# Thread Scheduling

## user-level thread
* 對應到一個kernel-level thread

* kernel 不知道user-level thread的存在

* 由thread libary管理

* schedules user-level threads to run on an available LWP

## PCS
* process-contention scope

* Done by thread library

* Many-to-One or Many-to-Many mode

* Linux and Mac OS X

* 4 methods
1. Synchronization
2. Preemption
3. Yielding
4. Time-slicing

## kernel-level thread
* scheduled by the OS

## SCS
* system-contention scope

* Systems using the one-to-one model (such as Windows XP) schedule threads using only SCS.

[HOME PAGE](/bKDZoNkrT9SOBnTvY_aj2Q?view) :sleepy:

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###### tags: `OS` `CSIE`