Optimize Solaris’s TCP stack

Apparently Solaris comes with some crummy settings for web hosting. Here are the settings I have used to improve our web performance at our service.

victori@fab40:/etc/rc2.d# netstat -sP tcp | grep -i drop
	tcpTimRetransDrop   =  6029	tcpTimKeepalive     =  2467
	tcpListenDrop       = 27327	tcpListenDropQ0     =     0
	tcpHalfOpenDrop     =     0	tcpOutSackRetrans   = 99988

If tcpListenDrop is above 0, you have more connections than the system can handle with the default settings. Increasing tcp_conn_req_max_q accordingly should fix the issue. Raise the number incrementally until tcpListenDrop stops gradually increasing.

The tcp_conn_req_max_q default is 1024.

/usr/sbin/ndd -set /dev/tcp tcp_conn_req_max_q 8192
/usr/sbin/ndd -set /dev/tcp tcp_conn_req_max_q0 8192

Lower the anonymous port range to support the larger connection queue that was defined.

/usr/sbin/ndd -set /dev/tcp tcp_smallest_anon_port 2048

Up the buffer size for transmissions, to you know….. actually make use of that 100mbit connection?

/usr/sbin/ndd -set /dev/tcp tcp_xmit_hiwat 1048576
/usr/sbin/ndd -set /dev/tcp tcp_recv_hiwat 1048576
/usr/sbin/ndd -set /dev/tcp tcp_max_buf 2097152

To persist these settings across a reboot just write out the contents to /etc/rc2.d/S99netoptimize bash file

I was told Solaris was configured out of the box for today’s hardware? wtf?

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