HP-UX 11i September 2001 Release Notes

Process, Threads, Memory, and Kernel Parameters
Dynamic Tunables (new at 11i original release)
Chapter 8
136
Dynamic Tunables (new at 11i original release)
A new facility has been added which will allow the retrieving of all tunable values and
the setting of a limited number of tunables. If a tunable is dynamic, a change will take
place immediately, without the need to reboot the system. Such changes will persist
across reboots.
Three parts of the system have been changed to allow retrieving and setting of dynamic
tunable values:
• System Administration Manager (SAM). For details, see “Changes to System
Administration Manager (SAM) (updated for June 2001)” on page 118 in this
document and the SAM Online Help Facility.
• kmtune. This command has been enhanced to allow the changing of dynamic
tunables. See the kmtune (1M) manpage for further details.
• Three new system calls have been added: gettune (2), settune (2) and tuneinfo (2). See
the manpage for each of these new system calls for their function and use.
Currently, the following tunables are dynamic:
• maxuprc- Maximum number of user processes
• msgmax- Message maximum size in bytes
• msgmnb - Maximum number of bytes on a message queue
• shmmax - Maximum shared memory segment size in bytes
• shmseg - Shared memory segments per process
• maxtsiz- Maximum text segment size in bytes for 32 bit programs
• maxtsiz_64bit- Maximum text segment size in bytes for 64 bit programs
• maxfiles_lim - Hard file limit per process
• core_addshmem_read -Include readable shared memory in process core dump
• core_addshmem_write -Include writable shared memory in process core dump
For more information, see the white paper Dynamically Tunable Kernel Parameters in
HP-UX 11i at http://docs.hp.com.