TNS/R Native Application Migration Guide

Introduction to Native Mode

TNS/R Native Application Migration Guide—523745-001

1-16

Kernel-Managed Swap Facility (KMSF)

A swap file is a disk file used for copying data between physical memory and disk

storage. Pages of memory are swapped to disk when physical memory is needed, and

swapped back to physical memory when the data is needed.

Beginning with the D4x and Gxx RVUs, the Kernel-Managed Swap Facility (KMSF)

manages virtual memory using swap files under its control. Each processor in a node

has one or more kernel-managed swap files that provides the swap space needed by

TNS and native processes running on the processor. KMSF manages:

•

The globals-heap segment and SRL instance data segments for native processes

•

The main RISC stack segment and the privileged RISC stack segment for TNS and

native processes

•

The user data segment for TNS processes

•

The default extended data segment for TNS processes, unless it is explicitly

specified not to be managed by KMSF

•

Program-allocated extended data segments (selectable or flat segments), such as

those allocated with the SEGMENT_ALLOCATE_ procedure, for TNS and native

processes, unless they are explicitly specified not to be managed by KMSF

For details on how programs can specify that their extended data segments not be

managed by KMSF, see the SEGMENT_ALLOCATE_ procedure in the Guardian

Procedure Calls Reference Manual.

KMSF benefits include speeding up process creation and deletion and reducing the

total size of swap files on disks.

You configure and manage the swap volumes used by KMSF with the NSKCOM utility.

KMSF emits EMS warnings when swap space is running low. For more information on

KMSF, see the Kernel-Managed Swap Facility (KMSF) Manual.

KMSF changes the control you have over process swap files. You can still specify the

space you need, but you cannot decide at process creation where the data is

swapped. As a result of this change, commands and procedures related to swap files

might have reduced or no effects. Swap file information from procedures and

commands might have different meanings for native processes. Table 1-2 on

page 1-17, provides an overview of these changes. For more details, see the specific

procedure or command.