> According to the OpenSM default configuration (/usr/sbin/opensm > --create-config <config>) : > > # The subnet_timeout code that will be set for all the ports > # The actual timeout is 4.096usec * 2^<subnet_timeout> > subnet_timeout 18 > > # The code of maximal time a packet can live in a switch > # The actual time is 4.096usec * 2^<packet_life_time> > # The value 0x14 disables this mechanism > packet_life_time 0x12 > > Despite the notation, they are the same values. > > It gives me: > > 4.096 * 10^-6 * 2^18 = 1.074 s > > 15 * subnet timeout / packet life time = 16.106 s ... > > This is a lot less than 98 s. > > Where does come the difference ?
The IB CM calculates the timeout as: packet lifetime * 2 + remote cm response timeout The rdma_cm has a hard coded value of 20 for the remote cm response timeout, which ends up accounting for the majority of the time... :/
