Well, suppose then we have an CPU system such as:

Thread(s) per core $\equiv t$ : 4

Core(s) per socket $\equiv c$: 4

Socket(s) $\equiv s$: 1

Then, we must to perform a simple calculation such as: $ 4 \cdot 4 \cdot 1 = 16 $

Therefore, in general we have:

$$ T = t\cdot c \cdot s \tag{1}$$

I guess that the equation $(1)$ gives you then the total number of threads which your system can handle simultaneously.

On the other hand, consider the figure, of windows task manager, in the following:

enter image description here

In the red box we clearly see the number of "Threads". So I would like to know:

What is the difference between the number given by formula $(1)$ and the number given by windows task manager?

  • $\begingroup$ I am not an expert on the topic, but it's possible this question is a bit too specific to Windows Task Manager, rather than computer architecture in general. $\endgroup$ – 6005 Jul 10 '20 at 16:21

There are two kind of threads, hardware and software threads. The threads number shown in red box is the number of software threads. The threads calculated above(16) is the number of hardware threads.

A processor consists of multiple functional blocks like, register sets, integer ALU, floating point ALU, instruction decoder, instruction fetch units... In a pipelined processor supporting superscalar architecture (also known as hyperthreading or HT on Intel processors), instructions from multiple software threads can be in different phase of execution at the same point of time. The number of software threads instruction sequence which can be concurrently executing in a single processor core is defined by the hardware and are known as logical threads. Look at SMT threads for more clarity.

The number of threads shown is red box or software threads are the total number spawn threads. At most, 16 of them can be executing at the same point of time on the specified hardware. Operating system schedule software threads (in 1000's) on the available processors using some scheduling policy.


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