QIO Configuration and Management Manual

Configuring the QIO Subsystem
QIO Configuration and Management Manual—424717-008
2-2
Understanding QIO Memory Configuration
Understanding QIO Memory Configuration
By default, QIO memory is stored in a flat memory space known as user-addressable
data space.
Before you try to reconfigure your QIO subsystem you must understand user-
addressable data space and how QIO works within it.
User-Addressable Data Space
User-addressable data space is flat, nonprivileged memory space. Flat memory
appears to a program as one large addressable space. Each native process has a
user-addressable data area that it accesses. By default, the allocated space for the flat
segment memory space begins at 0x4E00.0000 and grows toward the lower address
of 0x0800.0000.
Elements of this area are:

Segments for process globals and the process heap

QIO shared memory

An unassigned flat memory space

A memory segment that is available for use by programs
Following are discussions of each of these elements.
Note. On Integrity NonStop NS-series servers, HP recommends that you configure QIO to run
in system data space unless your environment is using more than 256 MB of QIO shared
memory space. On NonStop S-series servers, HP also recommends that you consider
configuring QIO to run in system space unless your environment is using more than 128 MB of
QIO shared memory space.