PIPELINING

·         In computing, pipelining is a set of data processing elements connected in series therefore the output of one element is the input of the next element.

·         The above statement means the microprocessor begins to execute second instruction before the first instruction complete.

·         The pipeline is divided into segments and each segment can execute its operation concurrently with the other segments.

·         That is , when a segment complete an operation, it passes the result to the next segment in pipeline & fetches the next operation from the preceding segment.

·         For a microprocessor that without the pipelining, the second operation will only started when the first operation fully completed.

·         Therefore, the microprocessor which with the pipelining will be more efficient and faster compared to the one without pipelining…

·         Below is a diagram of microprocessor with a pipelining…

·         for 4 loads:

Ø  8/3.5 or (4(4)/(4+3))=2.3

·         Non-stop:

Ø  4n/(n+3)=4(16)/(16+3)=3.347≈4 stages

·         Although the pipelining initially formerly a feature only of high-performance & RISC-based microprocessor, now is commonly in microprocessor used in personal computers. (For examples,  Intel’s Pentium uses pipelining to execute as many as six instructions simultaneously….)

·         Besides, pipelining also called pipeline processing.

·         Eg:

Ø  DRAM:

o   Memory loads the requested memory contents into small cache composed of SRAM and then immediately begins fetching the next memory.

o   Creates two stages:

§  Stage1: data is read from or written to the SRAM

§  Stage2:data is read from or written to memory

Ø  DRAM(c’td):

o   Usually combine with another performance technique called burst mode

o   And the two techniques together called pipeline burst cache

·         MIPS Pipelining:

o   Five stages (one step per stage):

o   IF: instruction fetch from memory

o   ID: instruction decode and register read

o   EX: execute operation or calculate address

o   MEM: access memory operand

o   WB: write result back to register

Chong Lee Man
B031210367