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- 1. Kernel-Level Threads In this method, the kernel knows about and manages the threads. No runtime system is needed in this case. Instead of thread table in each process, the kernel has a thread table that keeps track of all threads in the system. In addition, the kernel also maintains the traditional process table to keep track of processes. Operating Systems kernel provides system call to create and manage threads. The implementation of general structure of kernel-level thread is <DIAGRAM> Advantages: • Because kernel has full knowledge of all threads, Scheduler may decide to give more time to a process having large number of threads than process having small number of threads. • Kernel-level threads are especially good for applications that frequently block. Disadvantages: • The kernel-level threads are slow and inefficient. For instance, threads operations are hundreds of times slower than that of user-level threads. • Since kernel must manage and schedule threads as well as processes. It require a full thread control block (TCB) for each thread to maintain information about threads. As a result there is significant overhead and increased in kernel complexity.