Technical data

Glossary
scalar operand: The symbolic expression representing the scalar data
accessed when an operation is executed; for example, the input data or
arguement.
scatter: The process of storing data into memory starting with a base address
plus an offset address; the instruction that performs this action of placing
the data back into memory.
second-order linear recurrence: Two cyclic data dependencies occurring in a
linear function.
speedup ratio: The vector processor performance divided by the scalar
processor performance; indicates how many times faster the computer is
with a vector processor installed than without it.
store: To move data from vector register to memory; for example, the VSTx
command moves the results from the vector register back to memory.
stride: The number of memory locations (bytes) between the starting address
of consecutive vector elements; for example: A vector has a starting address,
a length of 10 elements, and a stride of 4 bytes between the start of each
element.
stripmining: The process of splitting a vector into two or more subvectors,
each of which will fit in a vector register, so each is processed sequentially
by the vector procesor.
sustained megaflops: The average floating-point performance achieved on a
computer during some reference application (or benchmark).
translation buffer: A hardware or software mechanism to remember successive
virtual address translations and virtual page addresses, used to save time
when referencing memory locations on the same memory page.
translation buffer miss: An occurrence where the processor cannot translate
the virtual address using the current contents of the translation buffer.
In such a case, the processor is forced to load new information into the
translation buffer to furnish the address.
unknown dependency: An unclear relationship between multiple references
to a memory location; a relationship in which the final value of the location
may or may not depend on serial execution of the code involved.
vector: A data structure composed of scalar elements with the same data type
and organized as a simple linear sequence.
Glossary–5