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parameter tuning tcp_conn_request_max

Frequent Advisor

parameter tuning tcp_conn_request_max


I need to tune the parameter tcp_conn_request_max=8192.

I have checked nddconf file above line is not availble and how to make it.

Honored Contributor

Re: parameter tuning tcp_conn_request_max

Hi ,

There are already so many threads on this.
You can put an entry if it is not there.
If you want to set temporary, you can use

ndd -set command

From Rick's document


Maximum number of outstanding inbound connection requests.
[1, - ] Default: 20 connections

This is also known as the maximum depth of the "listen queue." The
actual maximum for any given TCP endpoint in the LISTEN state will be
the MINIMUM of tcp_conn_request_max and the value the application
passed-in to the listen() socket call.

For this parameter to take effect for a given application, it must be
set BEFORE said application makes its call to listen(). So, if you use
ndd to set this value after the application has started, it will have
no effect unless you can get the application to recreate its LISTEN

You can see if tcp_conn_request_max MIGHT be too small by looking at
the output of either "netstat -s" or "netstat -p tcp" and looking for
the line displaying the number of connection requests dropped due to
full queue. If the number of drops is zero, the value of
tcp_conn_request_max is fine. If the value is non-zero, either
tcp_conn_request_max is too small, or the values the applications are
using in their calls to listen() are too small.

Setting this value higher has no particular downside. Editing
/etc/rc.config.d/nddconf to set this value to say 1024 is probably not
a bad idea for any "internet server" system.

"UNIX is basically a simple operating system, but you have to be a genius to understand the simplicity" - Dennis Ritchie
Laurent Menase
Honored Contributor

Re: parameter tuning tcp_conn_request_max

in fact you can add any ndd configuration to nddconf.
just add

in fact the 0 is the index of the table so if you already have configurations in your ndd conf, you must use index+1 for your cnfiguration