CPU Architecture fundamental

Terminology

• Processor: the physical chip that plugs into a socket on the system or processor board and contains one or more CPUs implemented as cores or hardware threads.

• Core: an independent CPU instance on a multicore processor. The use of cores is a way to scale processors, called chip-level multiprocessing (CMP).

• Hardware thread: a CPU architecture that supports executing multiple threads in parallel on a single core (including Intel’s Hyper-Threading Technology), where each thread is an independent CPU instance. One name for this scaling approach is multithreading.

• CPU instruction: a single CPU operation, from its instruction set. There are instructions for arithmetic operations, memory I/O, and control logic.

• Logical CPU: also called a virtual processor (vCPU), an operating system CPU instance (a schedulable CPU entity). This may be implemented by the processor as a hardware thread (in which case it may also be called a virtual core), a core, or a single-core processor.

• Scheduler: the kernel subsystem that assigns threads to run on CPUs.

• Run queue: a queue of runnable threads that are waiting to be serviced by CPUs. For Solaris, it is often called a dispatcher queue.

Example

Intel® Core™ i7-5557U Processor on Macbook pro: 2 cores, 4 threads

sysctl -n hw.ncpu # = 4
sysctl -n hw.physicalcpu # = 2
sysctl -n hw.logicalcpu # = 4

Reference

Chapter 6: CPUs in http://www.brendangregg.com/sysperfbook.html