Processes

Processes

1    进程描述符

about 1.7k size, save in a list named task list.

include/linux/sched.h

struct task_struct {
	volatile long state;	/* -1 unrunnable, 0 runnable, >0 stopped */
	void *stack;
	atomic_t usage;
	unsigned int flags;	/* per process flags, defined below */
	unsigned int ptrace;

	int lock_depth;		/* BKL lock depth */

#ifdef CONFIG_SMP
#ifdef __ARCH_WANT_UNLOCKED_CTXSW
	int oncpu;
#endif
#endif

	int prio, static_prio, normal_prio;
	unsigned int rt_priority;
...

2    分配进程描述符

from 2.6 slab alloc task_struct.

arch/arm/include/asm/thread_info.h

struct thread_info {
	struct task_struct *task;	/* main task structure */
	struct exec_domain *exec_domain;/* execution domain */
	unsigned long flags;		/* thread_info flags (see TIF_*) */
	mm_segment_t addr_limit;	/* user-level address space limit */
	__u32 cpu;			/* current CPU */
	int preempt_count;		/* 0=premptable, <0=BUG; will also serve as bh-counter */
	struct restart_block restart_block;
};

若堆栈向下增长，只需在栈底创建一个struct thread_info，此时sp指向struct task_strcut *task(详见fork)。