systune(1M) systune(1M) NAME systune - display and set tunable parameters SYNOPSIS systune [ -bfir ] [ -n name ] [ -p rootpath ] [ variable [ value ] ] DESCRIPTION systune is a tool that enables you to examine and configure your tunable kernel parameters. systune can adjust some parameters in real time and informs you if you need to reboot your system after reconfiguration. It saves the reconfigured kernel in /unix.install, unless the -f option is used. systune has two modes: interactive and noninteractive. Interactive mode allows you to query information about various portions of tunable parameters or to set new values for tunable parameters. Some parameters can be changed while the system is running, and some require a new copy of the kernel to be booted. To enter interactive mode, use the -i option. In noninteractive mode, systune displays the values of one tunable parameter or group of tunable parameters, or allows the value of one tunable parameter to be changed. Note that you will still be prompted for a confirmation when changing a parameter in noninteractive mode. To avoid interacting with the confirmation you must use additional commands, for example: # echo y | systune nproc 400 Noninteractive mode is the default. The options are: -b Both target kernel and the running system are updated with the new values that you specified, if the new values are within the legal range for the parameter specified in /var/sysgen/mtune. The new values with the corresponding tunable variables are also added into /var/sysgen/stune file. This is the default behavior. -f This option forces systune to not save the reconfigured kernel in /unix.install. By default, systune tests to see if /unix.install exists and whether it is identical to the running system. If it is identical, systune makes any changes in /unix.install; otherwise, systune copies the current /unix kernel or the kernel specified by the -n option to /unix.install and makes all changes to the copied kernel. If the copy fails for any reason, such as lack of disk space or the presence of the -f option, the currently running kernel is changed. -i Run systune in interactive mode. When systune is invoked in interactive mode, no parameter values are immediately displayed. Instead, you see the systune prompt: systune-> The commands available in interactive mode are described below. -n name This option specifies an alternate kernel name to tune in place of /unix. -p rootpath If you specify this option, rootpath becomes the starting pathname for systune to check for /var/sysgen/stune and /var/sysgen/mtune. The default rootpath directory is /. -r The new values change on the running system only. If the tunable parameter can not be changed on the running system, nothing is affected. The default is -b. If the name of a variable is specified on the command line, its current value is displayed. If the name of a group is specified on the command line, the names and values of all variables in that group are displayed. If the name of a variable and a value are specified on the command line, the variable's value is changed after verification and confirmation. The systune commands available in interactive mode are: quit Quit systune immediately. Any changes you have made up to that point are saved and cannot be discarded. You must go through and change back any parameters that you do not wish to be changed. all Print information on all tunable parameters. This command displays the same information as systune invoked in noninteractive mode. help Show all the built-in commands and group names. systune lists two commands (help and all) and the groups of kernel tunable parameters. Each group of tunable parameters is organized so that related parameters are kept together. For example, the numproc parameter group contains parameters related to the number of processes allowed to run on the system at any given time. Its parameters are: ncsize = 808 (0x328) ncallout = 40 (0x28) callout_himark = 332 (0x14c) ndquot = 808 (0x328) nproc = 300 (0x12c) parameter_groupname Display information for all the tunable parameters in this group along with their values in decimal numerals and in hexadecimal notation. parameter_name Display information for this tunable parameter only. parameter_name newvalue Set the specified tunable parameter to the new value. For example, to raise the nproc parameter in the numproc parameter group from 300 to 400, follow this example: systune-> nproc 400 nproc = 300 (0x12c) Do you really want to change nproc to 400 (0x190)? (y/n) y In order for the change in parameter nproc to become effective, /unix.install must be moved to /unix and the system rebooted. This message tells you that the change does not take effect until a new kernel with the new value is running on your system. systune always prints a message to inform you if you need to reboot your system for a kernel change to take effect. systune makes all requested changes to the kernel in three places, if possible. (Nondynamically adjustable parameters can be changed in only two out of three places.) The parameters are changed in: + the running kernel image on the workstation + the /unix or /unix.install file + the /var/sysgen/stune file Some sanity checking is performed on the modified kernel parameters to help prevent the creation of kernels that will not function correctly. This checking is performed both by systune and by the lboot(1M) command. For example, some variables have preset minimum and maximum values. Any attempt to change the variable beyond these threshold values results in an error message, and the variable is not changed. BUGS When the system calculates its default value for a systune, the resulting value may be outside the valid range provided by the mtune file. For example, if you set mbmaxpages to 0 (i.e. ask system for default value) then on a 32-bit system with 256M of RAM the default is set to 16384. However the maximum allowed by mtune is 8192. In this example, the system will configure mbmaxpages to 16384 from the default of 0, but it is not possible to assign mbmaxpages > 8192 directly from systune because of the restriction in mtune. Also, systune may not show the user-defined value of syssegsz after reboot. This is due to the fact that the colormap must be calculated and added to syssegsz for machine types IP19, IP20, IP22, and IP32. When systune is called it compares the value of syssegsz in the kernel to the value set in /var/sysgen/stune. If this is done on one of the above machines, they will not match because syssegsz has been altered with the colormap value in the kernel, but not in the stune file. This is a normal function and should not be a concern. If changes are made to system tunable parameters by editing /var/sysgen/stune directly, systune will report that the new values are configured in /unix.install, even though /unix.install has not been reconfigured, and may not even exist. In this case, /unix.install will be configured with the new values the next time autoconfig is run. FILES /var/sysgen/mtune/* system tunable parameters /var/sysgen/stune local settings for system tunable parameters SEE ALSO autoconfig(1M), lboot(1M), mtune(4), stune(4). Page 4