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Diffstat (limited to 'docs/MESHBAY_DESIGN.md')
| -rw-r--r-- | docs/MESHBAY_DESIGN.md | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/docs/MESHBAY_DESIGN.md b/docs/MESHBAY_DESIGN.md index e10209a..4db06c4 100644 --- a/docs/MESHBAY_DESIGN.md +++ b/docs/MESHBAY_DESIGN.md @@ -1531,6 +1531,26 @@ still 20, the client at a full core; 28 with the reassembly fixed; 39 with the acknowledgements, 49 by the node's own count of the transfer. An upload from the client went from 25 to 29. +**On Windows a datagram goes straight through the socket, in both directions.** +The node and its connection processes run on the ProactorEventLoop, the one that +can start ffmpeg there, and its datagram transport keeps one overlapped operation +per direction, starting the next from the completion callback of the one before, +on a later turn of the loop. A socket therefore sent one datagram per turn and +received one, and a turn lasts as long as everything else the loop does: the +other connections, the file, the hub. That is a ceiling per connection that +falls as the node gets busier, with cores to spare. With the loop otherwise busy +0.5 ms a turn: 1,928 datagrams sent a second, and 1,954 received with 87 % of +what arrived dropped by the kernel. In a node holding its connections itself, a +browser's download over eight of them ran at 9 MB/s with the node at 45 % of a +core and an SCTP round trip of 745 ms on loopback, and one of the eight sessions +was lost on the way. `proactor_udp.py` sends with a non-blocking `sendto` when +nothing is queued, and after a completed read takes whatever else the socket +holds before posting the next one; refusals and errors take the proactor's own +path. Measured on loopback on a two-core machine, 400 MB, with it: the +command-line client's download 27 to 33 MB/s, its upload 18 to 22 (23 with two +connection processes), the browser's download over eight connections 9 to 14 +before and 17 to 19 after, where the browser takes the other core. + **A session is open from the end of its handshake, and a reconnect does not shorten that.** Until connect() returns, a client sends only what the node takes before the proof — `handshake`, `handshake_response`, `keypair_bundle_fetch`, |