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freebsd/sys/vm/vm_page.h
Alan Cox 4221e284a3 The VFS/BIO subsystem contained a number of hacks in order to optimize 
piecemeal, middle-of-file writes for NFS.  These hacks have caused no
end of trouble, especially when combined with mmap().  I've removed
them.  Instead, NFS will issue a read-before-write to fully
instantiate the struct buf containing the write.  NFS does, however,
optimize piecemeal appends to files.  For most common file operations,
you will not notice the difference.  The sole remaining fragment in
the VFS/BIO system is b_dirtyoff/end, which NFS uses to avoid cache
coherency issues with read-merge-write style operations.  NFS also
optimizes the write-covers-entire-buffer case by avoiding the
read-before-write.  There is quite a bit of room for further
optimization in these areas.

The VM system marks pages fully-valid (AKA vm_page_t->valid =
VM_PAGE_BITS_ALL) in several places, most noteably in vm_fault.  This
is not correct operation.  The vm_pager_get_pages() code is now
responsible for marking VM pages all-valid.  A number of VM helper
routines have been added to aid in zeroing-out the invalid portions of
a VM page prior to the page being marked all-valid.  This operation is
necessary to properly support mmap().  The zeroing occurs most often
when dealing with file-EOF situations.  Several bugs have been fixed
in the NFS subsystem, including bits handling file and directory EOF
situations and buf->b_flags consistancy issues relating to clearing
B_ERROR & B_INVAL, and handling B_DONE.

getblk() and allocbuf() have been rewritten.  B_CACHE operation is now
formally defined in comments and more straightforward in
implementation.  B_CACHE for VMIO buffers is based on the validity of
the backing store.  B_CACHE for non-VMIO buffers is based simply on
whether the buffer is B_INVAL or not (B_CACHE set if B_INVAL clear,
and vise-versa).  biodone() is now responsible for setting B_CACHE
when a successful read completes.  B_CACHE is also set when a bdwrite()
is initiated and when a bwrite() is initiated.  VFS VOP_BWRITE
routines (there are only two - nfs_bwrite() and bwrite()) are now
expected to set B_CACHE.  This means that bowrite() and bawrite() also
set B_CACHE indirectly.

There are a number of places in the code which were previously using
buf->b_bufsize (which is DEV_BSIZE aligned) when they should have
been using buf->b_bcount.  These have been fixed.  getblk() now clears
B_DONE on return because the rest of the system is so bad about
dealing with B_DONE.

Major fixes to NFS/TCP have been made.  A server-side bug could cause
requests to be lost by the server due to nfs_realign() overwriting
other rpc's in the same TCP mbuf chain.  The server's kernel must be
recompiled to get the benefit of the fixes.

Submitted by:	Matthew Dillon <dillon@apollo.backplane.com>
1999-05-02 23:57:16 +00:00

606 lines
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/*
* 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.
*
* $Id: vm_page.h,v 1.59 1999/04/05 19:38:29 julian Exp $
*/
/*
* 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_offset_t phys_addr; /* physical address of page */
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 SWAPBLK_NONE is a flag, basically the high 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 */
/* Define one of the following */
#if defined(PQ_HUGECACHE)
#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_PRIME3 17 /* Prime number somewhat less than PQ_HASH_SIZE */
#define PQ_L2_SIZE 256 /* A number of colors opt for 1M cache */
#endif
/* Define one of the following */
#if defined(PQ_LARGECACHE)
#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_PRIME3 17 /* Prime number somewhat less than PQ_HASH_SIZE */
#define PQ_L2_SIZE 128 /* A number of colors opt for 512K cache */
#endif
/*
* Use 'options PQ_NOOPT' to disable page coloring
*/
#if defined(PQ_NOOPT)
#define PQ_PRIME1 1
#define PQ_PRIME2 1
#define PQ_PRIME3 1
#define PQ_L2_SIZE 1
#endif
#if defined(PQ_NORMALCACHE)
#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_PRIME3 11 /* Prime number somewhat less than PQ_HASH_SIZE */
#define PQ_L2_SIZE 16 /* A reasonable number of colors (opt for 64K cache) */
#endif
#if defined(PQ_MEDIUMCACHE) || !defined(PQ_L2_SIZE)
#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_PRIME3 5 /* Prime number somewhat less than PQ_HASH_SIZE */
#define PQ_L2_SIZE 64 /* A number of colors opt for 256K cache */
#endif
#define PQ_L2_MASK (PQ_L2_SIZE - 1)
#define PQ_NONE 0
#define PQ_FREE 1
/* #define PQ_ZERO (1 + PQ_L2_SIZE) */
#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_COUNT (3 + 2*PQ_L2_SIZE)
extern struct vpgqueues {
struct pglist *pl;
int *cnt;
int *lcnt;
} 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.
*/
#define PG_BUSY 0x0001 /* page is in transit (O) */
#define PG_WANTED 0x0002 /* someone is waiting for page (O) */
#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 */
/*
* 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
*
*/
#if !defined(KLD_MODULE)
extern struct pglist vm_page_queue_free[PQ_L2_SIZE];/* memory free queue */
extern struct pglist vm_page_queue_active; /* active memory queue */
extern struct pglist vm_page_queue_inactive; /* inactive memory queue */
extern struct pglist vm_page_queue_cache[PQ_L2_SIZE];/* cache memory queue */
#endif
extern int vm_page_zero_count;
extern vm_page_t vm_page_array; /* First resident page in table */
extern long first_page; /* first physical page number */
/* ... represented in vm_page_array */
extern long last_page; /* last physical page number */
/* ... represented in vm_page_array */
/* [INCLUSIVE] */
extern vm_offset_t first_phys_addr; /* physical address for first_page */
extern vm_offset_t last_phys_addr; /* physical address for last_page */
#define VM_PAGE_TO_PHYS(entry) ((entry)->phys_addr)
#define IS_VM_PHYSADDR(pa) \
((pa) >= first_phys_addr && (pa) <= last_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_activate __P((vm_page_t));
vm_page_t vm_page_alloc __P((vm_object_t, vm_pindex_t, int));
vm_page_t vm_page_grab __P((vm_object_t, vm_pindex_t, int));
void vm_page_cache __P((register vm_page_t));
static __inline void vm_page_copy __P((vm_page_t, vm_page_t));
static __inline void vm_page_free __P((vm_page_t));
static __inline void vm_page_free_zero __P((vm_page_t));
void vm_page_destroy __P((vm_page_t));
void vm_page_deactivate __P((vm_page_t));
void vm_page_insert __P((vm_page_t, vm_object_t, vm_pindex_t));
vm_page_t vm_page_lookup __P((vm_object_t, vm_pindex_t));
void vm_page_remove __P((vm_page_t));
void vm_page_rename __P((vm_page_t, vm_object_t, vm_pindex_t));
vm_offset_t vm_page_startup __P((vm_offset_t, vm_offset_t, vm_offset_t));
void vm_page_unwire __P((vm_page_t, int));
void vm_page_wire __P((vm_page_t));
void vm_page_unqueue __P((vm_page_t));
void vm_page_unqueue_nowakeup __P((vm_page_t));
void vm_page_set_validclean __P((vm_page_t, int, int));
void vm_page_set_dirty __P((vm_page_t, int, int));
void vm_page_clear_dirty __P((vm_page_t, int, int));
void vm_page_set_invalid __P((vm_page_t, int, int));
static __inline boolean_t vm_page_zero_fill __P((vm_page_t));
int vm_page_is_valid __P((vm_page_t, int, int));
void vm_page_test_dirty __P((vm_page_t));
int vm_page_bits __P((int, int));
vm_page_t _vm_page_list_find __P((int, int));
int vm_page_queue_index __P((vm_offset_t, 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++;
}
static __inline void
vm_page_unhold(vm_page_t mem)
{
--mem->hold_count;
KASSERT(mem->hold_count >= 0, ("vm_page_unhold: hold count < 0!!!"));
}
/*
* 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(VM_PAGE_TO_PHYS(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(VM_PAGE_TO_PHYS(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);
}
#if !defined(KLD_MODULE)
/*
* vm_page_dirty:
*
* make page all dirty
*/
static __inline void
vm_page_dirty(vm_page_t m)
{
KASSERT(m->queue - m->pc != PQ_CACHE, ("vm_page_dirty: page in cache!"));
m->dirty = VM_PAGE_BITS_ALL;
}
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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