Enlarging Linux UDP buffer size

One of the most common causes of UDP data gram lost on Linux is an undersized receive buffer on the Linux socket. How to enlarge Linux UDP buffer size?

On Linux, you can change the UDP buffer size (e.g. to 26214400) by (as root):

sysctl -w net.core.rmem_max=26214400

The default buffer size on Linux is 131071.

You can also make it permanent by adding this line to /etc/sysctl.conf:


What is net.core.rmem_max?

rmem_max controls the maximum socket buffer size that can be allocated. The maximum sizes for socket buffers declared via the SO_SNDBUF and SO_RCVBUF mechanisms are limited by the values in the /proc/sys/net/core/rmem_max and /proc/sys/net/core/wmem_max files.

“rmem_max the maximum receive socket buffer size in bytes” – ref.

Not that it can also affect TCP‘s performance beside of UDP’s.

Eric Ma

Eric is a systems guy. Eric is interested in building high-performance and scalable distributed systems and related technologies. The views or opinions expressed here are solely Eric's own and do not necessarily represent those of any third parties.


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