Design ‐ Process State Machine

Process States and Transitions

A process has the following possible states:

Below are the possible transitions between states. Transitions are expressed using the following format:

START_STATE -> EVENT_NAME -> NEW_STATE

IDLE -> ASSIGN_TO_CPU -> RUNNING
IDLE -> TERMINATE_FROM_STARVATION -> ENDED
RUNNING -> REMOVE_FROM_CPU -> IDLE
RUNNING -> REQUEST_IO -> BLOCKED_ON_CPU_IO_REQUESTED
RUNNING -> PAGE_FAULT -> BLOCKED_ON_CPU_PAGE_FAULT
RUNNING -> TERMINATE_GRACEFULLY -> ENDED
BLOCKED_ON_CPU_IO_REQUESTED -> IO_AVAILABLE -> BLOCKED_ON_CPU_IO_AVAILABLE
BLOCKED_ON_CPU_IO_REQUESTED-> REMOVE_FROM_CPU -> BLOCKED_OFF_CPU_IO_REQUESTED
BLOCKED_ON_CPU_IO_AVAILABLE -> IO_DELIVERED -> RUNNING
BLOCKED_ON_CPU_IO_AVAILABLE -> REMOVE_FROM_CPU -> BLOCKED_OFF_CPU_IO_AVAILABLE
BLOCKED_ON_CPU_IO_AVAILABLE -> TERMINATE_FROM_STARVATION -> ENDED
BLOCKED_ON_CPU_PAGE_FAULT -> PAGE_AVAILABLE -> RUNNING
BLOCKED_ON_CPU_PAGE_FAULT -> REMOVE_FROM_CPU -> IDLE
BLOCKED_ON_CPU_PAGE_FAULT -> TERMINATE_FROM_STARVATION -> ENDED
BLOCKED_OFF_CPU_IO_REQUESTED -> IO_AVAILABLE -> BLOCKED_OFF_CPU_IO_AVAILABLE
BLOCKED_OFF_CPU_IO_REQUESTED -> ASSIGN_TO_CPU -> BLOCKED_ON_CPU_IO_REQUESTED
BLOCKED_OFF_CPU_IO_AVAILABLE -> IO_DELIVERED -> IDLE
BLOCKED_OFF_CPU_IO_AVAILABLE -> ASSIGN_TO_CPU -> BLOCKED_ON_CPU_IO_AVAILABLE
BLOCKED_OFF_CPU_IO_AVAILABLE -> TERMINATE_FROM_STARVATION -> ENDED