Pipelining Technology and parallel technology

Two major breakthroughs in processor history: Pipelining allows the processor to execute multiple instructions at the same time, and parallel technology allows the processor to execute multiple threads at the same time.

Recently looking at Wcet (worst case execution time, worst execution times)

In the software system, WCET includes three aspects: one is the multi-core processor when multitasking to the operation of shared variables, and the second is a distributed system Master machine query to select the time spent slave machine, the third is the network request and the time spent in transmitting data. Of course, the most time-consuming network transmission.

In an embedded system, the execution time of a thread includes the trigger to response time of the event, the waiting time of the request processor, the processing time of the data, the time the device was requested, and the time the data was written. This is only a single-tasking scenario and does not take into account the interruption caused by multitasking.

The processing power of a multi-core processor means that a single core can execute only one command at a time when the instruction is executed on a multiprocessor, but a thread is dynamic and often consists of multiple instructions, so a thread is done together on multiple cores.

Inspired by AMD's first launch of the 64-bit processor, Intel recalls "Multicore" and launched the Pentium D and Pentium IV Extreme Edition 840, which encapsulates dual-core in April 2005, from which the processor entered the multicore era. But multicore before, in 1985 when Intel introduced 80486, the chip only appeared pipeline technology, breaking the processor can only handle single instruction technical barriers.

Reason:

Compared to 80486 and 80386, the number of processors is 32 bits, and the bus bit width is 32 bits. But the number of transistors also from 275,000 is coming to 1.25 million, processing instruction speed increased, clock frequency also increased from 25MHz to 33MHz, 40MHz, 50MHz, 66MHz, processor size also greatly reduced (reduced to 1 micron process).