ASK HN: 1 core for a 16 core VPS server, is it dedicated or shared? | Hacker News Reader

ASK HN: 1 core for a 16 core VPS server, is it dedicated or shared?

1 pointForFreedom6 comments

I was having a discussion with a VPS web host ( a well known web host). I asked them is them about the usage of the core. They said that if I choose a 1 core VPS it will be dedicated to me. To my understanding that cores on a VPS are never reserved for "ONE" user. So if they have 50 different customers would they allot ONE 16 core bare metal box if 1 core is reserved for one customer?

We went on to chat for one hour, and I think they avoided to answer my question or the person on the live chat had no idea what I was asking.

So my question here is if there a bare metal box and the max is 16 core for a VPS server can the web host dedicate 1 core to each user or the core is shared?

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Perhaps they can use processor affinity to put each user in one core ( https://en.wikipedia.org/wiki/Processor_affinity ).

Sometimes this is useful to make single thread programs fasters, because it avoids the necessity to "transfer" the cache form the old core to the new core. ( http://mailinator.blogspot.com.ar/2010/02/how-i-sped-up-my-s... the article is old (2010) but interesting)

I never tried this in a situation like yours, so I don't know if this is useful in your case.

Interesting article from 2010. So what you are saying is that they can dedicate one core to multiple users(who hosts multiple websites) using processor affinity?

>So my question here is if there a bare metal box and the max is 16 core for a VPS server can the web host dedicate 1 core to each user or the core is shared?

Yes, they can dedicate 1 core (or more) to a user. They just pin the VPS processes to specific cores per user.

Xen allows this for example: "vCPU Pinning for guests - You can dedicate a physical cpu to a particular virtual cpu or a set of virtual cpus."

What exactly do you find hard to believe?

That they can assign a core to a particular user. So assume the VPS is a 16 core, according to your statement if they have 16 clients, the web host can allot 16 clients only?

>That they can assign a core to a particular user.

How's that hard to believe? You can even assign a single particular process (e.g. nginx) to a core (or a range of cores) yourself in your own linux laptop.

Assigning a virtual CPU to a physical core is no more difficult with modern supervisors.

>So assume the VPS is a 16 core, according to your statement if they have 16 clients, the web host can allot 16 clients only?

No, they can also allot 1,000 clients, which would then be sharing cores.

But IF they pin each of their clients to a single core, then yes, they can only have up to 16 clients (or less) for a 16-core server.

And they can also combine those two options: allot 4 cores to 4 customers (one per core), and the remaining 12 cores to 20-30 other customers...

[update] I shall post the chat transcript if required.

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