Miscellaneous Configurable Parameters

The following miscellaneous configurable kernel parameters affect various, usually unrelated, HP-UX subsystems.

Disk I/O

default_disk_ir: Specifies whether a write() returns immediately after the data is placed in the disk's write buffer or waits until the data is physically stored on the disk media.
o_sync_is_o_dsync: Specifies whether an open()or fcntl() with the O_SYNC flag set can be converted to the same call with the O_DSYNC flag instead. This controls whether the function can return before updating the file-access.

Kernel-Panic Dumps

alwaysdump: Specifies which classes of system memory are to be dumped if a kernel panic occurs.
dontdump: Specifies which classes of system memory are not to be dumped if a kernel panic occurs.
initmodmax: Maximum number of kernel modules saved by a kernel-panic (system crash) dump operation.

Multi-Processor Spinlocks

These parameters control the allocation of spinlocks for use in systems equipped with multiple processors:

bufcache_hash_locks: Buffer-cache spinlock pool
chanq_hash_locks: Channel queue spinlock pool
ftable_hash_locks: File-table spinlock pool
io_ports_hash_locks: I/O-port spinlock pool
pfdat_hash_locks: Pfdat spinlock pool
region_hash_locks: Process-region spinlock pool
sysv_hash_locks: System V Inter-process-communication spinlock pool
vnode_cd_hash_locks: Vnode clean/dirty spinlock pool
vnode_hash_locks: Vnode spinlock pool

See spinlock parameters for more information.

Reserved, Unlockable System Memory

unlockable_mem: Specifies how much system memory is to be reserved for system overhead and virtual memory management, and therefore cannot be locked by user processes.

System Clock

dst: Specifies the style of Daylight Savings Time to be used, if any.
timezone: Specifies the relationship between the local time zone and Coordinated Universal Time (UCT), also sometimes called Greenwich Mean Time or GMT.

Other Parameters

clicreservedmem: Specifies how many bytes of system memory are to be reserved for I/O-mapping use by user processes in high-speed, distributed-server environments such as those used for running large database-processing programs.
create_fastlinks: Tells the kernel to create symbolic links in a more recent format to improve access speed by reducing disk-block accesses during path look-up sequences.
eqmemsize: Specifies how many pages of memory are to be reserved for use as equivalently mapped memory, used mostly for DMA transfers.
ksi_alloc_max: Specifies the system-wide limit of how many queued signals can be allocated.
ksi_send_max: Specifies how manyqueued signals a process can send and have pending at one or more receivers.
max_async_ports: System-wide maximum number of ports to the asynchronous disk I/O driver that processes can have open at any given time.
maxusers: Used by other system parameter definitions to allocate system resources based on the maximum number of users expected to be logged in on the system.
ncallout: Limits the number of timeouts that can be scheduled by the kernel at any given time.
ncdnode: Limits the number of entries in the vnode table and therefore the maximum number of open CD-ROM file-system nodes that can be in memory.
nclist: Specifies how many cblocks are to be allocated for use in data transfers through tty and pty devices.
.ndilbuffers: Limits the number of Device I/O Library devices that can be open at any given time.
npty: Limits the number of pseudo-tty entries allowed on the system at any given time.
nstrtel: Determines how many telnet-session device files are available on the system.
o_sync_is_o_dsync: Enables or disables translation of O_SYNC to O_DSYNC in open() and fcntl() system calls.
pfail_enabled: Determines whether the power-fail routines are to be used or not upon loss of AC line power. Applies only on Series 800 systems that are equipped with power-fail hardware.
public_shlibs: Enables (or disables) public protection IDs on shared libraries for improved system performance.
rtsched_numpri: Specifies how many distinct real-time interrupt priorities are available on the system.
sendfile_max: Limits the amount of buffer cache that can be used by the sendfile() system call on HP-UX web servers.
scroll_lines: Defines the number of lines that can be scrolled on the internal terminal emulator system console.