Editing Thread (computing) (section)

====''M'':1 (user-level threading)====
An ''M'':1 model implies that all application-level threads map to one kernel-level scheduled entity;<ref name="OSConcepts" /> the kernel has no knowledge of the application threads. With this approach, context switching can be done very quickly and, in addition, it can be implemented even on simple kernels which do not support threading. One of the major drawbacks, however, is that it cannot benefit from the hardware acceleration on [[Multithreading (computer hardware)|multithreaded]] processors or [[Multiprocessing|multi-processor]] computers: there is never more than one thread being scheduled at the same time.<ref name="OSConcepts" /> For example: If one of the threads needs to execute an I/O request, the whole process is blocked and the threading advantage cannot be used. The [[GNU Portable Threads]] uses User-level threading, as does [[State Threads]].