Sat Jan 28 14:37:35 2012 UTC ()
Describe UVM object and explain lock sharing a little.


(rmind)
diff -r1.31 -r1.32 src/sys/uvm/uvm_object.h

cvs diff -r1.31 -r1.32 src/sys/uvm/uvm_object.h (switch to unified diff)

--- src/sys/uvm/uvm_object.h 2011/06/12 03:36:03 1.31
+++ src/sys/uvm/uvm_object.h 2012/01/28 14:37:35 1.32
@@ -1,108 +1,116 @@ @@ -1,108 +1,116 @@
1/* $NetBSD: uvm_object.h,v 1.31 2011/06/12 03:36:03 rmind Exp $ */ 1/* $NetBSD: uvm_object.h,v 1.32 2012/01/28 14:37:35 rmind Exp $ */
2 2
3/* 3/*
4 * Copyright (c) 1997 Charles D. Cranor and Washington University. 4 * Copyright (c) 1997 Charles D. Cranor and Washington University.
5 * All rights reserved. 5 * All rights reserved.
6 * 6 *
7 * Redistribution and use in source and binary forms, with or without 7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions 8 * modification, are permitted provided that the following conditions
9 * are met: 9 * are met:
10 * 1. Redistributions of source code must retain the above copyright 10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer. 11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright 12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the 13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution. 14 * documentation and/or other materials provided with the distribution.
15 * 15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 * 26 *
27 * from: Id: uvm_object.h,v 1.1.2.2 1998/01/04 22:44:51 chuck Exp 27 * from: Id: uvm_object.h,v 1.1.2.2 1998/01/04 22:44:51 chuck Exp
28 */ 28 */
29 29
30#ifndef _UVM_UVM_OBJECT_H_ 30#ifndef _UVM_UVM_OBJECT_H_
31#define _UVM_UVM_OBJECT_H_ 31#define _UVM_UVM_OBJECT_H_
32 32
33/* 
34 * uvm_object.h 
35 */ 
36 
37#include <sys/queue.h> 33#include <sys/queue.h>
38#include <sys/rbtree.h> 34#include <sys/rbtree.h>
39#include <uvm/uvm_pglist.h> 35#include <uvm/uvm_pglist.h>
40 36
41/* 37/*
42 * uvm_object: all that is left of mach objects. 38 * The UVM memory object interface. Notes:
 39 *
 40 * A UVM memory object represents a list of pages, which are managed by
 41 * the object's pager operations (uvm_object::pgops). All pages belonging
 42 * to an object are owned by it and thus protected by the object lock.
 43 *
 44 * The lock (uvm_object::vmobjlock) may be shared amongst the UVM objects.
 45 * By default, the lock is allocated dynamically using mutex_obj(9) cache.
 46 * Lock sharing is normally used when there is an underlying object. For
 47 * example, vnode representing a file may have an underlying node, which
 48 * is the case for tmpfs and layered file systems. In such case, vnode's
 49 * UVM object and the underlying UVM object shares the lock (note that the
 50 * vnode_t::v_interlock points to uvm_object::vmobjlock).
43 */ 51 */
44 52
45struct uvm_object { 53struct uvm_object {
46 kmutex_t * vmobjlock; /* lock on memq */ 54 kmutex_t * vmobjlock; /* lock on memq */
47 const struct uvm_pagerops *pgops; /* pager ops */ 55 const struct uvm_pagerops *pgops; /* pager ops */
48 struct pglist memq; /* pages in this object */ 56 struct pglist memq; /* pages in this object */
49 int uo_npages; /* # of pages in memq */ 57 int uo_npages; /* # of pages in memq */
50 unsigned uo_refs; /* reference count */ 58 unsigned uo_refs; /* reference count */
51 struct rb_tree rb_tree; /* tree of pages */ 59 struct rb_tree rb_tree; /* tree of pages */
52 LIST_HEAD(,ubc_map) uo_ubc; /* ubc mappings */ 60 LIST_HEAD(,ubc_map) uo_ubc; /* ubc mappings */
53}; 61};
54 62
55/* 63/*
56 * UVM_OBJ_KERN is a 'special' uo_refs value which indicates that the 64 * UVM_OBJ_KERN is a 'special' uo_refs value which indicates that the
57 * object is a kernel memory object rather than a normal one (kernel 65 * object is a kernel memory object rather than a normal one (kernel
58 * memory objects don't have reference counts -- they never die). 66 * memory objects don't have reference counts -- they never die).
59 * 67 *
60 * this value is used to detected kernel object mappings at uvm_unmap() 68 * this value is used to detected kernel object mappings at uvm_unmap()
61 * time. normally when an object is unmapped its pages eventaully become 69 * time. normally when an object is unmapped its pages eventaully become
62 * deactivated and then paged out and/or freed. this is not useful 70 * deactivated and then paged out and/or freed. this is not useful
63 * for kernel objects... when a kernel object is unmapped we always want 71 * for kernel objects... when a kernel object is unmapped we always want
64 * to free the resources associated with the mapping. UVM_OBJ_KERN 72 * to free the resources associated with the mapping. UVM_OBJ_KERN
65 * allows us to decide which type of unmapping we want to do. 73 * allows us to decide which type of unmapping we want to do.
66 */ 74 */
67#define UVM_OBJ_KERN (-2) 75#define UVM_OBJ_KERN (-2)
68 76
69#define UVM_OBJ_IS_KERN_OBJECT(uobj) \ 77#define UVM_OBJ_IS_KERN_OBJECT(uobj) \
70 ((uobj)->uo_refs == UVM_OBJ_KERN) 78 ((uobj)->uo_refs == UVM_OBJ_KERN)
71 79
72#ifdef _KERNEL 80#ifdef _KERNEL
73 81
74extern const struct uvm_pagerops uvm_vnodeops; 82extern const struct uvm_pagerops uvm_vnodeops;
75extern const struct uvm_pagerops uvm_deviceops; 83extern const struct uvm_pagerops uvm_deviceops;
76extern const struct uvm_pagerops ubc_pager; 84extern const struct uvm_pagerops ubc_pager;
77extern const struct uvm_pagerops aobj_pager; 85extern const struct uvm_pagerops aobj_pager;
78 86
79#define UVM_OBJ_IS_VNODE(uobj) \ 87#define UVM_OBJ_IS_VNODE(uobj) \
80 ((uobj)->pgops == &uvm_vnodeops) 88 ((uobj)->pgops == &uvm_vnodeops)
81 89
82#define UVM_OBJ_IS_DEVICE(uobj) \ 90#define UVM_OBJ_IS_DEVICE(uobj) \
83 ((uobj)->pgops == &uvm_deviceops) 91 ((uobj)->pgops == &uvm_deviceops)
84 92
85#define UVM_OBJ_IS_VTEXT(uobj) \ 93#define UVM_OBJ_IS_VTEXT(uobj) \
86 (UVM_OBJ_IS_VNODE(uobj) && uvn_text_p(uobj)) 94 (UVM_OBJ_IS_VNODE(uobj) && uvn_text_p(uobj))
87 95
88#define UVM_OBJ_IS_CLEAN(uobj) \ 96#define UVM_OBJ_IS_CLEAN(uobj) \
89 (UVM_OBJ_IS_VNODE(uobj) && uvn_clean_p(uobj)) 97 (UVM_OBJ_IS_VNODE(uobj) && uvn_clean_p(uobj))
90 98
91/* 99/*
92 * UVM_OBJ_NEEDS_WRITEFAULT: true if the uobj needs to detect modification. 100 * UVM_OBJ_NEEDS_WRITEFAULT: true if the uobj needs to detect modification.
93 * (ie. wants to avoid writable user mappings.) 101 * (ie. wants to avoid writable user mappings.)
94 * 102 *
95 * XXX bad name 103 * XXX bad name
96 */ 104 */
97 105
98#define UVM_OBJ_NEEDS_WRITEFAULT(uobj) \ 106#define UVM_OBJ_NEEDS_WRITEFAULT(uobj) \
99 (UVM_OBJ_IS_VNODE(uobj) && uvn_needs_writefault_p(uobj)) 107 (UVM_OBJ_IS_VNODE(uobj) && uvn_needs_writefault_p(uobj))
100 108
101#define UVM_OBJ_IS_AOBJ(uobj) \ 109#define UVM_OBJ_IS_AOBJ(uobj) \
102 ((uobj)->pgops == &aobj_pager) 110 ((uobj)->pgops == &aobj_pager)
103 111
104extern const rb_tree_ops_t uvm_page_tree_ops; 112extern const rb_tree_ops_t uvm_page_tree_ops;
105 113
106#endif /* _KERNEL */ 114#endif /* _KERNEL */
107 115
108#endif /* _UVM_UVM_OBJECT_H_ */ 116#endif /* _UVM_UVM_OBJECT_H_ */