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proc or any VM system structure will have to be rebuilt!!!
Much needed overhaul of the VM system. Included in this first round of
changes:
1) Improved pager interfaces: init, alloc, dealloc, getpages, putpages,
haspage, and sync operations are supported. The haspage interface now
provides information about clusterability. All pager routines now take
struct vm_object's instead of "pagers".
2) Improved data structures. In the previous paradigm, there is constant
confusion caused by pagers being both a data structure ("allocate a
pager") and a collection of routines. The idea of a pager structure has
escentially been eliminated. Objects now have types, and this type is
used to index the appropriate pager. In most cases, items in the pager
structure were duplicated in the object data structure and thus were
unnecessary. In the few cases that remained, a un_pager structure union
was created in the object to contain these items.
3) Because of the cleanup of #1 & #2, a lot of unnecessary layering can now
be removed. For instance, vm_object_enter(), vm_object_lookup(),
vm_object_remove(), and the associated object hash list were some of the
things that were removed.
4) simple_lock's removed. Discussion with several people reveals that the
SMP locking primitives used in the VM system aren't likely the mechanism
that we'll be adopting. Even if it were, the locking that was in the code
was very inadequate and would have to be mostly re-done anyway. The
locking in a uni-processor kernel was a no-op but went a long way toward
making the code difficult to read and debug.
5) Places that attempted to kludge-up the fact that we don't have kernel
thread support have been fixed to reflect the reality that we are really
dealing with processes, not threads. The VM system didn't have complete
thread support, so the comments and mis-named routines were just wrong.
We now use tsleep and wakeup directly in the lock routines, for instance.
6) Where appropriate, the pagers have been improved, especially in the
pager_alloc routines. Most of the pager_allocs have been rewritten and
are now faster and easier to maintain.
7) The pagedaemon pageout clustering algorithm has been rewritten and
now tries harder to output an even number of pages before and after
the requested page. This is sort of the reverse of the ideal pagein
algorithm and should provide better overall performance.
8) Unnecessary (incorrect) casts to caddr_t in calls to tsleep & wakeup
have been removed. Some other unnecessary casts have also been removed.
9) Some almost useless debugging code removed.
10) Terminology of shadow objects vs. backing objects straightened out.
The fact that the vm_object data structure escentially had this
backwards really confused things. The use of "shadow" and "backing
object" throughout the code is now internally consistent and correct
in the Mach terminology.
11) Several minor bug fixes, including one in the vm daemon that caused
0 RSS objects to not get purged as intended.
12) A "default pager" has now been created which cleans up the transition
of objects to the "swap" type. The previous checks throughout the code
for swp->pg_data != NULL were really ugly. This change also provides
the rudiments for future backing of "anonymous" memory by something
other than the swap pager (via the vnode pager, for example), and it
allows the decision about which of these pagers to use to be made
dynamically (although will need some additional decision code to do
this, of course).
13) (dyson) MAP_COPY has been deprecated and the corresponding "copy
object" code has been removed. MAP_COPY was undocumented and non-
standard. It was furthermore broken in several ways which caused its
behavior to degrade to MAP_PRIVATE. Binaries that use MAP_COPY will
continue to work correctly, but via the slightly different semantics
of MAP_PRIVATE.
14) (dyson) Sharing maps have been removed. It's marginal usefulness in a
threads design can be worked around in other ways. Both #12 and #13
were done to simplify the code and improve readability and maintain-
ability. (As were most all of these changes)
TODO:
1) Rewrite most of the vnode pager to use VOP_GETPAGES/PUTPAGES. Doing
this will reduce the vnode pager to a mere fraction of its current size.
2) Rewrite vm_fault and the swap/vnode pagers to use the clustering
information provided by the new haspage pager interface. This will
substantially reduce the overhead by eliminating a large number of
VOP_BMAP() calls. The VOP_BMAP() filesystem interface should be
improved to provide both a "behind" and "ahead" indication of
contiguousness.
3) Implement the extended features of pager_haspage in swap_pager_haspage().
It currently just says 0 pages ahead/behind.
4) Re-implement the swap device (swstrategy) in a more elegant way, perhaps
via a much more general mechanism that could also be used for disk
striping of regular filesystems.
5) Do something to improve the architecture of vm_object_collapse(). The
fact that it makes calls into the swap pager and knows too much about
how the swap pager operates really bothers me. It also doesn't allow
for collapsing of non-swap pager objects ("unnamed" objects backed by
other pagers).
218 lines
8.6 KiB
C
218 lines
8.6 KiB
C
/*
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* The Mach Operating System project at Carnegie-Mellon University.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* from: @(#)vm_map.h 8.3 (Berkeley) 3/15/94
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*
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*
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* Copyright (c) 1987, 1990 Carnegie-Mellon University.
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* All rights reserved.
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*
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* Authors: Avadis Tevanian, Jr., Michael Wayne Young
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*
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* Permission to use, copy, modify and distribute this software and
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* its documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
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* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
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* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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*
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* Carnegie Mellon requests users of this software to return to
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*
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* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
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* School of Computer Science
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* Carnegie Mellon University
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* Pittsburgh PA 15213-3890
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*
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* any improvements or extensions that they make and grant Carnegie the
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* rights to redistribute these changes.
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*
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* $Id: vm_map.h,v 1.5 1995/03/16 18:17:17 bde Exp $
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*/
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/*
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* Virtual memory map module definitions.
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*/
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#ifndef _VM_MAP_
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#define _VM_MAP_
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/*
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* Types defined:
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*
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* vm_map_t the high-level address map data structure.
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* vm_map_entry_t an entry in an address map.
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* vm_map_version_t a timestamp of a map, for use with vm_map_lookup
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*/
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/*
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* Objects which live in maps may be either VM objects, or
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* another map (called a "sharing map") which denotes read-write
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* sharing with other maps.
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*/
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union vm_map_object {
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struct vm_object *vm_object; /* object object */
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struct vm_map *share_map; /* share map */
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struct vm_map *sub_map; /* belongs to another map */
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};
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/*
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* Address map entries consist of start and end addresses,
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* a VM object (or sharing map) and offset into that object,
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* and user-exported inheritance and protection information.
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* Also included is control information for virtual copy operations.
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*/
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struct vm_map_entry {
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struct vm_map_entry *prev; /* previous entry */
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struct vm_map_entry *next; /* next entry */
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vm_offset_t start; /* start address */
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vm_offset_t end; /* end address */
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union vm_map_object object; /* object I point to */
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vm_offset_t offset; /* offset into object */
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boolean_t is_a_map:1, /* Is "object" a map? */
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is_sub_map:1, /* Is "object" a submap? */
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/* Only in sharing maps: */
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copy_on_write:1, /* is data copy-on-write */
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needs_copy:1; /* does object need to be copied */
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/* Only in task maps: */
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vm_prot_t protection; /* protection code */
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vm_prot_t max_protection; /* maximum protection */
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vm_inherit_t inheritance; /* inheritance */
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int wired_count; /* can be paged if = 0 */
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};
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/*
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* Maps are doubly-linked lists of map entries, kept sorted
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* by address. A single hint is provided to start
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* searches again from the last successful search,
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* insertion, or removal.
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*/
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struct vm_map {
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struct pmap *pmap; /* Physical map */
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lock_data_t lock; /* Lock for map data */
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struct vm_map_entry header; /* List of entries */
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int nentries; /* Number of entries */
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vm_size_t size; /* virtual size */
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boolean_t is_main_map; /* Am I a main map? */
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int ref_count; /* Reference count */
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vm_map_entry_t hint; /* hint for quick lookups */
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vm_map_entry_t first_free; /* First free space hint */
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boolean_t entries_pageable; /* map entries pageable?? */
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unsigned int timestamp; /* Version number */
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#define min_offset header.start
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#define max_offset header.end
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};
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/*
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* Map versions are used to validate a previous lookup attempt.
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*
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* Since lookup operations may involve both a main map and
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* a sharing map, it is necessary to have a timestamp from each.
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* [If the main map timestamp has changed, the share_map and
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* associated timestamp are no longer valid; the map version
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* does not include a reference for the imbedded share_map.]
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*/
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typedef struct {
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int main_timestamp;
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vm_map_t share_map;
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int share_timestamp;
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} vm_map_version_t;
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/*
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* Macros: vm_map_lock, etc.
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* Function:
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* Perform locking on the data portion of a map.
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*/
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#define vm_map_lock(map) { \
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lock_write(&(map)->lock); \
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(map)->timestamp++; \
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}
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#define vm_map_unlock(map) lock_write_done(&(map)->lock)
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#define vm_map_lock_read(map) lock_read(&(map)->lock)
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#define vm_map_unlock_read(map) lock_read_done(&(map)->lock)
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/*
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* Functions implemented as macros
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*/
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#define vm_map_min(map) ((map)->min_offset)
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#define vm_map_max(map) ((map)->max_offset)
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#define vm_map_pmap(map) ((map)->pmap)
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/* XXX: number of kernel maps and entries to statically allocate */
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#define MAX_KMAP 10
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#define MAX_KMAPENT 128
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#ifdef KERNEL
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extern vm_offset_t kentry_data;
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extern vm_size_t kentry_data_size;
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boolean_t vm_map_check_protection __P((vm_map_t, vm_offset_t, vm_offset_t, vm_prot_t));
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int vm_map_copy __P((vm_map_t, vm_map_t, vm_offset_t, vm_size_t, vm_offset_t, boolean_t, boolean_t));
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void vm_map_copy_entry __P((vm_map_t, vm_map_t, vm_map_entry_t, vm_map_entry_t));
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struct pmap;
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vm_map_t vm_map_create __P((struct pmap *, vm_offset_t, vm_offset_t, boolean_t));
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void vm_map_deallocate __P((vm_map_t));
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int vm_map_delete __P((vm_map_t, vm_offset_t, vm_offset_t));
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vm_map_entry_t vm_map_entry_create __P((vm_map_t));
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void vm_map_entry_delete __P((vm_map_t, vm_map_entry_t));
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void vm_map_entry_dispose __P((vm_map_t, vm_map_entry_t));
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void vm_map_entry_unwire __P((vm_map_t, vm_map_entry_t));
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int vm_map_find __P((vm_map_t, vm_object_t, vm_offset_t, vm_offset_t *, vm_size_t, boolean_t));
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int vm_map_findspace __P((vm_map_t, vm_offset_t, vm_size_t, vm_offset_t *));
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int vm_map_inherit __P((vm_map_t, vm_offset_t, vm_offset_t, vm_inherit_t));
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void vm_map_init __P((struct vm_map *, vm_offset_t, vm_offset_t, boolean_t));
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int vm_map_insert __P((vm_map_t, vm_object_t, vm_offset_t, vm_offset_t, vm_offset_t));
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int vm_map_lookup __P((vm_map_t *, vm_offset_t, vm_prot_t, vm_map_entry_t *, vm_object_t *,
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vm_offset_t *, vm_prot_t *, boolean_t *, boolean_t *));
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void vm_map_lookup_done __P((vm_map_t, vm_map_entry_t));
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boolean_t vm_map_lookup_entry __P((vm_map_t, vm_offset_t, vm_map_entry_t *));
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int vm_map_pageable __P((vm_map_t, vm_offset_t, vm_offset_t, boolean_t));
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int vm_map_clean __P((vm_map_t, vm_offset_t, vm_offset_t, boolean_t, boolean_t));
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void vm_map_print __P((vm_map_t, boolean_t));
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int vm_map_protect __P((vm_map_t, vm_offset_t, vm_offset_t, vm_prot_t, boolean_t));
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void vm_map_reference __P((vm_map_t));
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int vm_map_remove __P((vm_map_t, vm_offset_t, vm_offset_t));
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void vm_map_simplify __P((vm_map_t, vm_offset_t));
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void vm_map_simplify_entry __P((vm_map_t, vm_map_entry_t));
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void vm_map_startup __P((void));
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int vm_map_submap __P((vm_map_t, vm_offset_t, vm_offset_t, vm_map_t));
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#endif
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#endif /* _VM_MAP_ */
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