Description

The PS_AVAILABLE_CPUS_CHANGE_CALLBACK function is a callback routine that is called when the set of available CPUs changes for a process or the system.

Parameters

Context [in, optional]

A pointer to driver-defined context information that was specified when the callback was registered with PsRegisterProcessAvailableCpusChangeNotification or PsRegisterSystemAvailableCpusChangeNotification.

SequenceNumber [in]

The current sequence number for the available CPUs. This value increments whenever the set of available CPUs changes.

Remarks

This callback function is implemented by the driver and is called by the system when CPU availability changes.

The callback can be invoked at IRQL from PASSIVE_LEVEL to DISPATCH_LEVEL, so the implementation must be able to run at DISPATCH_LEVEL.

When the Callback is Invoked

The callback is invoked when:

• CPUs are added or removed from the system (hotplug scenarios)
• Process affinity is modified (for process-specific registrations)
• System-wide CPU availability changes (for system registrations)
• CPU cores go online or offline
• Processor groups are modified

Implementation Guidelines

• The callback should complete quickly since it may be called at DISPATCH_LEVEL
• Avoid blocking operations or lengthy processing
• Use the SequenceNumber parameter to detect and handle changes efficiently
• Query the current CPU availability using PsQueryProcessAvailableCpus or PsQuerySystemAvailableCpus if needed

See also

PsRegisterProcessAvailableCpusChangeNotification

PsRegisterSystemAvailableCpusChangeNotification

PsUnregisterAvailableCpusChangeNotification

PsQueryProcessAvailableCpus

PsQuerySystemAvailableCpus