When the window is not fully open, your TCP stack is doing more than you think

When the window is not fully open, your TCP stack is doing more than you think2022-07-26 This post is also available in 简体中文 and 繁體中文. Over the years I've been lurking around the Linux kernel and have investigated the TCP code many times. But when recently we were working on Optimizing TCP for high WAN throughput while preserving low latency, I realized I have gaps in my knowledge about how Linux

[causeless]

"@mootastic LinuxにおけるTCPウィンドウと受信バッファの関係はどうなっているのか? を詳細に調査した報告。 (面白い要約を書こうと思ったが、新山の知識ではついていけない部分…" from https://twitter.com/i/web/status/1553575863849205760

[IGA-OS]

network

[rjj]

rmemはメタデータ含めたサイズ。溢れを防ぐためrwinはrmemの50%または64KBから始まり、メタデータのオーバーヘッドを測りつつrmem引くメタデータまで大きくなる。Coalesce/collapseしてもダメなら最悪パケット落ち。