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What is the difference between a CPU and a vCPU?
Some VPSs quote a number of CPUs and others quote vCPUs?
How does the vCPU differ from the CPU? Do they refer to what a VPS is guaranteed,or what a VPS is guaranteed if they are available?
Do they have their CPU equivalents, eg Amazon mention in the past that a CPU was the equivalent of 1.7GHz Opteron or some other AMD CPU.
Comments
a CPU is a real physical thing. vCPU is a marketing term used to describe part of a CPU (normally a core or a thread in the case of hyperthreaded CPUs).
Generally, VPS hosts around here mean vCPUs. There are some (like AbusiveCores) that allocate a whole core to you, and you can use it around the clock. Besides that, most hosts enforce a shared policy.
Allocation of threads/cores and such.
afaik no virt platform is capable of assigning a physical socket via pass through to a VPS, as such the host system allows the guest access to a core or number of cores, with or without pinning it is still essentially a virtual core in every instance so its just terminology, vCPU is the correct terminology, but in reality.... no difference.
Dedicated servers give you your own CPU with it's cores/threads allocated fully to you. Use away!
Most commonly 1/2 CPU = vCPU
AbusiveCores doesn't really give you a whole core. You get a single thread (1/2 a physical core) on a hyper-threaded processor.
Don't get me wrong, I'm not saying that's bad for what it is since maxing out a single thread is still more than most providers will let you do, but I do think the service's name is a tiny bit deceptive.
Oh, I did not know that... Thanks for clearing that up. :-)
This. Some people say CPU, some say vCPU. At the end of the day, they are all "virtual" cores on a VPS.
This is very true but its also a name it would then have to be absuive thread and that does not sound as good.
vCPU is kind of meaningless with hyperthreading so yea it's more about marketing than anything else.
You are not necessarily even getting 1/2 a core. Logically yes but hyperthreading isn't that good. If you don't believe me just look at pricing from dedicated server providers. If they do charge a premium for hyperthreading CPU vs non-hyper, it's usually minimal.
The minimum # of vCPU's someone should get on a hyperthreaded CPU to give some idea what performance they could expect is 2. If it's only one then I think it will have a lot to do with what your neighbours are doing.
Your neighbor always matter a lot, because the L3 cache of the whole CPU is shared. And a CPU without cache is worthless in terms of performance.