#ifndef THREADS_THREAD_H #define THREADS_THREAD_H #include #include #include #include #include #include "threads/synch.h" #include "threads/fixed-point.h" /* States in a thread's life cycle. */ enum thread_status { THREAD_RUNNING, /* Running thread. */ THREAD_READY, /* Not running but ready to run. */ THREAD_BLOCKED, /* Waiting for an event to trigger. */ THREAD_DYING /* About to be destroyed. */ }; /* Thread identifier type. You can redefine this to whatever type you like. */ typedef int tid_t; #define TID_ERROR ((tid_t) -1) /* Error value for tid_t. */ /* Thread priorities. */ #define PRI_MIN 0 /* Lowest priority. */ #define PRI_DEFAULT 31 /* Default priority. */ #define PRI_MAX 63 /* Highest priority. */ #define NICE_MIN -20 /* Lowest niceness. */ #define NICE_DEFAULT 0 /* Default niceness. */ #define NICE_MAX 20 /* Highest niceness. */ /* A process result, synchronised between parent and child. */ struct process_result { tid_t tid; /* The tid of the child process. */ int exit_status; /* The exit status of the child process. Initially set to -1, then to exit_status when child dies. */ struct lock lock; /* Lock the exit_status and sema. */ struct semaphore sema; /* Semaphore to signal the parent that the exit_status has been set. */ struct list_elem elem; /* List element for the parent's children list. */ }; /* A kernel thread or user process. Each thread structure is stored in its own 4 kB page. The thread structure itself sits at the very bottom of the page (at offset 0). The rest of the page is reserved for the thread's kernel stack, which grows downward from the top of the page (at offset 4 kB). Here's an illustration: 4 kB +---------------------------------+ | kernel stack | | | | | | | | V | | grows downward | | | | | | | | | | | | | | | | | +---------------------------------+ | magic | | : | | : | | name | | status | 0 kB +---------------------------------+ The upshot of this is twofold: 1. First, `struct thread' must not be allowed to grow too big. If it does, then there will not be enough room for the kernel stack. Our base `struct thread' is only a few bytes in size. It probably should stay well under 1 kB. 2. Second, kernel stacks must not be allowed to grow too large. If a stack overflows, it will corrupt the thread state. Thus, kernel functions should not allocate large structures or arrays as non-static local variables. Use dynamic allocation with malloc() or palloc_get_page() instead. The first symptom of either of these problems will probably be an assertion failure in thread_current(), which checks that the `magic' member of the running thread's `struct thread' is set to THREAD_MAGIC. Stack overflow will normally change this value, triggering the assertion. */ /* The `elem' member has a dual purpose. It can be an element in the run queue (thread.c), or it can be an element in a semaphore wait list (synch.c). It can be used these two ways only because they are mutually exclusive: only a thread in the ready state is on the run queue, whereas only a thread in the blocked state is on a semaphore wait list. */ struct thread { /* Owned by thread.c. */ tid_t tid; /* Thread identifier. */ enum thread_status status; /* Thread state. */ char name[16]; /* Name (for debugging purposes). */ uint8_t *stack; /* Saved stack pointer. */ int priority; /* Priority. */ struct list_elem allelem; /* List element for all threads list. */ /* Donation Related */ int base_priority; /* Base priority of the thread. */ struct list donors_list; /* List of threads that have donated to this thread. */ struct lock *waiting_lock; /* The lock that the current thread is waiting for. */ struct list_elem donor_elem; /* List element so that thread can be enlisted in other donors list. */ /* MLFQS items */ int nice; /* Nice value for this thread */ fp32_t recent_cpu; /* Amount of time this process received */ /* Process wait properties. */ struct process_result *result; /* Result of the process. */ struct list child_results; /* List of children's of this thread process results. */ struct file *exec_file; /* Thread's currently running file */ /* Shared between thread.c and synch.c. */ struct list_elem elem; /* List element. */ int exit_status; /* Exit Status: 0 = successful exit. */ #ifdef USERPROG /* Owned by userprog/process.c. */ uint32_t *pagedir; /* Page directory. */ struct hash open_files; /* Hash Table of FD -> Struct File */ #endif /* Owned by thread.c. */ unsigned magic; /* Detects stack overflow. */ }; /* If false (default), use round-robin scheduler. If true, use multi-level feedback queue scheduler. Controlled by kernel command-line option "mlfqs". */ extern bool thread_mlfqs; void thread_init (void); void thread_start (void); size_t threads_ready(void); void thread_tick (void); void thread_print_stats (void); typedef void thread_func (void *aux); tid_t thread_create (const char *name, int priority, thread_func *, void *); void thread_block (void); void thread_unblock (struct thread *); struct thread *thread_current (void); tid_t thread_tid (void); const char *thread_name (void); void thread_exit (void) NO_RETURN; void thread_yield (void); /* Performs some operation on thread t, given auxiliary data AUX. */ typedef void thread_action_func (struct thread *t, void *aux); void thread_foreach (thread_action_func *, void *); bool priority_more (const struct list_elem *a_, const struct list_elem *b_, void *aux UNUSED); int thread_get_priority (void); void thread_set_priority (int); void thread_recalculate_priority (void); int thread_get_nice (void); void thread_set_nice (int); int thread_get_recent_cpu (void); int thread_get_load_avg (void); void ready_list_reinsert (struct thread *t); #endif /* threads/thread.h */