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-rw-r--r--Documentation/networking/ip-sysctl.rst23
1 files changed, 23 insertions, 0 deletions
diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index 2572eecc3e86..b0024aa7b051 100644
--- 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)