Number of processor cores confusion

[Chris Green]

On Tue, Nov 10, 2020 at 02:59:25PM +0100, Volker Wysk wrote:
> Hi!
> 
> Your answers made me wiser. So I have one socket, with 8 cores and two
> threads per core. 
> 
> This means there are 16 actors working for me. (Even though they might not
> be full replacements für real cores). Not bad. I thought I still had 8. :-)
> 
However, in reality, *very few* things running on your computer ever
use more than one thread/core.  Almost all of the time only one is
being used.

I have only seen a couple of rather specialised bits of code that
manage to use more than one core, one of them was the password security
checking program crack_known_hosts.py, I think I also noticed a static
web site generating program doing it too.

It's difficult to write multi-threaded code so most people don't, the
only (moderately) easy candidates for it are things which do intensive
processor bound things without any I/O (like the above password
cracking and/or image processing programs).  Anything that uses system
libraries and I/O is almost inevitably single threaded.


-- 
Chris Green