HP-UX Reference (11i v2 03/08) - 5 Miscellaneous Topics, 7 Device (Special) Files, 9 General Information, Index (vol 9)

nstrpty(5) nstrpty(5)

(Tunable Kernel Parameters)

NAME

nstrpty - maximum number of streams-based pseudo-teletypes (ptys)

VALUES

Default

nstrpty = 10

Allowed Values

Minimum : 1

Maximum : System memory size

DESCRIPTION

nstrpty is the number of streams-based pseudo-teletype (pty) drivers that a system can support. The

pty driver provides support for a device-pair called a pseudo terminal. A pseudo terminal is a pair of

character devices, a master device, and a slave device. These allow communication between an applica-

tion process and a server process. When sending data to pty devices (such as windows), a pty device

must exist for every window that is open at any given time.

nstrpty should be set to a value that is equal to, or greater than, the number of pty devices on the sys-

tem that will be using streams-based I/O pipes. Using a parameter value signiﬁcantly larger than the

number of ptys is not recommended. nstrpty is used when creating data structures in the kernel to

support streams-based ptys, and an excessively large value wastes kernel memory space.

Who Is Expected to Change This Tunable?

Anyone.

Restrictions on Changing

Changes to this tunable take effect at the next reboot.

When Should the Value of This Tunable Be Raised?

This tunable value needs to be raised when the system runs out of ptys.

What Are the Side Effects of Raising the Value?

More system memory is used.

When Should the Value of This Tunable Be Lowered?

This value should be lowered when a minimal system is being created.

What Are the Side Effects of Lowering the Value?

The system may run out of pttys.

WARNINGS

All HP-UX kernel tunable parameters are release speciﬁc. This parameter may be removed or have its

meaning changed in future releases of HP-UX.

AUTHOR

nstrpty was developed by HP.