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uvm_glue.c revision 1.36
      1 /*	$NetBSD: uvm_glue.c,v 1.36 2000/06/18 05:20:27 simonb Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1997 Charles D. Cranor and Washington University.
      5  * Copyright (c) 1991, 1993, The Regents of the University of California.
      6  *
      7  * All rights reserved.
      8  *
      9  * This code is derived from software contributed to Berkeley by
     10  * The Mach Operating System project at Carnegie-Mellon University.
     11  *
     12  * Redistribution and use in source and binary forms, with or without
     13  * modification, are permitted provided that the following conditions
     14  * are met:
     15  * 1. Redistributions of source code must retain the above copyright
     16  *    notice, this list of conditions and the following disclaimer.
     17  * 2. Redistributions in binary form must reproduce the above copyright
     18  *    notice, this list of conditions and the following disclaimer in the
     19  *    documentation and/or other materials provided with the distribution.
     20  * 3. All advertising materials mentioning features or use of this software
     21  *    must display the following acknowledgement:
     22  *	This product includes software developed by Charles D. Cranor,
     23  *      Washington University, the University of California, Berkeley and
     24  *      its contributors.
     25  * 4. Neither the name of the University nor the names of its contributors
     26  *    may be used to endorse or promote products derived from this software
     27  *    without specific prior written permission.
     28  *
     29  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     30  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     31  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     32  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     33  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     34  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     35  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     36  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     37  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     38  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     39  * SUCH DAMAGE.
     40  *
     41  *	@(#)vm_glue.c	8.6 (Berkeley) 1/5/94
     42  * from: Id: uvm_glue.c,v 1.1.2.8 1998/02/07 01:16:54 chs Exp
     43  *
     44  *
     45  * Copyright (c) 1987, 1990 Carnegie-Mellon University.
     46  * All rights reserved.
     47  *
     48  * Permission to use, copy, modify and distribute this software and
     49  * its documentation is hereby granted, provided that both the copyright
     50  * notice and this permission notice appear in all copies of the
     51  * software, derivative works or modified versions, and any portions
     52  * thereof, and that both notices appear in supporting documentation.
     53  *
     54  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
     55  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
     56  * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
     57  *
     58  * Carnegie Mellon requests users of this software to return to
     59  *
     60  *  Software Distribution Coordinator  or  Software.Distribution (at) CS.CMU.EDU
     61  *  School of Computer Science
     62  *  Carnegie Mellon University
     63  *  Pittsburgh PA 15213-3890
     64  *
     65  * any improvements or extensions that they make and grant Carnegie the
     66  * rights to redistribute these changes.
     67  */
     68 
     69 #include "opt_uvmhist.h"
     70 #include "opt_sysv.h"
     71 
     72 /*
     73  * uvm_glue.c: glue functions
     74  */
     75 
     76 #include <sys/param.h>
     77 #include <sys/systm.h>
     78 #include <sys/proc.h>
     79 #include <sys/resourcevar.h>
     80 #include <sys/buf.h>
     81 #include <sys/user.h>
     82 #ifdef SYSVSHM
     83 #include <sys/shm.h>
     84 #endif
     85 
     86 #include <vm/vm.h>
     87 #include <vm/vm_page.h>
     88 #include <vm/vm_kern.h>
     89 
     90 #include <uvm/uvm.h>
     91 
     92 #include <machine/cpu.h>
     93 
     94 /*
     95  * local prototypes
     96  */
     97 
     98 static void uvm_swapout __P((struct proc *));
     99 
    100 /*
    101  * XXXCDC: do these really belong here?
    102  */
    103 
    104 unsigned maxdmap = MAXDSIZ;	/* kern_resource.c: RLIMIT_DATA max */
    105 unsigned maxsmap = MAXSSIZ;	/* kern_resource.c: RLIMIT_STACK max */
    106 
    107 int readbuffers = 0;		/* allow KGDB to read kern buffer pool */
    108 				/* XXX: see uvm_kernacc */
    109 
    110 
    111 /*
    112  * uvm_kernacc: can the kernel access a region of memory
    113  *
    114  * - called from malloc [DIAGNOSTIC], and /dev/kmem driver (mem.c)
    115  */
    116 
    117 boolean_t
    118 uvm_kernacc(addr, len, rw)
    119 	caddr_t addr;
    120 	size_t len;
    121 	int rw;
    122 {
    123 	boolean_t rv;
    124 	vaddr_t saddr, eaddr;
    125 	vm_prot_t prot = rw == B_READ ? VM_PROT_READ : VM_PROT_WRITE;
    126 
    127 	saddr = trunc_page((vaddr_t)addr);
    128 	eaddr = round_page((vaddr_t)addr+len);
    129 	vm_map_lock_read(kernel_map);
    130 	rv = uvm_map_checkprot(kernel_map, saddr, eaddr, prot);
    131 	vm_map_unlock_read(kernel_map);
    132 
    133 	/*
    134 	 * XXX there are still some things (e.g. the buffer cache) that
    135 	 * are managed behind the VM system's back so even though an
    136 	 * address is accessible in the mind of the VM system, there may
    137 	 * not be physical pages where the VM thinks there is.  This can
    138 	 * lead to bogus allocation of pages in the kernel address space
    139 	 * or worse, inconsistencies at the pmap level.  We only worry
    140 	 * about the buffer cache for now.
    141 	 */
    142 	if (!readbuffers && rv && (eaddr > (vaddr_t)buffers &&
    143 			     saddr < (vaddr_t)buffers + MAXBSIZE * nbuf))
    144 		rv = FALSE;
    145 	return(rv);
    146 }
    147 
    148 /*
    149  * uvm_useracc: can the user access it?
    150  *
    151  * - called from physio() and sys___sysctl().
    152  */
    153 
    154 boolean_t
    155 uvm_useracc(addr, len, rw)
    156 	caddr_t addr;
    157 	size_t len;
    158 	int rw;
    159 {
    160 	vm_map_t map;
    161 	boolean_t rv;
    162 	vm_prot_t prot = rw == B_READ ? VM_PROT_READ : VM_PROT_WRITE;
    163 
    164 	/* XXX curproc */
    165 	map = &curproc->p_vmspace->vm_map;
    166 
    167 	vm_map_lock_read(map);
    168 	rv = uvm_map_checkprot(map, trunc_page((vaddr_t)addr),
    169 	    round_page((vaddr_t)addr+len), prot);
    170 	vm_map_unlock_read(map);
    171 
    172 	return(rv);
    173 }
    174 
    175 #ifdef KGDB
    176 /*
    177  * Change protections on kernel pages from addr to addr+len
    178  * (presumably so debugger can plant a breakpoint).
    179  *
    180  * We force the protection change at the pmap level.  If we were
    181  * to use vm_map_protect a change to allow writing would be lazily-
    182  * applied meaning we would still take a protection fault, something
    183  * we really don't want to do.  It would also fragment the kernel
    184  * map unnecessarily.  We cannot use pmap_protect since it also won't
    185  * enforce a write-enable request.  Using pmap_enter is the only way
    186  * we can ensure the change takes place properly.
    187  */
    188 void
    189 uvm_chgkprot(addr, len, rw)
    190 	caddr_t addr;
    191 	size_t len;
    192 	int rw;
    193 {
    194 	vm_prot_t prot;
    195 	paddr_t pa;
    196 	vaddr_t sva, eva;
    197 
    198 	prot = rw == B_READ ? VM_PROT_READ : VM_PROT_READ|VM_PROT_WRITE;
    199 	eva = round_page((vaddr_t)addr + len);
    200 	for (sva = trunc_page((vaddr_t)addr); sva < eva; sva += PAGE_SIZE) {
    201 		/*
    202 		 * Extract physical address for the page.
    203 		 * We use a cheezy hack to differentiate physical
    204 		 * page 0 from an invalid mapping, not that it
    205 		 * really matters...
    206 		 */
    207 		if (pmap_extract(pmap_kernel(), sva, &pa) == FALSE)
    208 			panic("chgkprot: invalid page");
    209 		pmap_enter(pmap_kernel(), sva, pa, prot, PMAP_WIRED);
    210 	}
    211 }
    212 #endif
    213 
    214 /*
    215  * vslock: wire user memory for I/O
    216  *
    217  * - called from physio and sys___sysctl
    218  * - XXXCDC: consider nuking this (or making it a macro?)
    219  */
    220 
    221 int
    222 uvm_vslock(p, addr, len, access_type)
    223 	struct proc *p;
    224 	caddr_t	addr;
    225 	size_t	len;
    226 	vm_prot_t access_type;
    227 {
    228 	vm_map_t map;
    229 	vaddr_t start, end;
    230 	int rv;
    231 
    232 	map = &p->p_vmspace->vm_map;
    233 	start = trunc_page((vaddr_t)addr);
    234 	end = round_page((vaddr_t)addr + len);
    235 
    236 	rv = uvm_fault_wire(map, start, end, access_type);
    237 
    238 	return (rv);
    239 }
    240 
    241 /*
    242  * vslock: wire user memory for I/O
    243  *
    244  * - called from physio and sys___sysctl
    245  * - XXXCDC: consider nuking this (or making it a macro?)
    246  */
    247 
    248 void
    249 uvm_vsunlock(p, addr, len)
    250 	struct proc *p;
    251 	caddr_t	addr;
    252 	size_t	len;
    253 {
    254 	uvm_fault_unwire(&p->p_vmspace->vm_map, trunc_page((vaddr_t)addr),
    255 		round_page((vaddr_t)addr+len));
    256 }
    257 
    258 /*
    259  * uvm_fork: fork a virtual address space
    260  *
    261  * - the address space is copied as per parent map's inherit values
    262  * - a new "user" structure is allocated for the child process
    263  *	[filled in by MD layer...]
    264  * - if specified, the child gets a new user stack described by
    265  *	stack and stacksize
    266  * - NOTE: the kernel stack may be at a different location in the child
    267  *	process, and thus addresses of automatic variables may be invalid
    268  *	after cpu_fork returns in the child process.  We do nothing here
    269  *	after cpu_fork returns.
    270  * - XXXCDC: we need a way for this to return a failure value rather
    271  *   than just hang
    272  */
    273 void
    274 uvm_fork(p1, p2, shared, stack, stacksize, func, arg)
    275 	struct proc *p1, *p2;
    276 	boolean_t shared;
    277 	void *stack;
    278 	size_t stacksize;
    279 	void (*func) __P((void *));
    280 	void *arg;
    281 {
    282 	struct user *up = p2->p_addr;
    283 	int rv;
    284 
    285 	if (shared == TRUE)
    286 		uvmspace_share(p1, p2);			/* share vmspace */
    287 	else
    288 		p2->p_vmspace = uvmspace_fork(p1->p_vmspace); /* fork vmspace */
    289 
    290 	/*
    291 	 * Wire down the U-area for the process, which contains the PCB
    292 	 * and the kernel stack.  Wired state is stored in p->p_flag's
    293 	 * P_INMEM bit rather than in the vm_map_entry's wired count
    294 	 * to prevent kernel_map fragmentation.
    295 	 *
    296 	 * Note the kernel stack gets read/write accesses right off
    297 	 * the bat.
    298 	 */
    299 	rv = uvm_fault_wire(kernel_map, (vaddr_t)up,
    300 	    (vaddr_t)up + USPACE, VM_PROT_READ | VM_PROT_WRITE);
    301 	if (rv != KERN_SUCCESS)
    302 		panic("uvm_fork: uvm_fault_wire failed: %d", rv);
    303 
    304 	/*
    305 	 * p_stats currently points at a field in the user struct.  Copy
    306 	 * parts of p_stats, and zero out the rest.
    307 	 */
    308 	p2->p_stats = &up->u_stats;
    309 	memset(&up->u_stats.pstat_startzero, 0,
    310 	(unsigned) ((caddr_t)&up->u_stats.pstat_endzero -
    311 		    (caddr_t)&up->u_stats.pstat_startzero));
    312 	memcpy(&up->u_stats.pstat_startcopy, &p1->p_stats->pstat_startcopy,
    313 	((caddr_t)&up->u_stats.pstat_endcopy -
    314 	 (caddr_t)&up->u_stats.pstat_startcopy));
    315 
    316 	/*
    317 	 * cpu_fork() copy and update the pcb, and make the child ready
    318 	 * to run.  If this is a normal user fork, the child will exit
    319 	 * directly to user mode via child_return() on its first time
    320 	 * slice and will not return here.  If this is a kernel thread,
    321 	 * the specified entry point will be executed.
    322 	 */
    323 	cpu_fork(p1, p2, stack, stacksize, func, arg);
    324 }
    325 
    326 /*
    327  * uvm_exit: exit a virtual address space
    328  *
    329  * - the process passed to us is a dead (pre-zombie) process; we
    330  *   are running on a different context now (the reaper).
    331  * - we must run in a separate thread because freeing the vmspace
    332  *   of the dead process may block.
    333  */
    334 void
    335 uvm_exit(p)
    336 	struct proc *p;
    337 {
    338 
    339 	uvmspace_free(p->p_vmspace);
    340 	uvm_km_free(kernel_map, (vaddr_t)p->p_addr, USPACE);
    341 	p->p_addr = NULL;
    342 }
    343 
    344 /*
    345  * uvm_init_limit: init per-process VM limits
    346  *
    347  * - called for process 0 and then inherited by all others.
    348  */
    349 void
    350 uvm_init_limits(p)
    351 	struct proc *p;
    352 {
    353 
    354 	/*
    355 	 * Set up the initial limits on process VM.  Set the maximum
    356 	 * resident set size to be all of (reasonably) available memory.
    357 	 * This causes any single, large process to start random page
    358 	 * replacement once it fills memory.
    359 	 */
    360 
    361 	p->p_rlimit[RLIMIT_STACK].rlim_cur = DFLSSIZ;
    362 	p->p_rlimit[RLIMIT_STACK].rlim_max = MAXSSIZ;
    363 	p->p_rlimit[RLIMIT_DATA].rlim_cur = DFLDSIZ;
    364 	p->p_rlimit[RLIMIT_DATA].rlim_max = MAXDSIZ;
    365 	p->p_rlimit[RLIMIT_RSS].rlim_cur = ptoa(uvmexp.free);
    366 }
    367 
    368 #ifdef DEBUG
    369 int	enableswap = 1;
    370 int	swapdebug = 0;
    371 #define	SDB_FOLLOW	1
    372 #define SDB_SWAPIN	2
    373 #define SDB_SWAPOUT	4
    374 #endif
    375 
    376 /*
    377  * uvm_swapin: swap in a process's u-area.
    378  */
    379 
    380 void
    381 uvm_swapin(p)
    382 	struct proc *p;
    383 {
    384 	vaddr_t addr;
    385 	int s;
    386 
    387 	addr = (vaddr_t)p->p_addr;
    388 	/* make P_INMEM true */
    389 	uvm_fault_wire(kernel_map, addr, addr + USPACE,
    390 	    VM_PROT_READ | VM_PROT_WRITE);
    391 
    392 	/*
    393 	 * Some architectures need to be notified when the user area has
    394 	 * moved to new physical page(s) (e.g.  see mips/mips/vm_machdep.c).
    395 	 */
    396 	cpu_swapin(p);
    397 	s = splstatclock();
    398 	if (p->p_stat == SRUN)
    399 		setrunqueue(p);
    400 	p->p_flag |= P_INMEM;
    401 	splx(s);
    402 	p->p_swtime = 0;
    403 	++uvmexp.swapins;
    404 }
    405 
    406 /*
    407  * uvm_scheduler: process zero main loop
    408  *
    409  * - attempt to swapin every swaped-out, runnable process in order of
    410  *	priority.
    411  * - if not enough memory, wake the pagedaemon and let it clear space.
    412  */
    413 
    414 void
    415 uvm_scheduler()
    416 {
    417 	struct proc *p;
    418 	int pri;
    419 	struct proc *pp;
    420 	int ppri;
    421 	UVMHIST_FUNC("uvm_scheduler"); UVMHIST_CALLED(maphist);
    422 
    423 loop:
    424 #ifdef DEBUG
    425 	while (!enableswap)
    426 		tsleep((caddr_t)&proc0, PVM, "noswap", 0);
    427 #endif
    428 	pp = NULL;		/* process to choose */
    429 	ppri = INT_MIN;	/* its priority */
    430 	proclist_lock_read();
    431 	for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
    432 
    433 		/* is it a runnable swapped out process? */
    434 		if (p->p_stat == SRUN && (p->p_flag & P_INMEM) == 0) {
    435 			pri = p->p_swtime + p->p_slptime -
    436 			    (p->p_nice - NZERO) * 8;
    437 			if (pri > ppri) {   /* higher priority?  remember it. */
    438 				pp = p;
    439 				ppri = pri;
    440 			}
    441 		}
    442 	}
    443 	proclist_unlock_read();
    444 
    445 #ifdef DEBUG
    446 	if (swapdebug & SDB_FOLLOW)
    447 		printf("scheduler: running, procp %p pri %d\n", pp, ppri);
    448 #endif
    449 	/*
    450 	 * Nothing to do, back to sleep
    451 	 */
    452 	if ((p = pp) == NULL) {
    453 		tsleep((caddr_t)&proc0, PVM, "scheduler", 0);
    454 		goto loop;
    455 	}
    456 
    457 	/*
    458 	 * we have found swapped out process which we would like to bring
    459 	 * back in.
    460 	 *
    461 	 * XXX: this part is really bogus cuz we could deadlock on memory
    462 	 * despite our feeble check
    463 	 */
    464 	if (uvmexp.free > atop(USPACE)) {
    465 #ifdef DEBUG
    466 		if (swapdebug & SDB_SWAPIN)
    467 			printf("swapin: pid %d(%s)@%p, pri %d free %d\n",
    468 	     p->p_pid, p->p_comm, p->p_addr, ppri, uvmexp.free);
    469 #endif
    470 		uvm_swapin(p);
    471 		goto loop;
    472 	}
    473 	/*
    474 	 * not enough memory, jab the pageout daemon and wait til the coast
    475 	 * is clear
    476 	 */
    477 #ifdef DEBUG
    478 	if (swapdebug & SDB_FOLLOW)
    479 		printf("scheduler: no room for pid %d(%s), free %d\n",
    480 	   p->p_pid, p->p_comm, uvmexp.free);
    481 #endif
    482 	(void) splhigh();
    483 	uvm_wait("schedpwait");
    484 	(void) spl0();
    485 #ifdef DEBUG
    486 	if (swapdebug & SDB_FOLLOW)
    487 		printf("scheduler: room again, free %d\n", uvmexp.free);
    488 #endif
    489 	goto loop;
    490 }
    491 
    492 /*
    493  * swappable: is process "p" swappable?
    494  */
    495 
    496 #define	swappable(p)							\
    497 	(((p)->p_flag & (P_SYSTEM | P_INMEM | P_WEXIT)) == P_INMEM &&	\
    498 	 (p)->p_holdcnt == 0)
    499 
    500 /*
    501  * swapout_threads: find threads that can be swapped and unwire their
    502  *	u-areas.
    503  *
    504  * - called by the pagedaemon
    505  * - try and swap at least one processs
    506  * - processes that are sleeping or stopped for maxslp or more seconds
    507  *   are swapped... otherwise the longest-sleeping or stopped process
    508  *   is swapped, otherwise the longest resident process...
    509  */
    510 void
    511 uvm_swapout_threads()
    512 {
    513 	struct proc *p;
    514 	struct proc *outp, *outp2;
    515 	int outpri, outpri2;
    516 	int didswap = 0;
    517 	extern int maxslp;
    518 	/* XXXCDC: should move off to uvmexp. or uvm., also in uvm_meter */
    519 
    520 #ifdef DEBUG
    521 	if (!enableswap)
    522 		return;
    523 #endif
    524 
    525 	/*
    526 	 * outp/outpri  : stop/sleep process with largest sleeptime < maxslp
    527 	 * outp2/outpri2: the longest resident process (its swap time)
    528 	 */
    529 	outp = outp2 = NULL;
    530 	outpri = outpri2 = 0;
    531 	proclist_lock_read();
    532 	for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
    533 		if (!swappable(p))
    534 			continue;
    535 		switch (p->p_stat) {
    536 		case SRUN:
    537 		case SONPROC:
    538 			if (p->p_swtime > outpri2) {
    539 				outp2 = p;
    540 				outpri2 = p->p_swtime;
    541 			}
    542 			continue;
    543 
    544 		case SSLEEP:
    545 		case SSTOP:
    546 			if (p->p_slptime >= maxslp) {
    547 				uvm_swapout(p);			/* zap! */
    548 				didswap++;
    549 			} else if (p->p_slptime > outpri) {
    550 				outp = p;
    551 				outpri = p->p_slptime;
    552 			}
    553 			continue;
    554 		}
    555 	}
    556 	proclist_unlock_read();
    557 
    558 	/*
    559 	 * If we didn't get rid of any real duds, toss out the next most
    560 	 * likely sleeping/stopped or running candidate.  We only do this
    561 	 * if we are real low on memory since we don't gain much by doing
    562 	 * it (USPACE bytes).
    563 	 */
    564 	if (didswap == 0 && uvmexp.free <= atop(round_page(USPACE))) {
    565 		if ((p = outp) == NULL)
    566 			p = outp2;
    567 #ifdef DEBUG
    568 		if (swapdebug & SDB_SWAPOUT)
    569 			printf("swapout_threads: no duds, try procp %p\n", p);
    570 #endif
    571 		if (p)
    572 			uvm_swapout(p);
    573 	}
    574 }
    575 
    576 /*
    577  * uvm_swapout: swap out process "p"
    578  *
    579  * - currently "swapout" means "unwire U-area" and "pmap_collect()"
    580  *   the pmap.
    581  * - XXXCDC: should deactivate all process' private anonymous memory
    582  */
    583 
    584 static void
    585 uvm_swapout(p)
    586 	struct proc *p;
    587 {
    588 	vaddr_t addr;
    589 	int s;
    590 
    591 #ifdef DEBUG
    592 	if (swapdebug & SDB_SWAPOUT)
    593 		printf("swapout: pid %d(%s)@%p, stat %x pri %d free %d\n",
    594 	   p->p_pid, p->p_comm, p->p_addr, p->p_stat,
    595 	   p->p_slptime, uvmexp.free);
    596 #endif
    597 
    598 	/*
    599 	 * Do any machine-specific actions necessary before swapout.
    600 	 * This can include saving floating point state, etc.
    601 	 */
    602 	cpu_swapout(p);
    603 
    604 	/*
    605 	 * Unwire the to-be-swapped process's user struct and kernel stack.
    606 	 */
    607 	addr = (vaddr_t)p->p_addr;
    608 	uvm_fault_unwire(kernel_map, addr, addr + USPACE); /* !P_INMEM */
    609 	pmap_collect(vm_map_pmap(&p->p_vmspace->vm_map));
    610 
    611 	/*
    612 	 * Mark it as (potentially) swapped out.
    613 	 */
    614 	s = splstatclock();
    615 	p->p_flag &= ~P_INMEM;
    616 	if (p->p_stat == SRUN)
    617 		remrunqueue(p);
    618 	splx(s);
    619 	p->p_swtime = 0;
    620 	++uvmexp.swapouts;
    621 }
    622 
    623