitoring domain", and supervises those actively.

- It distributes a record describing its monitoring domain to all the
  neighbors. A new record is distributed when there is a change, e.g.,
  a lost node, in the local domain.

- When a node outside a node's local domain is lost, it relies on updates
  from the sqrt(N) nodes actively monitoring that node for discovering
  the loss.

- In order to handle failures causing a partitioned network, each node
  also selects a set of nodes outside its own domain to monitor actively.
  Those nodes are selected so that no node is more than two active
  supervision hops away. There will be sqrt(n) such nodes. This
  guarantees that a node will discover loss of indirectly monitored
  nodes in a remote partition within a period marginally longer than
  the detection time for actively monitored nodes.

- Each node will immediately re-calculate a new optimal monitoring
  configuration upon any change in the cluster.
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cheers,
jamal
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