Книга: Microsoft Windows Embedded CE 6.0 Exam Preparation Kit

Managing Thread Priority

Managing Thread Priority

Each thread has a priority value ranging from zero to 255, which determines how the system schedules the thread to run in relationship to all other threads within the process and between processes. On Windows Embedded CE, the core Win32 API includes four thread management functions that set the priority of a thread as follows.

? Base priority levels Use the SetThreadPriority and SetThreadPriority functions to manage the thread priority at levels compatible with early versions of Windows Embedded CE (zero through seven).

? All priority levels Use the CeSetThreadPriority and CeGetThreadPriority functions to manage the thread priority at all levels (zero through 255).

It is important to keep in mind that thread priorities define a relationship between threads. Assigning a high thread priority can be detrimental to the system if other important threads run with lower priority. You might achieve better application behavior by using a lower priority value. Performance testing with different priority values is a reliable manner of identifying the best priority level for a thread in an application or driver. However, testing 256 different priority values is not efficient. Choose an appropriate priority range for your threads according to the purpose of your driver or application as listed in Table 3-10.

Table 3-10 Thread priority ranges

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