[DISPATCH-1975] TCP adaptor sends only 512-byte packets over network

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.15.0
• Fix Version/s: 1.17.0, 1.16.1
• Component/s: Protocol Adaptors
• Assignee: Charles E. Rolke
• Reporter: Charles E. Rolke
• Created: 22/Feb/21 15:34
• Updated: 23/Aug/21 15:01
• Resolved: 11/Aug/21 12:05

Description

Setup

Running some iperf3 tests with a single router over localhost interfaces and looking at wireshark traces.

Observation

• router is receiving from the iperf3 client in 64k-byte packets
• router is sending to the iperf3 server in 512-byte packets

  Discussion

This is perfectly understandable if the iperf3 server connection is setting NO_DELAY=true.

This is really bad for performance in general. Network performance loves bigger data frames on the wire.

Single-router performance would be improved if dispatch coalesced the 512-byte buffers into something bigger before handing them off to proton. The idea is for TCP to share the HTTP2 raw buffering scheme that uses 16k-byte proton raw buffers.