This topic describes how to configure the net.ipv4.tcp_slow_start_after_idle parameter in the Linux operating system.

About the net.ipv4.tcp_slow_start_after_idle parameter

This parameter is used to control the behavior of a TCP connection when it is reactivated after being idle for a period of time. By default, the value of this parameter in the Linux kernel is 1, which means the TCP connection will immediately enter the slow start phase upon reactivation. If the value is 0, the TCP connection will not enter the slow start phase and will directly enter the congestion avoidance phase when reactivated.

Applicable scenario

Scenarios with relatively light network load

In cases of light network load, you can set this parameter to 0. This avoids every request going through the slow start process, reduces the congestion window when reactivating connections, and improves network transmission speed.

Scenarios with relatively heavy network load

In cases of heavy network load, you can set this parameter to 1 to avoid network congestion as much as possible.

Procedure

Configuration by using the proc interface

Configuration by using the net_tcp.conf file

You can use this method to temporarily modify the parameter value while the operating system is running. Each time the instance restarts, you need to configure the parameter again.

Log in to the target instance. For more information, see Logging in to Linux instances.

Execute the following command on the target Linux instance to view the current value of the tcp_slow_start_after_idle parameter.

cat /proc/sys/net/ipv4/tcp_slow_start_after_idle

Execute the following command to configure the tcp_slow_start_after_idle parameter.

echo 0 > /proc/sys/net/ipv4/tcp_slow_start_after_idle

tip

Replace 0 with the required value. Value:

0: When a TCP connection is reactivated, it will not enter the slow start phase and will directly enter the congestion avoidance phase.

1: When a TCP connection is reactivated, it will immediately enter the slow start phase.

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