TCP Slow Start (慢启动)

Since Linux 2.6.18.

Slow start is part of the congestion control strategy used by TCP in conjunction with other algorithms to avoid sending more data than the network is capable of forwarding, that is, to avoid causing network congestion.

Disable it:

sysctl -w net.ipv4.tcp_slow_start_after_idle=0

References

• tcp_slow_start_after_idle - tcp(7) - Debian Manpages
• RFC 2001 - TCP Slow Start, Congestion Avoidance, Fast Retransmit, and Fast Recovery Algorithms (1997.1) (Obsoleted by RFC 5681)
• RFC 2414 - Increasing TCP’s Initial Window (1998.9) (Obsoleted by RFC 3390)
• RFC 2581 - TCP Congestion Control (1999.4) (Obsoleted by RFC 5681)
• RFC 3390 - Increasing TCP’s Initial Window (2002.8)
• RFC 5681 - TCP Congestion Control (2009.9)
• RFC 1323 - TCP Extensions for High Performance (1992.5) (Obsoleted by RFC 7323)
• RFC 7323 - TCP Extensions for High Performance (2014.9)
• RFC 2861 - TCP Congestion Window Validation (2000.6) (Obsoleted by RFC 7661)
• RFC 7661 - Updating TCP to Support Rate-Limited Traffic (2015.10)
• TCP Congestion Control - Wikipedia