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33 .Nd synchronize a mapped region
39 .Fn msync "void *addr" "size_t len" "int flags"
44 writes any modified pages back to the file system and updates
45 the file modification time.
48 is 0, all modified pages within the region containing
53 is non-zero, only those pages containing
57 succeeding locations will be examined.
60 argument may be specified as follows:
62 .Bl -tag -width ".Dv MS_INVALIDATE" -compact
66 Perform synchronous writes
68 Invalidate all cached data
79 Some or all of the pages in the specified region are locked and
86 is not a multiple of the hardware page size.
88 The addresses in the range starting at
92 bytes are outside the range allowed for the address space of a
93 process or specify one or more pages that are not mapped.
98 was both MS_ASYNC and MS_INVALIDATE.
99 Only one of these flags is allowed.
101 An error occurred while writing at least one of the pages in
102 the specified region.
113 system call first appeared in
118 system call is usually not needed since
120 implements a coherent file system buffer cache.
121 However, it may be used to associate dirty VM pages with file system
122 buffers and thus cause them to be flushed to physical media sooner