Tuning memory resources

Tuning X server performance

The X server program controls what is displayed on the Desktop screen, and handles input from the keyboard and mouse. X clients are application programs which either run on the same machine as the server, or on a remote machine over a network connection. The server displays images on the screen on behalf of the clients and it transmits mouse and keyboard input events to the clients on behalf of the user.

The X server program has several options which affect performance. These options can be added to the invocation of X(X) or Xsco(X) in the file /usr/lib/X11/scologin/Xservers:

If specified, disables support for backing store.

Backing store is a buffer used to store the entire contents of a window. It allows the X server to redraw the entire window rather than requiring the application (X client) to do this. Disabling backing store can save a significant amount of memory but redrawing windows will cause clients to expend more CPU time. This will impact the CPU usage of the machine on which the client is running. If the client is running remotely, it may also generate significantly more network traffic while it redraws the window. This can also cause a noticeable delay while it does this.

-nice value
Specifies the X server's nice value in the range 0 to 39. The default nice value is 0 which gives the most responsive performance by the mouse or other pointing device. See ``Calculation of process priorities'' for a discussion of nice.

If specified, allows the X server to run on any CPU on multiprocessor systems where the video drivers are multithreaded. This can enhance performance on systems with an SCO SMP License by reducing the load on the base processor.

If specified, disables support for save-unders.

Save-unders are temporary buffers that store the contents of windows that other windows, menus, pop-ups, and so on may obscure. Disabling save-unders requires the clients to expend more CPU time redrawing portions of windows, and adds to network load for remote clients.

Next topic: Kernel parameters that affect the X Window System
Previous topic: Using graphical clients on low memory systems

© 2003 Caldera International, Inc. All rights reserved.
SCO OpenServer Release 5.0.7 -- 11 February 2003