Kernel-Managed Swap Facility (KMSF) Manual

Introduction
Kernel-Managed Swap Facility (KMSF) Manual—425824-005
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Kernel-Managed Swap (KMS) Files
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Can be used in addition to KMS files
Kernel-Managed Swap (KMS) Files
Kernel-managed swap (KMS) files:
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Are a required part of the NonStop operating system
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Are defined and managed by the KMSF
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Are dedicated to a single processor in the system and all processes running on the
processor
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Are opened only once and are then remain available to all processes running on
the processor, including processes started after the swap file is opened
Benefits of Using KMS Files for Virtual Memory
KMS files offer the following benefits over conventional swap files:
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Speed up process creation and deletion because they are only opened once and
then are available to all processes running on the processor.
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Use much less disk space than conventional swap files when they are used to
back the large, sparsely populated address space used by shared run-time
libraries (SRLs) or dynamic link libraries (DLLs).
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Reduce the time required to resize a segment. The KMSF implementation of
segment resizing requires neither I/O nor dispatches of other processes.
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Can be centralized, making it easier to manage swap space for all processes on
the system.
Effect of KMS Files On System Operations
The proper configuration and management of KMS space is vital to system operations
because a lack of available KMS space can cause a processor that has run out of
physical memory to halt.
Those responsible for system administration must plan for and configure KMS files.
Using the guidelines in Section 2, Configuring KMSF, administrators must decide:
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How much swap space is needed
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Where to place swap files
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What guidelines they need to create for operations staff on monitoring and altering
swap files
Operations staff must monitor KMSF and operator messages to spot potential
problems and dynamically add swap space as needed. Event Management Service
(EMS) messages are generated to alert staff to swap files that have reached a