Technical Features New To Windows Vista - Kernel and Core OS Changes

Kernel and Core OS Changes

• The new Kernel Transaction Manager enables atomic transaction operations across different types of objects, most significantly file system and registry operations.

• The memory manager and processes scheduler have been improved. The scheduler was modified to use the cycle counter register of modern processors to keep track of exactly how many CPU cycles a thread has executed, rather than just using an interval-timer interrupt routine. This new CPU cycle-based thread scheduling gives a greater fairness and more deterministic app behavior. Many kernel data structures and algorithms have been rewritten. Lookup algorithms now run in constant time, instead of linear time as with previous versions.
• Windows Vista includes support for condition variables and reader-writer locks.
• Process creation overhead is reduced by significant improvements to DLL address-resolving schemes.
• Windows Vista introduces a Protected Process, which differs from usual processes in the sense that other processes cannot manipulate the state of such a process, nor can threads from other processes be introduced in it. A Protected Process has enhanced access to DRM-functions of Windows Vista. However, currently, only the applications using Protected Video Path can create Protected Processes.
• Thread Pools have been upgraded to support multiple pools per process, as well as to reduce performance overhead using thread recycling. It also includes Cleanup Groups that allow clean up of pending thread-pool requests on process shutdown.
• Threaded DPC, conversely to an ordinary DPC (Deferred Procedure Call), decreases the system latency improving the performance of time-sensitive applications, such as audio or video playback.
• Data Redirection: Also known as data virtualization, this virtualizes the registry and certain parts of the file system for applications running in the protected user context if User Account Control is turned on, enabling legacy applications to run in non-administrator accounts. It automatically creates private copies of files that an application can use when it does not have permission to access the original files. This facilitates stronger file security and helps applications not written with the least user access principle in mind to run under stronger restrictions. Registry virtualization isolates write operations that have a global impact to a per-user location. Reads and writes in the HKLM\Software section of the Registry by user-mode applications while running as a standard user, as well as to folders such as "Program Files", are "redirected" to the user's profile. The process of reading and writing on the profile data and not on the application-intended location is completely transparent to the application.
• Windows Vista supports the PCI Express 1.1 specification, including extended configuration space and segmentation. PCI Express registers, including capability registers, are supported, along with save and restore of configuration data.
• Native support and generic driver for Advanced Host Controller Interface (AHCI) specification for Serial ATA drives, SATA Native Command Queuing, Hot plugging, and AHCI Link Power Management.
• Full support for the ACPI 2.0 specification, and parts of ACPI 3.0. Support for throttling power usage of individual devices has been improved.
• Kernel-mode Plug-And-Play enhancements include support for PCI multilevel rebalance, partial arbitration of resources to support PCI subtractive bridges, asynchronous device start and enumeration operations to speed system startup, support for setting and retrieving custom properties on a device, an enhanced ejection API to allow the caller to determine if and when a device has been successfully ejected, and diagnostic tracing to facilitate improved reliability.
• The startup process for Windows Vista has changed completely in comparison to earlier versions of Windows. The NTLDR boot loader has been replaced by a more flexible system, with NTLDR's functionality split between two new components: winload.exe and Windows Boot Manager. A notable change is that the Windows Boot Manager is invoked by pressing the space bar instead of the F8 function key. The F8 key still remains assigned for advanced boot options once the Windows Boot Manager menu appears.
• On UEFI systems, beginning with Windows Vista Service Pack 1, the x64 version of Windows Vista has the ability to boot from a disk with a GUID Partition Table.
• Windows Vista includes a completely overhauled and rewritten Event logging subsystem, known as Windows Event Log which is XML-based and allows applications to more precisely log events, offers better views, filtering and categorization by criteria, automatic log forwarding, centrally logging and managing events from a single computer and remote access.
• Windows Vista includes an overhauled Task Scheduler that uses hierarchical folders of tasks. The Task Scheduler can run programs, send email, or display a message. The Task Scheduler can also now be triggered by an XPath expression for filtering events from the Windows Event Log, and can respond to a workstation's lock or unlock, and as well as the connection or disconnection to the machine from a Remote Desktop. The Task Scheduler tasks can be scripted in VBScript, JScript, or PowerShell.
• Restart Manager: The Restart Manager works with Microsoft's update tools and websites to detect processes that have files in use and to gracefully stop and restart services to reduce the number of reboots required after applying updates as far as possible for higher levels of the software stack. Kernel updates, logically, still require the system to be restarted. In addition, the Restart Manager provides a mechanism for applications to stop and then restart programs. Applications that are written specifically to take advantage of the new Restart Manager features using the API can be restarted and restored to the same state and with the same data as before the restart. Using the Application Recovery and Restart APIs in conjunction with the Restart Manager enables applications to control what actions are taken on their behalf by the system when they fail or crash such as recovering unsaved data or documents, restarting the application, and diagnosing and reporting the problem using Windows Error Reporting.
• When shutting down or restarting Windows, previous Windows versions either forcibly terminated applications after waiting for few seconds, or allowed applications to entirely cancel shutdown without informing the user. Windows Vista now informs the user in a full-screen interface if there are running applications when exiting Windows or allows continuing with or cancelling the initiated shutdown. The reason registered, if any, for cancelling a shutdown by an application using the new ShutdownBlockReasonCreate API is also displayed.
• Clean service shutdown: Services in Windows Vista have the capability of delaying the system shutdown in order to properly flush data and finish current operations. If the service stops responding, the system terminates it after 3 minutes. Crashes and restart problems are drastically reduced since the Service Control Manager is not terminated by a forced shutdown anymore.