Merge tag 'platform-drivers-x86-v5.18-2' of git://git.kernel.org/pub/scm/linux/kernel...

[platform/kernel/linux-rpi.git] / Documentation / networking / ip-sysctl.rst

diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index 2572eec..b0024aa 100644 (file)
--- a/Documentation/networking/ip-sysctl.rst
+++ b/Documentation/networking/ip-sysctl.rst
@@ -878,6 +878,29 @@ tcp_min_tso_segs - INTEGER
 
        Default: 2
 
+tcp_tso_rtt_log - INTEGER
+       Adjustment of TSO packet sizes based on min_rtt
+
+       Starting from linux-5.18, TCP autosizing can be tweaked
+       for flows having small RTT.
+
+       Old autosizing was splitting the pacing budget to send 1024 TSO
+       per second.
+
+       tso_packet_size = sk->sk_pacing_rate / 1024;
+
+       With the new mechanism, we increase this TSO sizing using:
+
+       distance = min_rtt_usec / (2^tcp_tso_rtt_log)
+       tso_packet_size += gso_max_size >> distance;
+
+       This means that flows between very close hosts can use bigger
+       TSO packets, reducing their cpu costs.
+
+       If you want to use the old autosizing, set this sysctl to 0.
+
+       Default: 9  (2^9 = 512 usec)
+
 tcp_pacing_ss_ratio - INTEGER
        sk->sk_pacing_rate is set by TCP stack using a ratio applied
        to current rate. (current_rate = cwnd * mss / srtt)