FINALS Flashcards
Programs on disk, ready to be brought into memory to execute
input queue
If memory location known a priori, absolute code can be generated; must recompile code if starting
location changes
Compile time
Must generate relocatable code if memory location is not known at compile time
Load time
Binding delayed until run time if the process can be moved during its execution from one memory segment to another
Execution time
generated by the CPU; also referred to
as virtual address
Logical address
address seen by the memory unit
Physical address
is the set of all logical addresses
generated by a program
Logical address space
is the set of all physical addresses
generated by a program
Physical address space
Hardware device that at run time maps virtual to physical
address
Memory-Management Unit (MMU)
system libraries and program code combined by
the loader into the binary program image
Static linking
linking postponed until execution time
Dynamic linking
Small piece of code, used to locate the appropriate
memory-resident library routine
stub
fast disk large enough to accommodate copies
of all memory images for all users; must provide direct access to
these memory images
Backing store
ready-to-run processes
which have memory images on disk
ready queue
can’t swap out as I/O would occur to wrong
process
Pending I/O
swapping variant used for priority-based
scheduling algorithms; lower-priority process is swapped out so
higher-priority process can be loaded and executed
Roll out, roll in
always transfer I/O to kernel space, then to I/O device
double buffering
block of available memory; holes of various size are scattered
throughout memory
Hole
sizes for efficiency (sized to a given process’ needs)
Variable-partition
Allocate the first hole that is big enough
First-fit
Allocate the smallest hole that is big enough; must
search entire list, unless ordered by size
Best-fit:
Allocate the largest hole; must also search entire list
Worst-fit
total memory space exists to
satisfy a request, but it is not contiguous
External Fragmentation
allocated memory may be slightly
larger than requested memory; this size difference is memory
internal to a partition, but not being used
Internal Fragmentation
