Diagnostic Functionality
Windows implements several built-in diagnostic scenarios and utilities. Some examples include:
Disk diagnostics, which include the presence of Self-Monitoring Analysis and Reporting Technology (SMART) code inside the storage class driver (%SystemRoot%\System32\Driver\Classspnp.sys) to monitor disk health. WDI notifies and guides the user through data backup after an impending disk failure is detected. In addition, Windows monitors application crashes caused by disk corruptions in critical system files. The diagnostic uses the Windows File Protection mechanism to automatically restore such damaged system files from a backup cache when possible. For more information on Windows storage management, see Chapter 9, “Storage Management,” in Part 2.
Network diagnostics and troubleshooting extends WDI to handle different classes of networking-related problems, such as file sharing, Internet access, wireless networks, third-party firewalls, and general network connectivity. For more information on networking, see Chapter 7.
Resource exhaustion prevention, which includes Windows memory leak diagnosis and Windows resource exhaustion detection and resolution. These diagnostics can detect when the commit limit is approaching its maximum and alert the user of the situation, including the top memory and resource consumers. The user can then choose to terminate these applications to attempt to free some resources. For more information on the commit limit and virtual memory, see Chapter 10, “Memory Management,” in Part 2.
Windows memory diagnostic tool, which can be manually executed by the user from the Boot Manager on startup or automatically recommended by Windows Error Reporting (WER) after a system crash that was analyzed as potentially the result of faulty RAM. For more information on the boot process, see Chapter 13 in Part 2.
Windows startup repair tool, which attempts to automatically fix certain classes of errors commonly responsible for users being unable to boot the system, such as incorrect BCD settings, damaged disk structures such as the MBR or boot sector, and faulty drivers. When system boot is unsuccessful, the Boot Manager automatically launches the startup repair tool, if it is installed, which also includes manual recovery options and access to a command prompt. For more information on the startup repair tool, see Chapter 13 in Part 2.
Windows performance diagnostics, which include Windows boot performance diagnostics, Windows shutdown performance diagnostics, Windows standby/resume performance diagnostics, and Windows system responsiveness performance diagnostics. Based on certain timing thresholds and the internal behavioral expectations of these mechanisms, Windows can detect problems caused by slow performance and log them to the Event Log, which in turn is used by WDI to provide resolutions and walkthroughs for the user to attempt to fix the problem.
Program Compatibility Assistant (PCA), which enables legacy applications to execute on newer Windows versions despite compatibility problems. PCA detects application installation failures caused by a mismatch during version checks and run-time failures caused by deprecated binaries and User Account Control (UAC) settings. PCA attempts to recover from these failures by applying the appropriate compatibility setting for the application, which takes effect during the next run. In addition, PCA maintains a database of programs with known compatibility issues and informs the users about potential problems at program startup.
Conclusion
So far, we’ve examined the overall structure of Windows, the core system mechanisms on which the structure is built, and core management mechanisms. With this foundation laid, we’re ready to explore the individual executive components in more detail, starting with processes and threads.
Chapter 5. Processes, Threads, and Jobs
In this chapter, we’ll explain the data structures and algorithms that deal with processes, threads, and jobs in the Microsoft Windows operating system. The first section focuses on the internal structures that make up a process. The second section outlines the steps involved in creating a process (and its initial thread). The internals of threads and thread scheduling are then described. The chapter concludes with a description of jobs.
