Rayhaan JaufeerallyandClaude Fable 5.1
381eabd886
The exporter built each UPDATE as a message: the attributes of the route's set, parsed from the table, were cloned, had the next hop added, were sorted, and were handed to the session, which encoded them to the wire with the rest of the message. For a table whose attribute sets each cover a few routes that is an encoding of the same octets for nearly every route, and a copy of the message's bytes on the way to the writer besides. A profile of a production router taking the other router's table with ADD-PATH had the exporters at 55% of the CPU time, their dressing of routes at 23%, and memcpy at 12%. A route's attributes are now encoded once for a session, when it is first dressed for it, and kept with where in the octets a NEXT_HOP or an MP_REACH_NLRI belongs so that the attributes stay in order of type code. An UPDATE is then its header, the encoded octets with the next hop or the MP_REACH_NLRI spliced in, and the prefixes: written straight into a buffer that goes to the session as it is, and from the session to the writer without a copy. The session's queue takes either a message or an encoded UPDATE; an encoded one for a session that is no longer established is dropped, as the exporter made it for the session as it was. What is kept for a route, now a few hundred octets instead of a kilobyte, lets twice as many be kept. The exporter's maps hash with foldhash instead of SipHash, and the parser context for an UPDATE is made once a flush instead of once an UPDATE. Testing: a new test encodes a thousand routes with each of the forms an UPDATE takes (IPv4 with the next hop in its own attribute, IPv6 in MP_REACH_NLRI, with and without path identifiers, to two-octet and four-octet AS speakers, over several messages) both ways and checks the octets are the same byte for byte; the message-building form is kept for the test. The exporter tests decode what the session is handed. The server tests, the integration tests, the kernel tests and every lab phase pass. On the mesh benchmark in the Linux VM, three rounds each alternating with the previous commit, the two routers' exchange of 7.4 million routes takes 20.6 s of CPU time instead of 25.4 s (-19%) over 9.0 s of wall-clock time instead of 11.1 s, and the larger of the two tables is across in 7.1 s instead of 9.3 s. The smaller table's time varies too much from run to run (5-8 s) for a difference to be read from it. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
BGP Packet
This crate implements parsers and serialisers for the Border Gateway Protocol wire format.
It is used by the daemon in bin/bgp, and tested with property tests
(tests/properties.rs) and fuzz targets (fuzz/).