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国外开发的著名分布式操作系统mach的有关代码文章

8990 67295 MT
(\267)SH
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9700 XM
(Calls made by the kernel on the data manager.  Table 3-5 summarizes this interface.)SH
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8990 69053 MT
(\267)SH
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9700 XM
(Calls made by the data manager on the)
112 W( Mach kernel to control use of its memory object.  Table 3-6)113 W
9700 70158 MT
(summarizes these operations.)SH
7200 71535 MT
(As in other Mach interfaces, these calls are implemented)
109 W( using IPC; the first argument to each call is the port to)108 W
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30350 4286 MT
(6)SH
7200 7886 MT
(which the request is sent, and represents the object to be affected by the operation.)SH
46800 50 7200 9463 UL
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7200 12163 MT
(vm_allocate_with_pager\050task, address, size, anywhere, memory_object, offset\051)SH
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10800 12968 MT
(Allocate a region of memory at the specified address.  The specified memory object provides the initial)
13 W( data values and)14 W
10800 13769 MT
(receives changes.)SH
45800 50 8200 15346 UL
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21907 18061 MT
(Table 3-4:)SH
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26768 XM
(Application to Kernel Interface)SH
45800 50 8200 19638 UL
8200 21917 MT
(A memory object may be mapped into the address space of an)
457 W( application task by exercising the)456 W
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7200 23294 MT
(vm_allocate_with_pager)SH
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17397 XM
(primitive, specifying that memory object)
3 W( \050a port\051.  A single memory object may be mapped)4 W
7200 24671 MT
(in more than once, possibly in different tasks.)SH
8200 27150 MT
(The memory region)
149 W( specified by)148 W
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22245 XM
(address)SH
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25754 XM
(in the)148 W
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28550 XM
(vm_allocate_with_pager)SH
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38892 XM
(call will be mapped to the specified)148 W
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7200 28527 MT
(offset)SH
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9658 XM
(in the memory object.  The offset into)
41 W( the memory object is not required to align on system page boundaries;)42 W
7200 29904 MT
(however, the Mach kernel will only guarantee consistency among mappings with similar page alignment.)SH
46800 50 7200 31481 UL
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7200 34181 MT
(pager_init\050memory_object, pager_request_port, pager_name\051)SH
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10800 34986 MT
(Initialize a memory object.)SH
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7200 36099 MT
(pager_data_request\050memory_object, pager_request_port, offset, length, desired_access\051)SH
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10800 36904 MT
(Requests data from an external data manager.)SH
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7200 38017 MT
(pager_data_write\050memory_object, offset, data, data_count\051)SH
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10800 38822 MT
(Writes data back to a memory object.)SH
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7200 39935 MT
(pager_data_unlock\050memory_object, pager_request_port, offset, length, desired_access\051)SH
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10800 40740 MT
(Requests that data be unlocked.)SH
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7200 41853 MT
(pager_create\050old_memory_object, new_memory_object, new_request_port, new_name\051)SH
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10800 42658 MT
(Accept responsibility for a kernel-created memory object.)SH
46800 50 7200 45337 UL
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21422 48052 MT
(Table 3-5:)SH
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26283 XM
(Kernel to Data Manager Interface)SH
45800 50 8200 49629 UL
8200 51908 MT
(When asked to map a memory object for the first time, the kernel responds by)
92 W( making a)91 W
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45144 XM
(pager_init)SH
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49652 XM
(call on the)91 W
7200 53285 MT
(memory object.  Included in this message are:)SH
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8990 54738 MT
(\267)SH
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9700 XM
(a)SH
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10475 XM
(pager request)82 W
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16416 XM
(port that the data manager may use to make cache management requests of the Mach)82 W
9700 55843 MT
(kernel;)SH
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8990 57601 MT
(\267)SH
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9700 XM
(a)SH
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10655 XM
(pager name)261 W
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16176 XM
(port that the kernel will use to identify this memory)
261 W( object to other tasks in the)260 W
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25975 58369 MT
(3)SH
10 SS 
9700 58714 MT
(description returned by)SH
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19226 XM
(vm_regions)SH
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24142 XM
(calls)SH
26375 XM
(.)SH
7200 60091 MT
(The Mach kernel holds send rights to the memory object port, and both send and receive rights on the)
28 W( pager request)27 W
7200 61468 MT
(and pager name ports.)SH
8200 63947 MT
(If a memory object is mapped into the address space)
61 W( of more than one task on different hosts \050with independent)62 W
7200 65324 MT
(Mach kernels\051, the data manager)
19 W( will receive an initialization call from each kernel.  For identification purposes, the)18 W
7200 66701 MT
(pager request port is specified in future operations made by the kernel.)SH
10800 50 7200 69428 UL
6 SS 
8000 70767 MT
(3)SH
8 SS 
8300 71076 MT
(The memory object and request ports)
140 W( cannot be used for this purpose, as access to those ports allows complete access to the data and)141 W
7200 72000 MT
(management functions.)SH
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30350 4286 MT
(7)SH
46800 50 7200 7400 UL
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7200 10100 MT
(pager_data_provided\050pager_request_port, offset, data, data_count, lock_value\051)SH
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10800 10905 MT
(Supplies the kernel with the data contents of a region of a memory object.)SH
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7200 12018 MT
(pager_data_lock\050pager_request_port, offset, length, lock_value\051)SH
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10800 12823 MT
(Restricts cache access to the specified data.)SH
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7200 13936 MT
(pager_flush_request\050pager_request_port, offset, length\051)SH
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10800 14741 MT
(Forces cached data to be invalidated.)SH
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7200 15854 MT
(pager_clean_request\050pager_request_port, offset, length\051)SH
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10800 16659 MT
(Forces cached data to be written back to the memory object.)SH
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7200 17772 MT
(pager_cache\050pager_request_port, may_cache_object\051)SH
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10800 18577 MT
(Tells the kernel whether it may retain cached data from the)
92 W( memory object even after all references to it have been)93 W
10800 19378 MT
(removed.)SH
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7200 20491 MT
(pager_data_unavailable\050pager_request_port, offset, size\051)SH
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10800 21296 MT
(Notifies kernel that no data exists for that region of a memory object.)SH
46800 50 7200 23975 UL
10 /Times-Bold AF
21422 26690 MT
(Table 3-6:)SH
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26283 XM
(Data Manager to Kernel Interface)SH
45800 50 8200 28267 UL
8200 30546 MT
(In order to process)
15 W( a cache miss \050)14 W
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(i.e.)SH
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(, page fault\051, the kernel issues a)14 W
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35836 XM
(pager_data_request)SH
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44155 XM
(call specifying the range)14 W
7200 31923 MT
(\050usually a single page\051 desired and the pager request port to which the data should be returned.)SH
8200 34402 MT
(To clean dirty pages, the kernel performs a)71 W
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26180 XM
(pager_data_write)SH
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33668 XM
(call specifying the location)
71 W( in the memory object,)72 W
7200 35779 MT
(and including the data to be written.  When the data manager no longer needs the data \050)24 W
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(e.g.)SH
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(, it has been successfully)24 W
7200 37156 MT
(written to secondary storage\051, it is expected to use the)SH
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28946 XM
(vm_deallocate)SH
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35028 XM
(call to release the cache resources.)SH
8200 39635 MT
(These remote procedure)
104 W( calls made by the Mach kernel are asynchronous; the calls do not have explicit return)105 W
7200 41012 MT
(arguments and the kernel does not wait for acknowledgement.)SH
8200 43491 MT
(A data)
61 W( manager passes data for a memory object to the kernel by using the)60 W
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39178 XM
(pager_data_provided)SH
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48154 XM
(call. This)
370 W( call)60 W
7200 44868 MT
(specifies the location of the data within the memory object, and includes the memory object)
29 W( data. It is usually made)30 W
7200 46245 MT
(in response to a)SH
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13699 XM
(pager_data_request)SH
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22004 XM
(call made to the data manager by the kernel.)SH
8200 48724 MT
(Typical data managers will only provide data upon)
313 W( demand \050when processing)312 W
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42939 XM
(pager_data_request)SH
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51556 XM
(calls\051;)SH
7200 50101 MT
(however, advanced data mangers)
29 W( may provide more data than requested.  The Mach kernel can only handle integral)30 W
7200 51478 MT
(multiples of the system page size in any one call and partial pages are discarded.)SH
8200 53957 MT
(Since the data manager may have external constraints)
9 W( on the consistency of its memory object, the Mach interface)8 W
7200 55334 MT
(provides some)
303 W( functions to control caching; these calls are made using the pager request port provided at)304 W
7200 56711 MT
(initialization time.)SH
8200 59190 MT
(A)SH
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9262 XM
(pager_flush_request)SH
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17824 XM
(call causes the kernel to invalidate its cached copy of the data in question, writing)
90 W( back)89 W
7200 60567 MT
(modifications if necessary.  A)57 W
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19705 XM
(pager_clean_request)SH
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28455 XM
(call asks the kernel to)
57 W( write back modifications, but allows the)58 W
7200 61944 MT
(kernel to continue to use the cached data.  The kernel uses the)96 W
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33442 XM
(pager_data_write)SH
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40955 XM
(call in response, just as)
96 W( when it)95 W
7200 63321 MT
(initiates a cache replacement.)SH
8200 65800 MT
(A data manager may restrict the use of cached data by issuing a)34 W
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34330 XM
(pager_data_lock)SH
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41391 XM
(request, specifying)
34 W( the types of)35 W
7200 67177 MT
(access \050any combination of read, write, and)
1 W( execute\051 that must be prevented.  For example, a data manager may wish)SH
7200 68554 MT
(to temporarily allow read-only)
153 W( access to cached data.  The locking on a page may later be changed as deemed)154 W
7200 69931 MT
(necessary by the data manager.  [To avoid)
4 W( race conditions, the)3 W
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32428 XM
(pager_data_provided)SH
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41347 XM
(call also includes an initial lock)3 W
7200 71308 MT
(value.])SH
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30350 4286 MT
(8)SH
8200 7886 MT
(When a user task requires greater access to cached data than the data manager has permitted \050)17 W
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(e.g.)SH
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(, a write)
17 W( fault on)18 W
7200 9263 MT
(a page made read-only by a)21 W
/Times-Italic SF
18600 XM
(pager_data_lock)SH
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25647 XM
(call\051, the kernel issues a)20 W
/Times-Italic SF
35578 XM
(pager_data_unlock)SH
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43625 XM
(call. The)
290 W( data manager is)20 W
7200 10640 MT
(expected to respond by changing the locking on that data when it is able to do so.)SH
8200 13119 MT
(When no references to a memory object remain,)
132 W( and all modifications have been written back to the memory)133 W
7200 14496 MT
(object, the kernel deallocates its rights to the three ports associated with that memory object.  The data)
119 W( manager)118 W
7200 15873 MT
(receives notification of the destruction of)
158 W( the request and name ports, at which time it can perform appropriate)159 W
7200 17250 MT
(shutdown.)SH
8200 19729 MT
(In order to)
18 W( attain better cache performance, a data manager may permit the data for a memory object to be cached)17 W
7200 21106 MT
(even after all)
21 W( application address map references are gone by calling)22 W
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35070 XM
(pager_cache)SH
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(. Permitting)
294 W( such caching is in no)22 W
7200 22483 MT
(way binding; the kernel may)
30 W( choose to relinquish its access to the memory object ports as it deems necessary for its)29 W
7200 23860 MT
(cache management.  A data manager may later rescind its permission to cache the memory object.)SH
8200 26339 MT
(The Mach)
155 W( kernel itself creates memory objects to provide backing storage for zero-filled memory created by)156 W
8 SS 
12088 27371 MT
(4)SH
10 /Times-Italic AF
7200 27716 MT
(vm_allocate)SH
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12488 XM
(. The)
300 W( kernel allocates a port to represent this memory)
25 W( object, and passes it to a)24 W
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44706 XM
(default pager)24 W
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50365 XM
(task, that)24 W
8 SS 
29223 28748 MT