mirror of
https://github.com/coredns/coredns.git
synced 2025-08-06 22:37:03 +02:00
93 lines
2.6 KiB
Groff
93 lines
2.6 KiB
Groff
.\" Generated by Mmark Markdown Processer - mmark.miek.nl
|
|
.TH "COREDNS-MULTISOCKET" 7 "May 2025" "CoreDNS" "CoreDNS Plugins"
|
|
|
|
.SH "NAME"
|
|
.PP
|
|
\fImultisocket\fP - allows to start multiple servers that will listen on one port.
|
|
|
|
.SH "DESCRIPTION"
|
|
.PP
|
|
With \fImultisocket\fP, you can define the number of servers that will listen on the same port. The SO_REUSEPORT socket
|
|
option allows to open multiple listening sockets at the same address and port. In this case, kernel distributes incoming
|
|
connections between sockets.
|
|
|
|
.PP
|
|
Enabling this option allows to start multiple servers, which increases the throughput of CoreDNS in environments with a
|
|
large number of CPU cores.
|
|
|
|
.SH "SYNTAX"
|
|
.PP
|
|
.RS
|
|
|
|
.nf
|
|
multisocket [NUM\_SOCKETS]
|
|
|
|
.fi
|
|
.RE
|
|
|
|
.IP \(bu 4
|
|
\fBNUM_SOCKETS\fP - the number of servers that will listen on one port. Default value is equal to GOMAXPROCS.
|
|
|
|
|
|
.SH "EXAMPLES"
|
|
.PP
|
|
Start 5 TCP/UDP servers on the same port.
|
|
|
|
.PP
|
|
.RS
|
|
|
|
.nf
|
|
\&. {
|
|
multisocket 5
|
|
forward . /etc/resolv.conf
|
|
}
|
|
|
|
.fi
|
|
.RE
|
|
|
|
.PP
|
|
Do not define \fB\fCNUM_SOCKETS\fR, in this case it will take a value equal to GOMAXPROCS.
|
|
|
|
.PP
|
|
.RS
|
|
|
|
.nf
|
|
\&. {
|
|
multisocket
|
|
forward . /etc/resolv.conf
|
|
}
|
|
|
|
.fi
|
|
.RE
|
|
|
|
.SH "RECOMMENDATIONS"
|
|
.PP
|
|
The tests of the \fB\fCmultisocket\fR plugin, which were conducted for \fB\fCNUM_SOCKETS\fR from 1 to 10, did not reveal any side
|
|
effects or performance degradation.
|
|
|
|
.PP
|
|
This means that the \fB\fCmultisocket\fR plugin can be used with a default value that is equal to GOMAXPROCS.
|
|
|
|
.PP
|
|
However, to achieve the best results, it is recommended to consider the specific environment and plugins used in
|
|
CoreDNS. To determine the optimal configuration, it is advisable to conduct performance tests with different
|
|
\fB\fCNUM_SOCKETS\fR, measuring Queries Per Second (QPS) and system load.
|
|
|
|
.PP
|
|
If conducting such tests is difficult, follow these recommendations:
|
|
1. Determine the maximum CPU consumption of CoreDNS server without \fB\fCmultisocket\fR plugin. Estimate how much CPU CoreDNS
|
|
actually consumes in specific environment under maximum load.
|
|
2. Align \fB\fCNUM_SOCKETS\fR with the estimated CPU usage and CPU limits or system's available resources.
|
|
Examples:
|
|
- If CoreDNS consumes 4 CPUs and 8 CPUs are available, set \fB\fCNUM_SOCKETS\fR to 2.
|
|
- If CoreDNS consumes 8 CPUs and 64 CPUs are available, set \fB\fCNUM_SOCKETS\fR to 8.
|
|
|
|
.SH "LIMITATIONS"
|
|
.PP
|
|
The SO_REUSEPORT socket option is not available for some operating systems. It is available since Linux Kernel 3.9 and
|
|
not available for Windows at all.
|
|
|
|
.PP
|
|
Using this plugin with a system that does not support SO_REUSEPORT will cause an \fB\fCaddress already in use\fR error.
|
|
|