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88 Cards in this Set
- Front
- Back
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Virtualization
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??? |
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virtual machine
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??? |
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physical memory
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How much real storage(RAM) you have in your computer.
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address space
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An address space is a range of valid addresses in memory that are available for a program or process.
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Concurrency
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Allows a program to work properly if stored or loaded out of order.
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Multi-threaded
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A technique that allows multiple instances of the same copy of a program.
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Volatile
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Memory that is only retained when powered.
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solid-state drives (SSDs)
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A storage device with no moving parts, that stores memory in microchips.
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kernel mode
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The memory resident portion of the OS which controls all functions.
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Multiprogramming
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Running two or more programs or instructions simultaneously by a computer with more than one central processor.
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time sharing
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The process of sharing the CPU amongst other users or programs.
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context switch
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The process of switching the use of the CPU from one process to another.
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Process
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An instance of a program being executed.
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instruction pointer
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The indication of where a program is in its execution sequence.
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Paging
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The process of storing and retrieving data from storage to main memory.
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Swapping
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Replacing one segment of a program with another and then back again if necessary.
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Run-time
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The length a program takes to run start to finish.
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Stack
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memory that grows upward. Variable and return addresses get placed on the stack.
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Heap
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memory that grows downward.
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Running
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An executed program which is currently active.
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Ready
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Something that is built in.
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Blocked
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A blocked program is a program waiting for something to happen before it can continue.
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limited direct execution
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Running a program on the cpu with limited control.(The OS might take over if overstepping bounds)
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Trap
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An interrupt caused by a certain condition
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Cooperative
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Equal allocation of the CPU ex. Round Robin
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interrupt handle
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Allows access to the CPU only when requested.
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First In, First Out (FIFO)
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A technique in CPU scheduling that allows access to the CPU based on order of arrival.
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Shortest Job First (SJF)
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A technique in CPU scheduling that allows the shortest job access to the CPU first.
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Preemptive
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One method of relinqishing the cpu for multi-tasking
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Shortest Time-to-Completion First (STCF)
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A technique in CPU scheduling that allows whichever process has the least amount of time remaining access to the CPU first.
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Multi-level Feedback Queue (MLFQ)
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use of several different CPU scheduling techniques
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priority level
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Determines which process goes first. Highest priority first.
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Starvation
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The prevention of a process from ever getting access to the CPU
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boost the priority
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helps prevent deadlock by boosting priority after a while.
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Multiprocessor
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The use of two or more processing units
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Caches
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a hardware or software component that stores data so future requests for that data can be served faster
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temporal locality
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Something has Temporal Locality if it has been used recntly with another process.
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spatial locality
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Something has Spatial Locality if it is stored(physically) near something that has been recently used.
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Interposing
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Interacts with the OS only when needed.
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virtual address
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Where in virtual memory something is located
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Relocate
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To relocate data from one place to another.
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dynamic relocation
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The process of relocating data currently in the computer memory to other parts of the computer creating a more efficient memory storage while a program is still active.
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base and bounds
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A simple form of virtual memory where access to computer memory is controlled by one or a small number of sets of processor registers called base and bounds registers
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address translation
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When the OS changes the address of program.
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memory management unit (MMU)
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A computer hardware component that handles all memory and caching operations associated with the processor.
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internal fragmentation
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The wasted space within each allocated block because of rounding up from the actual requested allocation to the allocation granularity.
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Segmentation
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The wasted space within each allocated block because of rounding up from the actual requested allocation to the allocation granularity.
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process control block (PCB)
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A data structure in the operating system kernel containing the information needed to manage a particular process.
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Best-fit
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A method of selecting a contiguous area of memory that is to be allocated for a segment. The smallest chunk of data that fits in the area gets placed first.
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Worst-fit
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A method of selecting a contiguous area of memory that is to be allocated for a segment. It selects the largest available hole in memory that can fit a needed segment, so as to leave a large hole for other segments.
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First-Fit
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The free-space list scanned in order of starting address, and the allocation made from the first free area whose size exceeds that of the request.
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Page
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segments of code of all the same size.
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page frames
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A physical entity with its own page frame number (PFN).
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physical frame number (PFN)
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the physical location of a frame. ???
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page table
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The data structure used by a virtual memory system in a computer operating system to store the mapping between virtual addresses and physical addresses.
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translation-lookaside buffer
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A memory cache that stores recent translations of virtual memory to physical addresses for faster retrieval.
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TLB miss
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The first step in executing a prefetch is translating the virtual data address to a physical address.
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TLB hit
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???
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least-recently-used (LRU)
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A rule used in a paging system which selects a page to be paged out if it has been used (read or written) less recently than any other page.
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swap space
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A portion of a hard disk drive that is used for virtual memory. Memory is used to hold portions of the operating system, programs and data that are currently in use or that are frequently used.
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Page Fault
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An error that occurs when the operating system cannot find the data in virtual memory.
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page-replacement policy
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An algorithms that decides which memory pages to page out when a page of memory needs to be allocated.
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Hybrid
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Hybrid computers are computers that exhibit features of analog computers and digital computers. ???
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Two-phased
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???
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Direct Memory Access (DMA)
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A method that allows an input/output (I/O) device to send or receive data directly to or from the main memory, bypassing the CPU to speed up memory operations.
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device driver
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Software that allows external hardware to function
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Platter
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The circular disk on which magnetic data is stored in a hard disk drive.
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Spindle
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A rotating shaft in a disk drive.
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rotations per minute (RPM)
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The rotation speed of the spindle.
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Track
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The Physical division of data in a disk drive.
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Disk Head or RW Head
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A device found on the arm of a hard drive that is used to read and write data from the hard drive's disk platter.
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disk arm
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A moveable arm attached to the RW Head allowing it to switch tracks.
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rotational delay
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The delay in rotating the disk to get to the data.
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seek time
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The delay in moving the disk arm to get to the data.
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Transfer
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To send data over a channel or bus line.
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shortest-seek-time-first (SSTF)
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scheduling algorithm to determine the motion of the disk's arm and head in servicing read and write requests. Shortest distance first.
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nearest-block-first (NBF)
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???
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elevator algorithm
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A disk scheduling algorithm to determine the motion of the disk's arm and head in servicing read and write requests.
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RAID
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Redundant Array of Independent Disks
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RAID 0
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RAID where you stripe data across separate disks to protect data.
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RAID 1
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RAID using mirroring and duplexing to protect data.
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RAID 5
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RAID by use of striping with distributed parity to protect data.
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RAID 10
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RAID by use of disk mirroring and disk striping to protect data.
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Striping
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Putting chunks of data from the same program or database on different disks.
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Parity
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a way to backup data on a separate disk
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Mirrored
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A copy of the data. Read twice, Write twice.
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Hot swap
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Allowing a component to be replaced or added while the computer is still running.
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Deadlock
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When two or more programs cannot continue due to each needing what the other has locked.
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