2.1.1 Levels of parallelism

We distinguish the following levels of parallelism :

Job :
Full jobs are running completely in parallel on different processors with weak or no interaction between those jobs.
$\longrightarrow$ improved throughput of computer
$\longrightarrow$ shorter real time of jobs,
e.g.: workstation with multiple processors and multitasking.

Program :
Parts of one program are running on multiple processors.
$\longrightarrow$ shorter real time.
e.g.: parallel computer

Instruction :
Parallelization between phases of execution.
$\longrightarrow$ Accelerated execution of the whole instruction.
e.g.: sequential computer / single processor.

Arithmetics, bit level :
Hardware inherent parallelism of integer arithmetics. Bit-wise parallel access but word-wise sequential access and vice versa.
$\longrightarrow$ Less clocks for executing an instruction.
e.g..: superscalar processors, 32/64 bit bus system

The levels of parallelism can be combined.