Recommended hotfix for multi CPU systems, XP SP2
Posted: Wed Dec 20, 2006 7:23 pm
http://support.microsoft.com/default.aspx/kb/896256
Released today. Download here.Computers that are running Windows XP Service Pack 2 and that are equipped with multiple processors that support processor power management features may experience decreased performance
Computers that are equipped with multiple processors that support processor power management features, such as Advanced Configuration and Power Interface (ACPI) processor performance states, require Microsoft Windows XP Service Pack 2 (SP2). Additional updates are available to optimize performance and behavior on computers that are running Windows XP SP2. Without these updates, computers that are equipped with these power management-capable, mobile, dual-core processors may experience decreased performance or unexpected behavior.
Windows XP SP2 is required on computers that have multiple CPUs that support ACPI processor performance states. This requirement includes computers that support the following items:
• Multiple physical sockets
• Multiple-core designs
• Multiple logical threads, such as Intel hyper-threading technology
Because Windows XP was not originally designed to support performance states on multiprocessor configurations, changes are required to correctly realize this support on multiprocessor systems. Windows XP Service Pack 2 includes the required changes to the kernel power manager. These changes make sure that Windows XP correctly functions on multiprocessor systems with processor performance states.