[공부정리] Threads and Microkernels

Threads

- A unit of execution of in a process (by  a group of instructions) 프로세스 안에서 실행하는 단위

- Has an execution state (running, ready, etc)

 

Multithreading

- Operating system supports one or more threads of execution within a single process

 

Process VS Thread

Process

- Have a virtual address space which holds the process image 프로세스 이미지를 저장할 가장 주소 공간을 가진다

- Protected access to processors, other processes, files, I/O resources

- consists of (Code, Data, Stack, Memory for registers context)

Thread

- Access to the memory and resources of its process 프로세스의 메모리 및 리소스에 대한 액세스

- consists of (Stack, Memory for registers context)

 

Benefits of Threads

- Takes less time to create a new thread than a process

- Less time to terminate a thread than a process

- Less time to switch between two threads within the same process

- Less time to communicate between threads in the same process than to communicate between processes

- 같은 프로세스에 있는 쓰레드들은 메모리와 파일들을 공유할 수 있기 때문에 커널을 호출하지 않고 서로간의 통신이 가능하다.

 

Microkernels

- Small sized kernel

- Contains only essential core operating systems functions

 : Process management

 : Basic memory management capability

- Many services traditionally included in the operating system are now external subsystems (user processes) 예전부터 운영 체제에 포함 된 많은 서비스가 지금은 외부 하위 시스템이다.

 

Benefits of Microkernel Organization

- Uniform interface on request made by a process 프로세스에서 요청에 대해 균일한 인터페이스

- Extensibility

- Flexibility

- Portability

- Reliability

- Distributed system support

 

Disadvantages of Microkernel

- Performance : working slower than a monolithic kernel

- 성능 차이는 마이크로커널의 설계에 따라 많이 줄어들 수도 있다.