OSPP Chapters 8-10
the conversion from the memory address the program thinks it is referencing to the physical
location of the memory - ANS-address translation
an address that must be translated to produce an address in physical memory - ANS-virtual
address
an address in physical memory - ANS-physical address
used to determine which addresses in physical memory a program is allowed to use. The virtual
address is added to the base to generate the physical address; the bound register is checked
against the virtual address to prevent a process from reading or writing outside of its allocated
memory region. - ANS-base and bound registers, a.k.a. relocation registers
a virtual memory mechanism where addresses are translated by table lookup, where each entry
in the table is to a variable-size memory region - ANS-Segmentation
a portion of virtual memory controlled by an array; a contiguous region of virtual memory. Can
be located anywhere in physical memory. - ANS-Segment
in a system that allocates memory in contiguous regions, the unusable memory between valid
contiguous allocations. A new request for memory may find no single free region that is both
contiguous and large enough, even though there is enough free memory in aggregate -
ANS-external fragmentation
table that contains the base, bound, and the access level of each segment that has been
allocated - ANS-segment table
register of the segment table that contains the base for each segment - ANS-segment table
base register
register of the segment table that contains the bound of the segment in the segment table -
ANS-segment table limit register
contains the base address, bound address, and access permissions of a segment -
ANS-segment table entry
a data structure used by the memory management system to keep track of the state of physical
page frames, such as which processes reference the page frame - ANS-core map
, a method of sharing physical memory between two logically distinct copies (eg, in different
processes). Each shared page is marked as read-only so that the operating system kernel is
invoked and can make a copy of the page if either process tries to write it. The process can then
modify the copy and resume normal execution - ANS-Copy-on-write
a method for clearing memory only if the memory is used, rather than in advance. If the first
access to memory triggers a trap to the kernel, the kernel can zero the memory and then
resume - ANS-Zero-on-reference
a hardware address translation mechanism where memory is allocated in aligned, fixed-size
chunks, called pages. Any virtual page can be assigned to any physical page frame -
ANS-paged memory
a fixed-length contiguous block of virtual memory, described by a single entry in the page table.
It is the smallest unit of data for memory management in a virtual memory operating system. -
ANS-virtual page
- ANS-
an aligned, fixed-size chunk of physical memory that can hold a virtual page - ANS-page frame
with paged allocation of memory, the unusable memory at the end of a page because a process
can only be allocated memory in page-sized chunks - ANS-internal fragmentation
if multiple pages are allocated in a row, these types of unmapped pages are placed around
them. If they are accessed an exception is thrown. - ANS-guard page
contains a list of pointers to page frames. Since frames are fixed size and a power of two the
page table entries only need to provide the upper bits of the page frame address - ANS-page
table
contains a pointer to a page frame along with the access permissions. Since frames are fixed
size and a power of two the page table entries only need to provide the upper bits of the page
frame address - ANS-page table entry
a hardware mechanism where physical memory is allocated in page frames, but virtual
addresses are segmented - ANS-paged segmentation
a virtual memory mechanism where physical memory is allocated in page frames, and virtual
addresses are translated to physical addresses through multiple levels of page tables -
ANS-multi-level paging
- ANS-
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