The Story of Jay

프로그램을 빌드하는데 4가지 단계 단계별 빌드 과정 #include int main(int argc, char **argv) { printf("Hello Main function\n"); return 0; } //main.c 파일 생성 //Processing 단계 main.i 파일을 생성 (-E 옵션: 전처리 과정의 결과 화면에 보여줌) ➜ 55_blog gcc -E main.c > main.i ➜ 55_blog ls main.c main.i //compiling 단계 main.s 파일 생성 (-S 옵션: 전처리된 파일을 어셈블리 파일로 컴파일까지 수행) ➜ 55_blog gcc -S main.i ➜ 55_blog ls main.c main.i main.s //Assembly 단계 as로 .s파일을 .o..

exec(): When an exec() system call is invoked, the program specified in the parameter to exec() will replace the entire process - including all threads. exec 를 사용하게 되면 기존에 사용하던 process 를 대체하게 되서 exec_2 를 실행하게 되고 다시 기존 exec process로 돌아가서 실행을 하지 않는다. 따라서 마지막 10번째 come back to exec process 는 프린트 되지 않는다.

fork() : Create new process, Clone current process // system call ->Have exactly the same stack (sequence of function calls) ->Have same virtual memory ( so pointer and other data is preserved) ->No argument ->Return process Id of the child process -> After creation of the process both parent and child process starts execution from next the instruction fork() > 0 //Successful fork() < 0 // Error..

Stack: Fixed memory, local variable, and function - Stack overflow() Heap: Dynamic memory // Malloc(), calloc(), realloc(), free() malloc: No initialization calloc: initialization int *B = (int*)realloc(NULL, n*sizeof(int)); // equivalent to malloc ------- Code | Global | Stack | Heap

Priority inversion is an operating system scenario in which a higher priority task is preempted by a lower priority task. Problem: Higher priority task is blocked by a lower priority one. Solutions: 1. Priority inheritance protocol: When a task blocks one or more higher-priority tasks it temporarily inherits the highest priority of the blocked tasks. - PIP does not prevent deadlock. It also cann..

Thread is a basic unit of execution so each program may have a number of processes associated with it and each process can have a number of threads executing in it. - A thread is a basic unit of CPU utilization It comprises: A thread ID/ A program counter/ A register set / A stack - It shares with other threads belonging to the same process its code section, data section and other operating-syst..

1. static ( global /function): only visible within its own translation unit. static (local variable): persistent across function calls and only visible within its function. Need the initialization. Static 은 메모리 구조에서 Data 영역에 저장이 된다. 프로그램 시작과 동시에 할당이 되고 프로그램이 종료되어야 메모리에서 지워 진다. 2. volatile: The volatile keyword prevents the compiler from performing optimization on code involving volatile objects,..