Graphics Administration Guide (July 2008)

For more information, refer to the DBE man page on XdbeScreenVisualInfo().
display power management signaling (DPMS)
Monitors constitute a large percentage of the power used by a workstation even when
not actively in use (i.e., during screen blanking). In order to reduce the power
consumption, the Video Electronic Standards Association (VESA) has defined a Display
Power Management Signaling (DPMS) standard which can be used to greatly reduce
the amount of power being used by a monitor during screen blanking.
The following table is a description of the states that are defined by VESA. The Power
Savings column indicates (roughly) the level of power savings achieved in the given
state. The Recovery Time is the amount of time that the screen takes to return to a
usable state when the screen saver is turned off (by pressing a key or the moving the
mouse).
Table 3-1 Power saving states defined by VESA
Recovery TimePower SavingsStateLevel
NoneNoneOn0
ShortMinimalStand-by1
LongerSubstantialSuspend2
System DependentMaximumOff3
The actual amount of power saved and the recovery time for each of the states is
monitor-dependent and may vary widely. The customer can compensate for this by
choosing an appropriate level for the monitor that is currently in use.
By default, the DPMS level used is the 0 or On (i.e. no power savings).
DPMS should not be confused with screen blanking or screen saving. Screen blanking
will merely cause the screen to go dark. Screen saving will display a changing pattern
on the screen to avoid the burn-in of a static image. Neither of these will cause any
power saving to occur.
shared memory extension (MIT_SHM)
The MIT shared memory extension provides both shared-memory XImages and
shared-memory pixmaps based on the SYSV shared memory primitives.
Shared memory XImages are essentially a version of the XImage interface where the
actual image data is stored in a shared memory segment, and thus need not be moved
through the Xlib interprocess communication channel. For large images, use of this
facility can result in increased performance.
Shared memory pixmaps are a similar concept implemented for the pixmap interface.
Shared memory pixmaps are two-dimensional arrays of pixels in a format specified
by the X Server, where the pixmap data is stored in the shared memory segment. In
44 configuring X server on HP-UX (HP Visualize-FXE)