FreeBSD/Linux Kernel Cross Reference
sys/vm/vm_glue.c

     /*
      * Copyright (c) 1991, 1993
      *      The Regents of the University of California.  All rights reserved.
      *
      * This code is derived from software contributed to Berkeley by
      * The Mach Operating System project at Carnegie-Mellon University.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      from: @(#)vm_glue.c     8.6 (Berkeley) 1/5/94
     *
     *
     * Copyright (c) 1987, 1990 Carnegie-Mellon University.
     * All rights reserved.
     *
     * Permission to use, copy, modify and distribute this software and
     * its documentation is hereby granted, provided that both the copyright
     * notice and this permission notice appear in all copies of the
     * software, derivative works or modified versions, and any portions
     * thereof, and that both notices appear in supporting documentation.
     *
     * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
     * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
     * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
     *
     * Carnegie Mellon requests users of this software to return to
     *
     *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
     *  School of Computer Science
     *  Carnegie Mellon University
     *  Pittsburgh PA 15213-3890
     *
     * any improvements or extensions that they make and grant Carnegie the
     * rights to redistribute these changes.
     *
     * $FreeBSD: src/sys/vm/vm_glue.c,v 1.55.2.4 1999/09/05 08:24:24 peter Exp $
     */
    
    #include "opt_rlimit.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/proc.h>
    #include <sys/resourcevar.h>
    #include <sys/buf.h>
    #include <sys/shm.h>
    #include <sys/vmmeter.h>
    
    #include <sys/kernel.h>
    #include <sys/dkstat.h>
    
    #include <vm/vm.h>
    #include <vm/vm_param.h>
    #include <vm/vm_inherit.h>
    #include <vm/vm_prot.h>
    #include <vm/lock.h>
    #include <vm/pmap.h>
    #include <vm/vm_map.h>
    #include <vm/vm_page.h>
    #include <vm/vm_pageout.h>
    #include <vm/vm_kern.h>
    #include <vm/vm_extern.h>
    #include <vm/vm_object.h>
    #include <vm/vm_pager.h>
    
    #include <sys/user.h>
    
    /*
     * System initialization
     *
     * Note: proc0 from proc.h
     */
    
   static void vm_init_limits __P((void *));
   SYSINIT(vm_limits, SI_SUB_VM_CONF, SI_ORDER_FIRST, vm_init_limits, &proc0)
   
   /*
    * THIS MUST BE THE LAST INITIALIZATION ITEM!!!
    *
    * Note: run scheduling should be divorced from the vm system.
    */
   static void scheduler __P((void *));
   SYSINIT(scheduler, SI_SUB_RUN_SCHEDULER, SI_ORDER_FIRST, scheduler, NULL)
   
   
   static void swapout __P((struct proc *));
   
   extern char kstack[];
   
   /* vm_map_t upages_map; */
   
   int
   kernacc(addr, len, rw)
           caddr_t addr;
           int len, rw;
   {
           boolean_t rv;
           vm_offset_t saddr, eaddr;
           vm_prot_t prot = rw == B_READ ? VM_PROT_READ : VM_PROT_WRITE;
   
           saddr = trunc_page(addr);
           eaddr = round_page(addr + len);
           vm_map_lock_read(kernel_map);
           rv = vm_map_check_protection(kernel_map, saddr, eaddr, prot);
           vm_map_unlock_read(kernel_map);
           return (rv == TRUE);
   }
   
   int
   useracc(addr, len, rw)
           caddr_t addr;
           int len, rw;
   {
           boolean_t rv;
           vm_prot_t prot = rw == B_READ ? VM_PROT_READ : VM_PROT_WRITE;
           vm_map_t map;
           vm_map_entry_t save_hint;
   
           /*
            * XXX - check separately to disallow access to user area and user
            * page tables - they are in the map.
            *
            * XXX - VM_MAXUSER_ADDRESS is an end address, not a max.  It was once
            * only used (as an end address) in trap.c.  Use it as an end address
            * here too.  This bogusness has spread.  I just fixed where it was
            * used as a max in vm_mmap.c.
            */
           if ((vm_offset_t) addr + len > /* XXX */ VM_MAXUSER_ADDRESS
               || (vm_offset_t) addr + len < (vm_offset_t) addr) {
                   return (FALSE);
           }
           map = &curproc->p_vmspace->vm_map;
           vm_map_lock_read(map);
           /*
            * We save the map hint, and restore it.  Useracc appears to distort
            * the map hint unnecessarily.
            */
           save_hint = map->hint;
           rv = vm_map_check_protection(map,
               trunc_page(addr), round_page(addr + len), prot);
           map->hint = save_hint;
           vm_map_unlock_read(map);
           
           return (rv == TRUE);
   }
   
   void
   vslock(addr, len)
           caddr_t addr;
           u_int len;
   {
           vm_map_pageable(&curproc->p_vmspace->vm_map, trunc_page(addr),
               round_page(addr + len), FALSE);
   }
   
   void
   vsunlock(addr, len, dirtied)
           caddr_t addr;
           u_int len;
           int dirtied;
   {
   #ifdef  lint
           dirtied++;
   #endif  /* lint */
           vm_map_pageable(&curproc->p_vmspace->vm_map, trunc_page(addr),
               round_page(addr + len), TRUE);
   }
   
   /*
    * Implement fork's actions on an address space.
    * Here we arrange for the address space to be copied or referenced,
    * allocate a user struct (pcb and kernel stack), then call the
    * machine-dependent layer to fill those in and make the new process
    * ready to run.
    * NOTE: the kernel stack may be at a different location in the child
    * process, and thus addresses of automatic variables may be invalid
    * after cpu_fork returns in the child process.  We do nothing here
    * after cpu_fork returns.
    */
   int
   vm_fork(p1, p2)
           register struct proc *p1, *p2;
   {
           register struct user *up;
           int i;
           pmap_t pvp;
           vm_object_t upobj;
   
           while ((cnt.v_free_count + cnt.v_cache_count) < cnt.v_free_min) {
                   VM_WAIT;
           }
   
           p2->p_vmspace = vmspace_fork(p1->p_vmspace);
   
           if (p1->p_vmspace->vm_shm)
                   shmfork(p1, p2);
   
           pmap_new_proc(p2);
   
           up = p2->p_addr;
   
           /*
            * p_stats and p_sigacts currently point at fields in the user struct
            * but not at &u, instead at p_addr. Copy p_sigacts and parts of
            * p_stats; zero the rest of p_stats (statistics).
            */
           p2->p_stats = &up->u_stats;
           p2->p_sigacts = &up->u_sigacts;
           up->u_sigacts = *p1->p_sigacts;
           bzero(&up->u_stats.pstat_startzero,
               (unsigned) ((caddr_t) &up->u_stats.pstat_endzero -
                   (caddr_t) &up->u_stats.pstat_startzero));
           bcopy(&p1->p_stats->pstat_startcopy, &up->u_stats.pstat_startcopy,
               ((caddr_t) &up->u_stats.pstat_endcopy -
                   (caddr_t) &up->u_stats.pstat_startcopy));
   
   
           /*
            * cpu_fork will copy and update the kernel stack and pcb, and make
            * the child ready to run.  It marks the child so that it can return
            * differently than the parent. It returns twice, once in the parent
            * process and once in the child.
            */
           return (cpu_fork(p1, p2));
   }
   
   /*
    * Set default limits for VM system.
    * Called for proc 0, and then inherited by all others.
    *
    * XXX should probably act directly on proc0.
    */
   static void
   vm_init_limits(udata)
           void *udata;
   {
           register struct proc *p = udata;
           int rss_limit;
   
           /*
            * Set up the initial limits on process VM. Set the maximum resident
            * set size to be half of (reasonably) available memory.  Since this
            * is a soft limit, it comes into effect only when the system is out
            * of memory - half of main memory helps to favor smaller processes,
            * and reduces thrashing of the object cache.
            */
           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;
           /* limit the limit to no less than 2MB */
           rss_limit = max(cnt.v_free_count, 512);
           p->p_rlimit[RLIMIT_RSS].rlim_cur = ptoa(rss_limit);
           p->p_rlimit[RLIMIT_RSS].rlim_max = RLIM_INFINITY;
   }
   
   void
   faultin(p)
           struct proc *p;
   {
           vm_offset_t i;
           int s;
   
           if ((p->p_flag & P_INMEM) == 0) {
   
                   ++p->p_lock;
   
                   pmap_swapin_proc(p);
   
                   s = splhigh();
   
                   if (p->p_stat == SRUN)
                           setrunqueue(p);
   
                   p->p_flag |= P_INMEM;
   
                   /* undo the effect of setting SLOCK above */
                   --p->p_lock;
                   splx(s);
   
           }
   }
   
   /*
    * This swapin algorithm attempts to swap-in processes only if there
    * is enough space for them.  Of course, if a process waits for a long
    * time, it will be swapped in anyway.
    */
   /* ARGSUSED*/
   static void
   scheduler(dummy)
           void *dummy;
   {
           register struct proc *p;
           register int pri;
           struct proc *pp;
           int ppri;
   
   loop:
           while ((cnt.v_free_count + cnt.v_cache_count) < cnt.v_free_min) {
                   VM_WAIT;
           }
   
           pp = NULL;
           ppri = INT_MIN;
           for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
                   if (p->p_stat == SRUN &&
                           (p->p_flag & (P_INMEM | P_SWAPPING)) == 0) {
                           int mempri;
   
                           pri = p->p_swtime + p->p_slptime;
                           if ((p->p_flag & P_SWAPINREQ) == 0) {
                                   pri -= p->p_nice * 8;
                           }
                           mempri = pri > 0 ? pri : 0;
                           /*
                            * if this process is higher priority and there is
                            * enough space, then select this process instead of
                            * the previous selection.
                            */
                           if (pri > ppri) {
                                   pp = p;
                                   ppri = pri;
                           }
                   }
           }
   
           /*
            * Nothing to do, back to sleep.
            */
           if ((p = pp) == NULL) {
                   tsleep(&proc0, PVM, "sched", 0);
                   goto loop;
           }
           p->p_flag &= ~P_SWAPINREQ;
   
           /*
            * We would like to bring someone in. (only if there is space).
            */
           faultin(p);
           p->p_swtime = 0;
           goto loop;
   }
   
   #ifndef NO_SWAPPING
   
   #define swappable(p) \
           (((p)->p_lock == 0) && \
                   ((p)->p_flag & (P_TRACED|P_NOSWAP|P_SYSTEM|P_INMEM|P_WEXIT|P_PHYSIO|P_SWAPPING)) == P_INMEM)
   
   /*
    * Swapout is driven by the pageout daemon.  Very simple, we find eligible
    * procs and unwire their u-areas.  We try to always "swap" at least one
    * process in case we need the room for a swapin.
    * If any procs have been sleeping/stopped for at least maxslp seconds,
    * they are swapped.  Else, we swap the longest-sleeping or stopped process,
    * if any, otherwise the longest-resident process.
    */
   void
   swapout_procs()
   {
           register struct proc *p;
           struct proc *outp, *outp2;
           int outpri, outpri2;
           int didswap = 0;
   
           outp = outp2 = NULL;
           outpri = outpri2 = INT_MIN;
   retry:
           for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
                   struct vmspace *vm;
                   if (!swappable(p))
                           continue;
   
                   vm = p->p_vmspace;
   
                   switch (p->p_stat) {
                   default:
                           continue;
   
                   case SSLEEP:
                   case SSTOP:
                           /*
                            * do not swapout a realtime process
                            */
                           if (p->p_rtprio.type == RTP_PRIO_REALTIME)
                                   continue;
   
                           /*
                            * do not swapout a process waiting on a critical
                            * event of some kind
                            */
                           if (((p->p_priority & 0x7f) < PSOCK) ||
                                   (p->p_slptime <= 10))
                                   continue;
   
                           ++vm->vm_refcnt;
                           vm_map_reference(&vm->vm_map);
                           /*
                            * do not swapout a process that is waiting for VM
                            * datastructures there is a possible deadlock.
                            */
                           if (!lock_try_write(&vm->vm_map.lock)) {
                                   vm_map_deallocate(&vm->vm_map);
                                   vmspace_free(vm);
                                   continue;
                           }
                           vm_map_unlock(&vm->vm_map);
                           /*
                            * If the process has been asleep for awhile and had
                            * most of its pages taken away already, swap it out.
                            */
                           swapout(p);
                           vm_map_deallocate(&vm->vm_map);
                           vmspace_free(vm);
                           didswap++;
                           goto retry;
                   }
           }
           /*
            * If we swapped something out, and another process needed memory,
            * then wakeup the sched process.
            */
           if (didswap)
                   wakeup(&proc0);
   }
   
   static void
   swapout(p)
           register struct proc *p;
   {
           pmap_t pmap = &p->p_vmspace->vm_pmap;
           int i;
   
   #if defined(SWAP_DEBUG)
           printf("swapping out %d\n", p->p_pid);
   #endif
           ++p->p_stats->p_ru.ru_nswap;
           /*
            * remember the process resident count
            */
           p->p_vmspace->vm_swrss =
               p->p_vmspace->vm_pmap.pm_stats.resident_count;
   
           (void) splhigh();
           p->p_flag &= ~P_INMEM;
           p->p_flag |= P_SWAPPING;
           if (p->p_stat == SRUN)
                   remrq(p);
           (void) spl0();
   
           pmap_swapout_proc(p);
   
           p->p_flag &= ~P_SWAPPING;
           p->p_swtime = 0;
   }
   #endif /* !NO_SWAPPING */

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