uvm_glue.c

来自「基于组件方式开发操作系统的OSKIT源代码」· C语言 代码 · 共 625 行 · 第 1/2 页

	 * cpu_fork() copy and update the pcb, and make the child ready
	 * to run.  If this is a normal user fork, the child will exit
	 * directly to user mode via child_return() on its first time
	 * slice and will not return here.  If this is a kernel thread,
	 * the specified entry point will be executed.
	 */
	cpu_fork(p1, p2, stack, stacksize, func, arg);
}

/*
 * uvm_exit: exit a virtual address space
 *
 * - the process passed to us is a dead (pre-zombie) process; we
 *   are running on a different context now (the reaper).
 * - we must run in a separate thread because freeing the vmspace
 *   of the dead process may block.
 */
void
uvm_exit(p)
	struct proc *p;
{
	vaddr_t va = (vaddr_t)p->p_addr;

	uvmspace_free(p->p_vmspace);
	p->p_flag &= ~P_INMEM;
	uvm_fault_unwire(kernel_map, va, va + USPACE);
	uvm_km_free(kernel_map, va, USPACE);
	p->p_addr = NULL;
}

/*
 * uvm_init_limit: init per-process VM limits
 *
 * - called for process 0 and then inherited by all others.
 */
void
uvm_init_limits(p)
	struct proc *p;
{

	/*
	 * Set up the initial limits on process VM.  Set the maximum
	 * resident set size to be all of (reasonably) available memory.
	 * This causes any single, large process to start random page
	 * replacement once it fills memory.
	 */

	p->p_rlimit[RLIMIT_STACK].rlim_cur = DFLSSIZ;
	p->p_rlimit[RLIMIT_STACK].rlim_max = MAXSSIZ;
	p->p_rlimit[RLIMIT_DATA].rlim_cur = DFLDSIZ;
	p->p_rlimit[RLIMIT_DATA].rlim_max = MAXDSIZ;
	p->p_rlimit[RLIMIT_RSS].rlim_cur = ptoa(uvmexp.free);
}

#ifdef DEBUG
int	enableswap = 1;
int	swapdebug = 0;
#define	SDB_FOLLOW	1
#define SDB_SWAPIN	2
#define SDB_SWAPOUT	4
#endif

/*
 * uvm_swapin: swap in a process's u-area.
 */

void
uvm_swapin(p)
	struct proc *p;
{
	vaddr_t addr;
	int s;

	addr = (vaddr_t)p->p_addr;
	/* make P_INMEM true */
	uvm_fault_wire(kernel_map, addr, addr + USPACE,
	    VM_PROT_READ | VM_PROT_WRITE);

	/*
	 * Some architectures need to be notified when the user area has
	 * moved to new physical page(s) (e.g.  see mips/mips/vm_machdep.c).
	 */
	cpu_swapin(p);
	SCHED_LOCK(s);
	if (p->p_stat == SRUN)
		setrunqueue(p);
	p->p_flag |= P_INMEM;
	SCHED_UNLOCK(s);
	p->p_swtime = 0;
	++uvmexp.swapins;
}

/*
 * uvm_scheduler: process zero main loop
 *
 * - attempt to swapin every swaped-out, runnable process in order of
 *	priority.
 * - if not enough memory, wake the pagedaemon and let it clear space.
 */

void
uvm_scheduler()
{
	struct proc *p;
	int pri;
	struct proc *pp;
	int ppri;

loop:
#ifdef DEBUG
	while (!enableswap)
		tsleep(&proc0, PVM, "noswap", 0);
#endif
	pp = NULL;		/* process to choose */
	ppri = INT_MIN;	/* its priority */
	proclist_lock_read();
	LIST_FOREACH(p, &allproc, p_list) {

		/* is it a runnable swapped out process? */
		if (p->p_stat == SRUN && (p->p_flag & P_INMEM) == 0) {
			pri = p->p_swtime + p->p_slptime -
			    (p->p_nice - NZERO) * 8;
			if (pri > ppri) {   /* higher priority?  remember it. */
				pp = p;
				ppri = pri;
			}
		}
	}
	/*
	 * XXXSMP: possible unlock/sleep race between here and the
	 * "scheduler" tsleep below..
	 */
	proclist_unlock_read();

#ifdef DEBUG
	if (swapdebug & SDB_FOLLOW)
		printf("scheduler: running, procp %p pri %d\n", pp, ppri);
#endif
	/*
	 * Nothing to do, back to sleep
	 */
	if ((p = pp) == NULL) {
		tsleep(&proc0, PVM, "scheduler", 0);
		goto loop;
	}

	/*
	 * we have found swapped out process which we would like to bring
	 * back in.
	 *
	 * XXX: this part is really bogus cuz we could deadlock on memory
	 * despite our feeble check
	 */
	if (uvmexp.free > atop(USPACE)) {
#ifdef DEBUG
		if (swapdebug & SDB_SWAPIN)
			printf("swapin: pid %d(%s)@%p, pri %d free %d\n",
	     p->p_pid, p->p_comm, p->p_addr, ppri, uvmexp.free);
#endif
		uvm_swapin(p);
		goto loop;
	}
	/*
	 * not enough memory, jab the pageout daemon and wait til the coast
	 * is clear
	 */
#ifdef DEBUG
	if (swapdebug & SDB_FOLLOW)
		printf("scheduler: no room for pid %d(%s), free %d\n",
	   p->p_pid, p->p_comm, uvmexp.free);
#endif
	uvm_wait("schedpwait");
#ifdef DEBUG
	if (swapdebug & SDB_FOLLOW)
		printf("scheduler: room again, free %d\n", uvmexp.free);
#endif
	goto loop;
}

/*
 * swappable: is process "p" swappable?
 */

#define	swappable(p)							\
	(((p)->p_flag & (P_SYSTEM | P_INMEM | P_WEXIT)) == P_INMEM &&	\
	 (p)->p_holdcnt == 0)

/*
 * swapout_threads: find threads that can be swapped and unwire their
 *	u-areas.
 *
 * - called by the pagedaemon
 * - try and swap at least one processs
 * - processes that are sleeping or stopped for maxslp or more seconds
 *   are swapped... otherwise the longest-sleeping or stopped process
 *   is swapped, otherwise the longest resident process...
 */
void
uvm_swapout_threads()
{
	struct proc *p;
	struct proc *outp, *outp2;
	int outpri, outpri2;
	int didswap = 0;
	extern int maxslp; 
	/* XXXCDC: should move off to uvmexp. or uvm., also in uvm_meter */

#ifdef DEBUG
	if (!enableswap)
		return;
#endif

	/*
	 * outp/outpri  : stop/sleep process with largest sleeptime < maxslp
	 * outp2/outpri2: the longest resident process (its swap time)
	 */
	outp = outp2 = NULL;
	outpri = outpri2 = 0;
	proclist_lock_read();
	LIST_FOREACH(p, &allproc, p_list) {
		if (!swappable(p))
			continue;
		switch (p->p_stat) {
		case SRUN:
		case SONPROC:
			if (p->p_swtime > outpri2) {
				outp2 = p;
				outpri2 = p->p_swtime;
			}
			continue;
			
		case SSLEEP:
		case SSTOP:
			if (p->p_slptime >= maxslp) {
				uvm_swapout(p);
				didswap++;
			} else if (p->p_slptime > outpri) {
				outp = p;
				outpri = p->p_slptime;
			}
			continue;
		}
	}
	proclist_unlock_read();

	/*
	 * If we didn't get rid of any real duds, toss out the next most
	 * likely sleeping/stopped or running candidate.  We only do this
	 * if we are real low on memory since we don't gain much by doing
	 * it (USPACE bytes).
	 */
	if (didswap == 0 && uvmexp.free <= atop(round_page(USPACE))) {
		if ((p = outp) == NULL)
			p = outp2;
#ifdef DEBUG
		if (swapdebug & SDB_SWAPOUT)
			printf("swapout_threads: no duds, try procp %p\n", p);
#endif
		if (p)
			uvm_swapout(p);
	}
	pmap_update();
}

/*
 * uvm_swapout: swap out process "p"
 *
 * - currently "swapout" means "unwire U-area" and "pmap_collect()" 
 *   the pmap.
 * - XXXCDC: should deactivate all process' private anonymous memory
 */

static void
uvm_swapout(p)
	struct proc *p;
{
	vaddr_t addr;
	int s;

#ifdef DEBUG
	if (swapdebug & SDB_SWAPOUT)
		printf("swapout: pid %d(%s)@%p, stat %x pri %d free %d\n",
	   p->p_pid, p->p_comm, p->p_addr, p->p_stat,
	   p->p_slptime, uvmexp.free);
#endif

	/*
	 * Do any machine-specific actions necessary before swapout.
	 * This can include saving floating point state, etc.
	 */
	cpu_swapout(p);

	/*
	 * Mark it as (potentially) swapped out.
	 */
	SCHED_LOCK(s);
	p->p_flag &= ~P_INMEM;
	if (p->p_stat == SRUN)
		remrunqueue(p);
	SCHED_UNLOCK(s);
	p->p_swtime = 0;
	++uvmexp.swapouts;

	/*
	 * Unwire the to-be-swapped process's user struct and kernel stack.
	 */
	addr = (vaddr_t)p->p_addr;
	uvm_fault_unwire(kernel_map, addr, addr + USPACE); /* !P_INMEM */
	pmap_collect(vm_map_pmap(&p->p_vmspace->vm_map));
}