chapter 17 - 18 hardwired vs microprogrammed control multithreading multicore computers summary of...

Chapter 17 - 18

• Hardwired vs Microprogrammed Control

• Multithreading

• Multicore Computers

• Summary of Parallel Organizations

• Recap of Course

• Final Exam: Next Thursday- Same time / same place

Hardwired Control

Hard Wired Control

(State machine - Combinational Logic)

Microprogrammed Control

Control Outputs Next Location

Address C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 TRUE FALSE

0 1 0 0 0 0 0 0 0 0 0 1 4

1 0 0 1 0 0 0 0 0 0 0 2 5

2 0 0 0 0 1 0 0 0 0 0 3 6

3 0 0 0 0 0 0 1 0 0 0 0 7

4 0 0 0 0 0 0 0 1 0 0 0 0

5 0 1 0 0 0 0 0 0 0 0 0 0

6 0 0 0 0 0 1 0 0 0 0 0 0

7 0 0 0 1 0 0 0 0 0 0 0 0

8 0 0 0 0 0 0 0 0 0 0 0 0

9 0 0 0 0 0 0 0 0 0 0 0 0

10 0 0 0 0 0 0 0 0 0 0 0 0

Micro-Control Memory

Note: Assume we begin in State A

Sequencer:

Micro-Control

Memory

Definitions of Threads and Processes

• Process: —An instance of program running on computer

• Thread: dispatchable unit of work within process—Includes processor context (which includes the program

counter and stack pointer) and data area for stack—Threads execute sequentially, but are Interruptible

– the processor can turn to another thread

• Thread switch—Switching processor between threads within same

process– Typically less costly than process switch

Implicit and Explicit Multithreading

• Explicit Multithreading is Concurrently executing instructions from different explicit threads— Instructions are Interleaved from different threads on

shared pipelines or executed in Parallel on separate pipelines

• Implicit multithreading is concurrent execution of multiple threads extracted from a single sequential program—Implicit threads are defined statically by the compiler or

dynamically by hardware

Scalar Threading

Multiple Instruction Issue Threading

Parallel Diagram

Multicore Organization Alternatives

Intel x86 Multicore OrganizationCore i7

• Released November 2008

• Speculative pre-fetch for caches

• Simultaneous multi-threading (SMT)— 4 SMT cores, each supporting 4 threads appears as 16 cores

• On chip DDR3 memory controller— Three 8 byte channels (192 bits) giving 32GB/s

• QuickPath Interconnection— Cache coherent point-to-point link— High speed communications between processor chips

– 6.4G transfers per second, 16 bits per transfer– Total bandwidth 25.6GB/s

Intel Core i7 Block Diagram

.3 ns/B !

Intel Core i7

approx 45x45 mm

45 nm feature size

Parallel Processor Architecture Summary

Very Tightly Coupled Tightly Coupled Moderately Coupled

MultiCore Organization(Very tightly Coupled or Single Processor)

Symmetric Multiprocessor (SMP) Organization(Tightly Coupled)

Non-Uniform Memory Access (NUMA) Organization(Moderately Coupled)

Cluster Organization(Loosely Coupled)