BGPIO Thread Enhancements

The BGP protocol work to do Update message generation for peers in a BGP group is moved out from the main BGP thread to its own new set of pthreads, called BGP Update I/O threads. Each Update I/O thread is responsible for generating updates for one or more BGP peer groups. BGP Update threads construct updates for groups in parallel and independent of other groups that are being serviced by different update threads. This might offer significant convergence improvement in a write-heavy workload that involves advertising to many peers spread across many groups. BGP Update I/O threads can be configured independent of RIB sharding feature but are mandatory to use with RIB sharding as they help improve packing of prefixes in outbound BGP update messages and thus help improve performance. BGP update thread is disabled by default. If you configure update-threading on a routing engine, RPD creates update threads. By default, the number of update threads created is the same as the number of CPU cores on the routing engine. Update threading is only supported on a 64 bit routing protocol process (rpd). Optionally, you can specify the number-of-threads you want to create by using set update-threading <number-of-threads> statement at the [edit system processes routing bgp] hierarchy level. The range is currently 1 through 128.