![[BACK]](/cvsweb/icons/back.gif){kind=icon}
Return to vm_external.c CVS log ![[TXT]](/cvsweb/icons/text.gif){kind=icon}
![[DIR]](/cvsweb/icons/dir.gif){kind=icon}
Up to [GnuMach] / Gnu-Mach / vm|
Return to vm_external.c CVS log | Up to [GnuMach] / Gnu-Mach / vm |
1.1 root 1: /*
2: * Mach Operating System
3: * Copyright (c) 1991,1990,1989 Carnegie Mellon University
4: * All Rights Reserved.
5: *
6: * Permission to use, copy, modify and distribute this software and its
7: * documentation is hereby granted, provided that both the copyright
8: * notice and this permission notice appear in all copies of the
9: * software, derivative works or modified versions, and any portions
10: * thereof, and that both notices appear in supporting documentation.
11: *
12: * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
13: * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
14: * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
15: *
16: * Carnegie Mellon requests users of this software to return to
17: *
18: * Software Distribution Coordinator or [email protected]
19: * School of Computer Science
20: * Carnegie Mellon University
21: * Pittsburgh PA 15213-3890
22: *
23: * any improvements or extensions that they make and grant Carnegie Mellon
24: * the rights to redistribute these changes.
25: */
26: /*
27: * This module maintains information about the presence of
28: * pages not in memory. Since an external memory object
29: * must maintain a complete knowledge of its contents, this
30: * information takes the form of hints.
31: */
32:
33: #include <mach/boolean.h>
1.1.1.2 root 34: #include <kern/slab.h>
1.1 root 35: #include <vm/vm_external.h>
36: #include <mach/vm_param.h>
37: #include <kern/assert.h>
38:
39:
40:
41: boolean_t vm_external_unsafe = FALSE;
42:
1.1.1.2 root 43: struct kmem_cache vm_external_cache;
1.1 root 44:
45: /*
46: * The implementation uses bit arrays to record whether
47: * a page has been written to external storage. For
48: * convenience, these bit arrays come in two sizes
49: * (measured in bytes).
50: */
51:
52: #define SMALL_SIZE (VM_EXTERNAL_SMALL_SIZE/8)
53: #define LARGE_SIZE (VM_EXTERNAL_LARGE_SIZE/8)
54:
1.1.1.2 root 55: struct kmem_cache vm_object_small_existence_map_cache;
56: struct kmem_cache vm_object_large_existence_map_cache;
1.1 root 57:
58:
1.1.1.3 ! root 59: vm_external_t vm_external_create(vm_offset_t size)
1.1 root 60: {
61: vm_external_t result;
62: vm_size_t bytes;
63:
1.1.1.2 root 64: result = (vm_external_t) kmem_cache_alloc(&vm_external_cache);
1.1 root 65: result->existence_map = (char *) 0;
66:
67: bytes = (atop(size) + 07) >> 3;
68: if (bytes <= SMALL_SIZE) {
69: result->existence_map =
1.1.1.2 root 70: (char *) kmem_cache_alloc(&vm_object_small_existence_map_cache);
1.1 root 71: result->existence_size = SMALL_SIZE;
72: } else if (bytes <= LARGE_SIZE) {
73: result->existence_map =
1.1.1.2 root 74: (char *) kmem_cache_alloc(&vm_object_large_existence_map_cache);
1.1 root 75: result->existence_size = LARGE_SIZE;
76: }
77: return(result);
78: }
79:
1.1.1.3 ! root 80: void vm_external_destroy(vm_external_t e)
1.1 root 81: {
82: if (e == VM_EXTERNAL_NULL)
83: return;
84:
85: if (e->existence_map != (char *) 0) {
86: if (e->existence_size <= SMALL_SIZE) {
1.1.1.2 root 87: kmem_cache_free(&vm_object_small_existence_map_cache,
1.1 root 88: (vm_offset_t) e->existence_map);
89: } else {
1.1.1.2 root 90: kmem_cache_free(&vm_object_large_existence_map_cache,
1.1 root 91: (vm_offset_t) e->existence_map);
92: }
93: }
1.1.1.2 root 94: kmem_cache_free(&vm_external_cache, (vm_offset_t) e);
1.1 root 95: }
96:
97: vm_external_state_t _vm_external_state_get(e, offset)
1.1.1.3 ! root 98: const vm_external_t e;
! 99: vm_offset_t offset;
1.1 root 100: {
101: unsigned
102: int bit, byte;
103:
104: if (vm_external_unsafe ||
105: (e == VM_EXTERNAL_NULL) ||
106: (e->existence_map == (char *) 0))
107: return(VM_EXTERNAL_STATE_UNKNOWN);
108:
109: bit = atop(offset);
110: byte = bit >> 3;
111: if (byte >= e->existence_size) return (VM_EXTERNAL_STATE_UNKNOWN);
112: return( (e->existence_map[byte] & (1 << (bit & 07))) ?
113: VM_EXTERNAL_STATE_EXISTS : VM_EXTERNAL_STATE_ABSENT );
114: }
115:
1.1.1.3 ! root 116: void vm_external_state_set(
! 117: vm_external_t e,
! 118: vm_offset_t offset,
! 119: vm_external_state_t state)
1.1 root 120: {
121: unsigned
122: int bit, byte;
123:
124: if ((e == VM_EXTERNAL_NULL) || (e->existence_map == (char *) 0))
125: return;
126:
127: if (state != VM_EXTERNAL_STATE_EXISTS)
128: return;
129:
130: bit = atop(offset);
131: byte = bit >> 3;
132: if (byte >= e->existence_size) return;
133: e->existence_map[byte] |= (1 << (bit & 07));
134: }
135:
1.1.1.2 root 136: void vm_external_module_initialize(void)
1.1 root 137: {
138: vm_size_t size = (vm_size_t) sizeof(struct vm_external);
139:
1.1.1.2 root 140: kmem_cache_init(&vm_external_cache, "vm_external", size, 0,
141: NULL, NULL, NULL, 0);
1.1 root 142:
1.1.1.2 root 143: kmem_cache_init(&vm_object_small_existence_map_cache,
144: "small_existence_map", SMALL_SIZE, 0,
145: NULL, NULL, NULL, 0);
146:
147: kmem_cache_init(&vm_object_large_existence_map_cache,
148: "large_existence_map", LARGE_SIZE, 0,
149: NULL, NULL, NULL, 0);
1.1 root 150: }
This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.