Tuning Parameters (Sun Java System Application Server Enterprise Edition 8.2 Performance Tuning Guide)

Sun Java System Application Server Enterprise Edition 8.2 Performance Tuning Guide

Tuning Parameters

Tuning Solaris TCP/IP settings benefits programs that open and close many sockets. Since the Application Server operates with a small fixed set of connections, the performance gain might not be significant.

The following table shows Solaris tuning parameters that affect performance and scalability benchmarking. These values are examples of how to tune your system for best performance.

Table 5–1 Tuning Parameters for Solaris


Parameter	Scope	Default	Tuned Value	Comments
rlim_fd_max	/etc/system	1024	8192	Limit of process open file descriptors. Set to account for expected load (for associated sockets, files, and pipes if any).
rlim_fd_cur	/etc/system	1024	8192
sq_max_size	/etc/system	2	0	Controls streams driver queue size. Setting to 0 makes it infinity so lack of buffer space does not affect performance runs. Set on clients too.
tcp_close_wait_interval	ndd /dev/tcp	240000	60000	Set on clients too.
tcp_time_wait_interval	ndd /dev/tcp	240000	60000
tcp_conn_req_max_q	ndd /dev/tcp	128	1024
tcp_conn_req_max_q0	ndd /dev/tcp	1024	4096
tcp_ip_abort_interval	ndd /dev/tcp	480000	60000
tcp_keepalive_interval	ndd /dev/tcp	7200000	900000	Decrease for high traffic web sites.
tcp_rexmit_interval_initial	ndd /dev/tcp	3000	3000	Increase if retransmission is greater than 30-40%.
tcp_rexmit_interval_max	ndd /dev/tcp	240000	10000
tcp_rexmit_interval_min	ndd /dev/tcp	200	3000
tcp_smallest_anon_port	ndd /dev/tcp	32768	1024	Set on clients, too.
tcp_slow_start_initial	ndd /dev/tcp	1	2	Slightly faster transmission of small amounts of data.
tcp_xmit_hiwat	ndd /dev/tcp	8129	32768	Size of transmit buffer.
tcp_recv_hiwat	ndd /dev/tcp	8129	32768	Size of transmit buffer.
tcp_recv_hiwat	ndd /dev/tcp	8129	32768	Size of receive buffer.
tcp_conn_hash_size	ndd /dev/tcp	512	8192	Size of connection hash table. See Sizing the Connection Hash Table

Sizing the Connection Hash Table

The connection hash table keeps all the information for active TCP connections. Use the following command to get the size of the connection hash table:

ndd -get /dev/tcp tcp_conn_hash

This value does not limit the number of connections, but it can cause connection hashing to take longer. The default size is 512.

To make lookups more efficient, set the value to half of the number of concurrent TCP connections that are expected on the server. You can set this value only in /etc/system, and it becomes effective at boot time.

Use the following command to get the current number of TCP connections.

netstat -nP tcp|wc -l