Red Hat SummitChapter 28. Reducing TCP performance spikes
Generating TCP timestamps can result in TCP performance spikes. The sysctl command controls the values of TCP related entries, setting the timestamps kernel parameter found at /proc/sys/net/ipv4/tcp_timestamps.
28.1. Turning off TCP timestamps
Turning off TCP timestamps can reduce TCP performance spikes and improve network latency consistency.
Prerequisites
- You have administrator privileges.
Procedure
Turn off TCP timestamps:
# sysctl -w net.ipv4.tcp_timestamps=0 net.ipv4.tcp_timestamps = 0The output shows that the value of
net.ipv4.tcp_timestampsoptions is0. That is, TCP timestamps are disabled.
28.2. Turning on TCP timestamps
Generating timestamps can cause TCP performance spikes. You can reduce TCP performance spikes by disabling TCP timestamps. If you find that generating TCP timestamps is not causing TCP performance spikes, you can enable them.
Prerequisites
- You have administrator privileges.
Procedure
Enable TCP timestamps.
# sysctl -w net.ipv4.tcp_timestamps=1 net.ipv4.tcp_timestamps = 1The output shows that the value of
net.ipv4.tcp_timestampsis1. That is, TCP timestamps are enabled.
28.3. Displaying the TCP timestamp status
You can view the status of TCP timestamp generation to verify the current configuration setting.
Prerequisites
- You have administrator privileges.
Procedure
Display the TCP timestamp generation status:
# sysctl net.ipv4.tcp_timestamps net.ipv4.tcp_timestamps = 0The value
1indicates that timestamps are being generated. The value0indicates timestamps are being not generated.
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