What is socket, core, threads, CPU?

Question

I am currently volunteering to learn about linux servers and also I am interested in learning about cluster computing techniques.

In this lab, they have a small cluster with one head node and two compute nodes.

When I tried the lscpu command on head node, compute node1,node2. Click the link to view the details.

CPUs - 24 in head, computenode1 and computenode2. Is it referring to 24 physical CPUs in the motherboard?

Sockets - 2 in head, computenode1 and computenode2.Can anyone explain it?

Cores per socket - 6 in head, computenode1 and computenode2.Can anyone explain it?

Threads per core - 2 in head, computenode1 and computenode2.Can anyone explain it?

Solution

A socket is the physical socket where the physical CPU capsules are placed. A normal PC only have one socket.

Cores are the number of CPU-cores per CPU capsule. A modern standard CPU for a standard PC usually have two or four cores.

And some CPUs can run more than one parallel thread per CPU-core. Intel (the most common CPU manufacturer for standard PCs) have either one or two threads per core depending on CPU model.

If you multiply the number of socket, cores and threads, i.e. 2*6*2, then you get the number of "CPUs": 24. These aren't real CPUs, but the number of possible parallel threads of execution your system can do.

Just the fact that you have 6 cores is a sign you have a high-end workstation or server computer. The fact that you have two sockets makes it a very high-end computer. Usually not even high-end workstations have that these days, only servers.

Comments

[Kyslik]

If you really want to learn, drop using any other OS and just stick to Linux. You will learn quicker. Good luck.

[Peter Cordes]

Related: Is having multiple cores in a CPU for running multiple threads/processes at once, or for instruction-level parallelism? re: "core" vs. "cpu" as synonyms or not.

[Shengmin Zhao]

Refer to: forum.huawei.com/enterprise/en/what-is-socket-core-threads-c‌​pu/… What is socket, core, threads, CPU?

[bioinforesearch]

Sockets - 2 in head, computenode1 and computenode2. (Each of the nodes have 2 physical socket in them)

[bioinforesearch]

Thanks for your simple statements. It makes sense to me now.

[bioinforesearch]

from this "less /proc/cpuinfo", I could see the model name for all the 3 nodes (model name : Intel(R) Xeon(R) CPU X5650 @ 2.67GHz). So this server has two physical sockets. Each socket has a CPU. Each CPU has 6 cores in them. Each cores has two threads in them

[bioinforesearch]

I tried this command "less /proc/cpuinfo"[1]. I have just took screenshot of processor 0 and processor 23 (total 24). What is sibling? what does the cpu cores : 6 refers to? Thanks in advance [1]: i.stack.imgur.com/59MQ0.png

[Eugene]

The thread is closed but this answer is worth an upvote.

[Peter Cordes]

Example: typical terminology is 6c12t, which means 6 physical cores, 12 total logical cores (aka hardware threads). Thus 2 logical per physical, i.e. 2-way SMT (such as Intel's HyperThreading). That can be applied to a whole system, or to a "package" (a physical thing which goes into one socket). i.e. you could have two 8c16t Xeons in a system for a total of 16c32t. You would usually not apply this across a cluster, since that implies separate systems, not one huge one with coherent shared memory that can run many threads.

[variable]

Where can I check the thread count please?