Kernel parameters that affect the X Window System

Although the following kernel parameters do not directly affect performance, they are important for the correct operation of the X Window System, the Desktop, and X terminals. You may be unable to start an X client if you do not enough of these resources configured. See ``Configuring kernel parameters'' for details of how to change the value of kernel parameters.

MAX_PROC

Set the value of this parameter to 0 to allow the process table to grow dynamically.

MAXUP

Limits the number of processes that the system will run on behalf of a user. Each window requires at least one process. Note that local applications running in a window may start several additional processes.

NOFILES

Specifies the maximum number of files that a process (including the X server) can have open simultaneously. This limits the number of X clients that can be started because the X server opens a file descriptor to each client. In addition, the X server requires about 10 file descriptors in order to read fonts, color maps, and so on.

NSPTTYS

Allow at least as many pseudo terminals as the number of windows that will be opened for use on the console, by X terminals, and X clients. If necessary, you can change the number of pseudo terminals configured for use using the mkdev ptty command.

NSTREAM

Allow at least four stream heads for the X server plus four for each client connection. NSTREAM should be approximately four times the value of NSPTTYS.

NSTRPAGES

This parameter controls the maximum number of 4KB pages of memory that can be dynamically allocated for use by STREAMS messages. Allow at least 125 pages plus 125 pages for each X terminal that is supported.

NUMSP

Two stream pipes are needed for the X server plus two for each local X client. NUMSP should be approximately twice the value of NSPTTYS.