FreeBSD/Linux Kernel Cross Reference
sys/vm/vm_page.h

     /*
      * 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_page.h     8.2 (Berkeley) 12/13/93
     *
     *
     * Copyright (c) 1987, 1990 Carnegie-Mellon University.
     * All rights reserved.
     *
     * Authors: Avadis Tevanian, Jr., Michael Wayne Young
     *
     * 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.
     *
     * $FreeBSD$
     */
    
    /*
     *      Resident memory system definitions.
     */
    
    #ifndef _VM_PAGE_
    #define _VM_PAGE_
    
    #if !defined(KLD_MODULE)
    #include "opt_vmpage.h"
    #endif
    
    #include <vm/pmap.h>
    #include <machine/atomic.h>
    
    /*
     *      Management of resident (logical) pages.
     *
     *      A small structure is kept for each resident
     *      page, indexed by page number.  Each structure
     *      is an element of several lists:
     *
     *              A hash table bucket used to quickly
     *              perform object/offset lookups
     *
     *              A list of all pages for a given object,
     *              so they can be quickly deactivated at
     *              time of deallocation.
     *
     *              An ordered list of pages due for pageout.
     *
     *      In addition, the structure contains the object
     *      and offset to which this page belongs (for pageout),
     *      and sundry status bits.
    *
    *      Fields in this structure are locked either by the lock on the
    *      object that the page belongs to (O) or by the lock on the page
    *      queues (P).
    *
    *      The 'valid' and 'dirty' fields are distinct.  A page may have dirty
    *      bits set without having associated valid bits set.  This is used by
    *      NFS to implement piecemeal writes.
    */
   
   TAILQ_HEAD(pglist, vm_page);
   
   struct vm_page {
           TAILQ_ENTRY(vm_page) pageq;     /* queue info for FIFO queue or free list (P) */
           struct vm_page  *hnext;         /* hash table link (O,P)        */
           TAILQ_ENTRY(vm_page) listq;     /* pages in same object (O)     */
   
           vm_object_t object;             /* which object am I in (O,P)*/
           vm_pindex_t pindex;             /* offset into object (O,P) */
           vm_paddr_t phys_addr;           /* physical address of page */
           struct md_page md;              /* machine dependant stuff */
           u_short queue;                  /* page queue index */
           u_short flags,                  /* see below */
                   pc;                     /* page color */
           u_short wire_count;             /* wired down maps refs (P) */
           short hold_count;               /* page hold count */
           u_char  act_count;              /* page usage count */
           u_char  busy;                   /* page busy count */
           /* NOTE that these must support one bit per DEV_BSIZE in a page!!! */
           /* so, on normal X86 kernels, they must be at least 8 bits wide */
   #if PAGE_SIZE == 4096
           u_char  valid;                  /* map of valid DEV_BSIZE chunks */
           u_char  dirty;                  /* map of dirty DEV_BSIZE chunks */
   #elif PAGE_SIZE == 8192
           u_short valid;                  /* map of valid DEV_BSIZE chunks */
           u_short dirty;                  /* map of dirty DEV_BSIZE chunks */
   #endif
   };
   
   /*
    * note: currently use SWAPBLK_NONE as an absolute value rather then 
    * a flag bit.
    */
   
   #define SWAPBLK_MASK    ((daddr_t)((u_daddr_t)-1 >> 1))         /* mask */
   #define SWAPBLK_NONE    ((daddr_t)((u_daddr_t)SWAPBLK_MASK + 1))/* flag */
   
   #if !defined(KLD_MODULE)
   
   /*
    * Page coloring parameters
    */
   /* Each of PQ_FREE, and PQ_CACHE have PQ_HASH_SIZE entries */
   
   /* Backward compatibility for existing PQ_*CACHE config options. */
   #if !defined(PQ_CACHESIZE)
   #if defined(PQ_HUGECACHE)
   #define PQ_CACHESIZE 1024
   #elif defined(PQ_LARGECACHE)
   #define PQ_CACHESIZE 512
   #elif defined(PQ_MEDIUMCACHE)
   #define PQ_CACHESIZE 256
   #elif defined(PQ_NORMALCACHE)
   #define PQ_CACHESIZE 64
   #elif defined(PQ_NOOPT)
   #define PQ_CACHESIZE 0
   #else
   #define PQ_CACHESIZE 128
   #endif
   #endif
   
   #if PQ_CACHESIZE >= 1024
   #define PQ_PRIME1 31    /* Prime number somewhat less than PQ_HASH_SIZE */
   #define PQ_PRIME2 23    /* Prime number somewhat less than PQ_HASH_SIZE */
   #define PQ_L2_SIZE 256  /* A number of colors opt for 1M cache */
   
   #elif PQ_CACHESIZE >= 512
   #define PQ_PRIME1 31    /* Prime number somewhat less than PQ_HASH_SIZE */
   #define PQ_PRIME2 23    /* Prime number somewhat less than PQ_HASH_SIZE */
   #define PQ_L2_SIZE 128  /* A number of colors opt for 512K cache */
   
   #elif PQ_CACHESIZE >= 256
   #define PQ_PRIME1 13    /* Prime number somewhat less than PQ_HASH_SIZE */
   #define PQ_PRIME2 7     /* Prime number somewhat less than PQ_HASH_SIZE */
   #define PQ_L2_SIZE 64   /* A number of colors opt for 256K cache */
   
   #elif PQ_CACHESIZE >= 128
   #define PQ_PRIME1 9     /* Produces a good PQ_L2_SIZE/3 + PQ_PRIME1 */
   #define PQ_PRIME2 5     /* Prime number somewhat less than PQ_HASH_SIZE */
   #define PQ_L2_SIZE 32   /* A number of colors opt for 128k cache */
   
   #elif PQ_CACHESIZE >= 64
   #define PQ_PRIME1 5     /* Prime number somewhat less than PQ_HASH_SIZE */
   #define PQ_PRIME2 3     /* Prime number somewhat less than PQ_HASH_SIZE */
   #define PQ_L2_SIZE 16   /* A reasonable number of colors (opt for 64K cache) */
   
   #else
   #define PQ_PRIME1 1     /* Disable page coloring. */
   #define PQ_PRIME2 1
   #define PQ_L2_SIZE 1
   
   #endif
   
   #define PQ_L2_MASK (PQ_L2_SIZE - 1)
   
   #define PQ_NONE 0
   #define PQ_FREE 1
   #define PQ_INACTIVE (1 + 1*PQ_L2_SIZE)
   #define PQ_ACTIVE (2 + 1*PQ_L2_SIZE)
   #define PQ_CACHE (3 + 1*PQ_L2_SIZE)
   #define PQ_HOLD  (3 + 2*PQ_L2_SIZE)
   #define PQ_COUNT (4 + 2*PQ_L2_SIZE)
   
   struct vpgqueues {
           struct pglist pl;
           int     *cnt;
           int     lcnt;
   };
   
   extern struct vpgqueues vm_page_queues[PQ_COUNT];
   
   #endif
   
   /*
    * These are the flags defined for vm_page.
    *
    * Note: PG_FILLED and PG_DIRTY are added for the filesystems.
    *
    * Note: PG_UNMANAGED (used by OBJT_PHYS) indicates that the page is
    *       not under PV management but otherwise should be treated as a
    *       normal page.  Pages not under PV management cannot be paged out
    *       via the object/vm_page_t because there is no knowledge of their
    *       pte mappings, nor can they be removed from their objects via 
    *       the object, and such pages are also not on any PQ queue.
    */
   #define PG_BUSY         0x0001          /* page is in transit (O) */
   #define PG_WANTED       0x0002          /* someone is waiting for page (O) */
   #define PG_WINATCFLS    0x0004          /* flush dirty page on inactive q */
   #define PG_FICTITIOUS   0x0008          /* physical page doesn't exist (O) */
   #define PG_WRITEABLE    0x0010          /* page is mapped writeable */
   #define PG_MAPPED       0x0020          /* page is mapped */
   #define PG_ZERO         0x0040          /* page is zeroed */
   #define PG_REFERENCED   0x0080          /* page has been referenced */
   #define PG_CLEANCHK     0x0100          /* page will be checked for cleaning */
   #define PG_SWAPINPROG   0x0200          /* swap I/O in progress on page      */
   #define PG_NOSYNC       0x0400          /* do not collect for syncer */
   #define PG_UNMANAGED    0x0800          /* No PV management for page */
   #define PG_MARKER       0x1000          /* special queue marker page */
   
   /*
    * Misc constants.
    */
   
   #define ACT_DECLINE             1
   #define ACT_ADVANCE             3
   #define ACT_INIT                5
   #define ACT_MAX                 64
   #define PFCLUSTER_BEHIND        3
   #define PFCLUSTER_AHEAD         3
   
   #ifdef _KERNEL
   /*
    * Each pageable resident page falls into one of four lists:
    *
    *      free
    *              Available for allocation now.
    *
    * The following are all LRU sorted:
    *
    *      cache
    *              Almost available for allocation. Still in an
    *              object, but clean and immediately freeable at
    *              non-interrupt times.
    *
    *      inactive
    *              Low activity, candidates for reclamation.
    *              This is the list of pages that should be
    *              paged out next.
    *
    *      active
    *              Pages that are "active" i.e. they have been
    *              recently referenced.
    *
    *      zero
    *              Pages that are really free and have been pre-zeroed
    *
    */
   
   extern int vm_page_zero_count;
   
   extern vm_page_t vm_page_array;         /* First resident page in table */
   extern int vm_page_array_size;          /* number of vm_page_t's */
   extern long first_page;                 /* first physical page number */
   
   #define VM_PAGE_TO_PHYS(entry)  ((entry)->phys_addr)
   
   #define PHYS_TO_VM_PAGE(pa) \
                   (&vm_page_array[atop(pa) - first_page ])
   
   /*
    *      Functions implemented as macros
    */
   
   static __inline void
   vm_page_flag_set(vm_page_t m, unsigned int bits)
   {
           atomic_set_short(&(m)->flags, bits);
   }
   
   static __inline void
   vm_page_flag_clear(vm_page_t m, unsigned int bits)
   {
           atomic_clear_short(&(m)->flags, bits);
   }
   
   #if 0
   static __inline void
   vm_page_assert_wait(vm_page_t m, int interruptible)
   {
           vm_page_flag_set(m, PG_WANTED);
           assert_wait((int) m, interruptible);
   }
   #endif
   
   static __inline void
   vm_page_busy(vm_page_t m)
   {
           KASSERT((m->flags & PG_BUSY) == 0, ("vm_page_busy: page already busy!!!"));
           vm_page_flag_set(m, PG_BUSY);
   }
   
   /*
    *      vm_page_flash:
    *
    *      wakeup anyone waiting for the page.
    */
   
   static __inline void
   vm_page_flash(vm_page_t m)
   {
           if (m->flags & PG_WANTED) {
                   vm_page_flag_clear(m, PG_WANTED);
                   wakeup(m);
           }
   }
   
   /*
    *      vm_page_wakeup:
    *
    *      clear the PG_BUSY flag and wakeup anyone waiting for the
    *      page.
    *
    */
   
   static __inline void
   vm_page_wakeup(vm_page_t m)
   {
           KASSERT(m->flags & PG_BUSY, ("vm_page_wakeup: page not busy!!!"));
           vm_page_flag_clear(m, PG_BUSY);
           vm_page_flash(m);
   }
   
   /*
    *
    *
    */
   
   static __inline void
   vm_page_io_start(vm_page_t m)
   {
           atomic_add_char(&(m)->busy, 1);
   }
   
   static __inline void
   vm_page_io_finish(vm_page_t m)
   {
           atomic_subtract_char(&m->busy, 1);
           if (m->busy == 0)
                   vm_page_flash(m);
   }
   
   
   #if PAGE_SIZE == 4096
   #define VM_PAGE_BITS_ALL 0xff
   #endif
   
   #if PAGE_SIZE == 8192
   #define VM_PAGE_BITS_ALL 0xffff
   #endif
   
   #define VM_ALLOC_NORMAL         0
   #define VM_ALLOC_INTERRUPT      1
   #define VM_ALLOC_SYSTEM         2
   #define VM_ALLOC_ZERO           3
   #define VM_ALLOC_RETRY          0x80
   
   void vm_page_unhold(vm_page_t mem);
   
   void vm_page_activate (vm_page_t);
   vm_page_t vm_page_alloc (vm_object_t, vm_pindex_t, int);
   vm_page_t vm_page_grab (vm_object_t, vm_pindex_t, int);
   void vm_page_cache (register vm_page_t);
   int vm_page_try_to_cache (vm_page_t);
   int vm_page_try_to_free (vm_page_t);
   void vm_page_dontneed (register vm_page_t);
   static __inline void vm_page_copy (vm_page_t, vm_page_t);
   static __inline void vm_page_free (vm_page_t);
   static __inline void vm_page_free_zero (vm_page_t);
   void vm_page_deactivate (vm_page_t);
   void vm_page_insert (vm_page_t, vm_object_t, vm_pindex_t);
   vm_page_t vm_page_lookup (vm_object_t, vm_pindex_t);
   void vm_page_remove (vm_page_t);
   void vm_page_rename (vm_page_t, vm_object_t, vm_pindex_t);
   vm_offset_t vm_page_startup (vm_offset_t, vm_offset_t, vm_offset_t);
   vm_page_t vm_add_new_page (vm_paddr_t pa);
   void vm_page_unmanage (vm_page_t);
   void vm_page_unwire (vm_page_t, int);
   void vm_page_wire (vm_page_t);
   void vm_page_unqueue (vm_page_t);
   void vm_page_unqueue_nowakeup (vm_page_t);
   void vm_page_set_validclean (vm_page_t, int, int);
   void vm_page_set_dirty (vm_page_t, int, int);
   void vm_page_clear_dirty (vm_page_t, int, int);
   void vm_page_set_invalid (vm_page_t, int, int);
   static __inline boolean_t vm_page_zero_fill (vm_page_t);
   int vm_page_is_valid (vm_page_t, int, int);
   void vm_page_test_dirty (vm_page_t);
   int vm_page_bits (int, int);
   vm_page_t _vm_page_list_find (int, int);
   #if 0
   int vm_page_sleep(vm_page_t m, char *msg, char *busy);
   int vm_page_asleep(vm_page_t m, char *msg, char *busy);
   #endif
   void vm_page_zero_invalid(vm_page_t m, boolean_t setvalid);
   void vm_page_free_toq(vm_page_t m);
   
   /*
    * Keep page from being freed by the page daemon
    * much of the same effect as wiring, except much lower
    * overhead and should be used only for *very* temporary
    * holding ("wiring").
    */
   static __inline void
   vm_page_hold(vm_page_t mem)
   {
           mem->hold_count++;
   }
   
   /*
    *      vm_page_protect:
    *
    *      Reduce the protection of a page.  This routine never raises the 
    *      protection and therefore can be safely called if the page is already
    *      at VM_PROT_NONE (it will be a NOP effectively ).
    */
   
   static __inline void
   vm_page_protect(vm_page_t mem, int prot)
   {
           if (prot == VM_PROT_NONE) {
                   if (mem->flags & (PG_WRITEABLE|PG_MAPPED)) {
                           pmap_page_protect(mem, VM_PROT_NONE);
                           vm_page_flag_clear(mem, PG_WRITEABLE|PG_MAPPED);
                   }
           } else if ((prot == VM_PROT_READ) && (mem->flags & PG_WRITEABLE)) {
                   pmap_page_protect(mem, VM_PROT_READ);
                   vm_page_flag_clear(mem, PG_WRITEABLE);
           }
   }
   
   /*
    *      vm_page_zero_fill:
    *
    *      Zero-fill the specified page.
    *      Written as a standard pagein routine, to
    *      be used by the zero-fill object.
    */
   static __inline boolean_t
   vm_page_zero_fill(m)
           vm_page_t m;
   {
           pmap_zero_page(VM_PAGE_TO_PHYS(m));
           return (TRUE);
   }
   
   /*
    *      vm_page_copy:
    *
    *      Copy one page to another
    */
   static __inline void
   vm_page_copy(src_m, dest_m)
           vm_page_t src_m;
           vm_page_t dest_m;
   {
           pmap_copy_page(VM_PAGE_TO_PHYS(src_m), VM_PAGE_TO_PHYS(dest_m));
           dest_m->valid = VM_PAGE_BITS_ALL;
   }
   
   /*
    *      vm_page_free:
    *
    *      Free a page
    *
    *      The clearing of PG_ZERO is a temporary safety until the code can be
    *      reviewed to determine that PG_ZERO is being properly cleared on
    *      write faults or maps.  PG_ZERO was previously cleared in 
    *      vm_page_alloc().
    */
   static __inline void
   vm_page_free(m)
           vm_page_t m;
   {
           vm_page_flag_clear(m, PG_ZERO);
           vm_page_free_toq(m);
   }
   
   /*
    *      vm_page_free_zero:
    *
    *      Free a page to the zerod-pages queue
    */
   static __inline void
   vm_page_free_zero(m)
           vm_page_t m;
   {
           vm_page_flag_set(m, PG_ZERO);
           vm_page_free_toq(m);
   }
   
   /*
    *      vm_page_sleep_busy:
    *
    *      Wait until page is no longer PG_BUSY or (if also_m_busy is TRUE)
    *      m->busy is zero.  Returns TRUE if it had to sleep ( including if 
    *      it almost had to sleep and made temporary spl*() mods), FALSE 
    *      otherwise.
    *
    *      This routine assumes that interrupts can only remove the busy
    *      status from a page, not set the busy status or change it from
    *      PG_BUSY to m->busy or vise versa (which would create a timing
    *      window).
    *
    *      Note that being an inline, this code will be well optimized.
    */
   
   static __inline int
   vm_page_sleep_busy(vm_page_t m, int also_m_busy, const char *msg)
   {
           if ((m->flags & PG_BUSY) || (also_m_busy && m->busy))  {
                   int s = splvm();
                   if ((m->flags & PG_BUSY) || (also_m_busy && m->busy)) {
                           /*
                            * Page is busy. Wait and retry.
                            */
                           vm_page_flag_set(m, PG_WANTED | PG_REFERENCED);
                           tsleep(m, PVM, msg, 0);
                   }
                   splx(s);
                   return(TRUE);
                   /* not reached */
           }
           return(FALSE);
   }
   
   /*
    *      vm_page_dirty:
    *
    *      make page all dirty
    */
   
   static __inline void
   vm_page_dirty(vm_page_t m)
   {
   #if !defined(KLD_MODULE)
           KASSERT(m->queue - m->pc != PQ_CACHE, ("vm_page_dirty: page in cache!"));
   #endif
           m->dirty = VM_PAGE_BITS_ALL;
   }
   
   /*
    *      vm_page_undirty:
    *
    *      Set page to not be dirty.  Note: does not clear pmap modify bits 
    */
   
   static __inline void
   vm_page_undirty(vm_page_t m)
   {
           m->dirty = 0;
   }
   
   #if !defined(KLD_MODULE)
   
   static __inline vm_page_t
   vm_page_list_find(int basequeue, int index, boolean_t prefer_zero)
   {
           vm_page_t m;
   
   #if PQ_L2_SIZE > 1
           if (prefer_zero) {
                   m = TAILQ_LAST(&vm_page_queues[basequeue+index].pl, pglist);
           } else {
                   m = TAILQ_FIRST(&vm_page_queues[basequeue+index].pl);
           }
           if (m == NULL)
                   m = _vm_page_list_find(basequeue, index);
   #else
           if (prefer_zero) {
                   m = TAILQ_LAST(&vm_page_queues[basequeue].pl, pglist);
           } else {
                   m = TAILQ_FIRST(&vm_page_queues[basequeue].pl);
           }
   #endif
           return(m);
   }
   
   #endif
   
   #endif                          /* _KERNEL */
   #endif                          /* !_VM_PAGE_ */

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