About tunable parameters

Tunable system parameters affect the settings of various system tables. The default tunable parameter values are acceptable for most configurations and applications. If your application has special performance needs, you might have to experiment with different combinations of parameter values to find an optimal set.

There are two types of tunable parameters: internet (TCP/IP), and kernel.

• Internet (TCP/IP) tunable parameters reside in /etc/inet/inet.dfl. All internet tunable parameters have lower-case names (for example: udpprintfs, tcp_2msl, ipforwarding). Internet tunable parameters should be modified using the inconfig(1Mtcp) command. A reboot or rebuild is not required for changes to take effect, but is generally recommended. (If, for example, you turn off ipforwarding on a router without rebooting, erratic behavior and error messages can result.)

• Kernel system tunable parameters reside in the kernel configuration directories /etc/conf/mtune.d (see Mtune(4dsp)) and /etc/conf/autotune.d. (see Autotune(4dsp) ). Kernel system tunable parameters all have upper-case names (for example; DMA_PERCENT, MAXRSS). The idtune(1M) command or the SCOadmin System Tuner (see ``Using the System Tuner'') are used to examine and modify kernel tunable parameters. You must use idbuild(1M) to rebuild your system and reboot in order for changes to become effective.

Some parameters are autotuned and do not normally require manual tuning.