AWS EC2: number of processor cores available per instance

Question

I recently installed an instance (m4.4xlarge).

when I execute the lscpu command, the output looks something like this:

 CPU op-mode(s): 32-bit, 64-bit Byte Order: Little Endian CPU(s): 16 On-line CPU(s) list: 0-15 Thread(s) per core: 2 Core(s) per socket: 8 CPU socket(s): 1 . . . 

Does this mean that you can use only 8 cores?

If so, what are the other processors for?

Answer 1

m4.4xlarge instances have 16 logical processors, so it looks like your EC2 instance reports this as the only socket with 1 physical processor with 8 cores. Each core can execute two threads at the same time (Intel Hyperthreading technology), therefore each core is represented as two logical processors.

 CPU(s): 16 <- logical CPUs (Threads per core * Cores per socket) On-line CPU(s) list: 0-15 Thread(s) per core: 2 <- Each core has hyperthreading and presents itself as two logical CPUs Core(s) per socket: 8 <- Instance sees it has 8-core physical CPU per socket CPU socket(s): 1 <- Instance sees it has 1 physical CPU