![]() If there are threads executing at high priority, a thread in background processing mode may not be scheduled promptly, but it will never be starved.Įach thread can enter background processing mode independently using SetThreadPriority. When a thread is in background processing mode, it should minimize sharing resources such as critical sections, heaps, and handles with other threads in the process, otherwise priority inversions can occur. ![]() If a process is in background processing mode, the new threads it creates will also be in background processing mode. Processes that perform background work should use the PROCESS_MODE_BACKGROUND_BEGIN and PROCESS_MODE_BACKGROUND_END values to adjust their resource scheduling priorities processes that interact with the user should not use PROCESS_MODE_BACKGROUND_BEGIN. For processes that perform background work such as file I/O, network I/O, or data processing, it is not sufficient to adjust the CPU scheduling priority even an idle CPU priority process can easily interfere with system responsiveness when it uses the disk and memory. The *_PRIORITY_CLASS values affect the CPU scheduling priority of the process. SetThreadPriority function enables setting the base priority level of a thread relative to the priority class of its process. ![]() The system uses the base priority level of all executable threads to determine which thread gets the next slice of CPU time. To get extended error information, callĮvery thread has a base priority level determined by the thread's priority value and the priority class of its process. If the function fails, the return value is zero. If the function succeeds, the return value is nonzero. For example, a real-time process that executes for more than a very brief interval can cause disk caches not to flush or cause the mouse to be unresponsive. The threads of the process preempt the threads of all other processes, including operating system processes performing important tasks. Process that has the highest possible priority. The function fails if the process is not in background processing mode. This value can be specified only if hProcess is a handle to the current process. The system restores the resource scheduling priorities of the process (and its threads) as they were before the process entered background processing mode. Windows Server 2003 and Windows XP: This value is not supported.Įnd background processing mode. The function fails if the process is already in background processing mode. The system lowers the resource scheduling priorities of the process (and its threads) so that it can perform background work without significantly affecting activity in the foreground. Process with no special scheduling needs.īegin background processing mode. The idle-priority class is inherited by child processes. The threads of the process are preempted by the threads of any process running in a higher priority class. Process whose threads run only when the system is idle. ![]() Use extreme care when using the high-priority class, because a high-priority class application can use nearly all available CPU time. An example is the Task List, which must respond quickly when called by the user, regardless of the load on the operating system. The threads of the process preempt the threads of normal or idle priority class processes. Process that performs time-critical tasks that must be executed immediately. Process that has priority above IDLE_PRIORITY_CLASS but below NORMAL_PRIORITY_CLASS. Process that has priority above NORMAL_PRIORITY_CLASS but below HIGH_PRIORITY_CLASS. This parameter can be one of the following values. The handle must have the PROCESS_SET_INFORMATION access right. This value together with the priority value of each thread of the process determines each thread's base priority level. Sets the priority class for the specified process.
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