Does the number of Cores = the number of kernel threads?

Question

"Does the number of Cores = the number of kernel threads?"

While we were studying for the midterm of Operating System, few people started to ask this question. It seems that the textbook, "Operating System Concepts (by Abraham Silberschatz, Peter B. Galvin, Greg Gagne)", doesn't explain this clearly enough. Therefore, I started to find out the answer on the internet. Here comes my study.

Answer

NO! The maximum number of the kernel threads can up to around 15,000 on a general machine. And, the number of the cores mostly are round 2~4. It means that "one core can run more than 2 kernel threads in the same time", which is called "Hyper-Threading".

Reference

• http://superuser.com/questions/347407/number-of-kernel-threads-cores
• http://superuser.com/questions/340918/what-does-thread-mean-as-related-to-cpus
• http://stackoverflow.com/questions/344203/maximum-number-of-threads-per-process-in-linux/344292#344292