[PVE-User] cores and threads Re: pve-user Digest, Vol 109, Issue 13

[Michael Peele]

The common thinking is do not assign more than N-1 cores to a VM (to allow
the VM to have a core).
If you have multiple VMs, then it will really vary a lot on what you can
assign.  You might try giving the high CPU one 4 cores, the moderate 3, and
the low ones 2 each.  Yes, that is 9.  You can oversubscribe, just don't
give one VM too many (N-1; in your case 7, though only 4 are real, which
makes it more complex.)

It is very complex with real cores, hyperthread cores, CPU load, memory
load, etc.

If a VM is maxing out, give it another core, if you want.  If a VM is very
low on CPU, maybe remove a core, but if it never uses much, it won't
matter.  Assigning cores is more about CPU prioritization and VM
prioritization.

Maybe you determine that DNS, while  normally having low usage, needs to
take some random DoS, so you give DNS 7 cores even though it normally only
needs 1.  Maybe the VM that has 100% CPU usage on 2 cores is a "low"
priority test system, so you won't give it more than 2 just because.

Thus, nobody can tell you what your combination of supply (ram, CPU, disk,
network), demand, and priorities are.

Regards.



On Sun, Apr 16, 2017 at 6:00 AM, <pve-user-request at pve.proxmox.com> wrote:

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>    1. Re: cores and threads (Miguel González)
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> ----------------------------------------------------------------------
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> Message: 1
> Date: Sat, 15 Apr 2017 22:01:32 +0200
> From: Miguel González <miguel_3_gonzalez at yahoo.es>
> To: "pve-user at pve.proxmox.com" <pve-user at pve.proxmox.com>
> Subject: Re: [PVE-User] cores and threads
> Message-ID: <c0336d43-8f5c-abb8-041c-652a7c0953bd at yahoo.es>
> Content-Type: text/plain; charset=utf-8
>
> No one can help me out?
>
>
> On 04/13/17 4:55 PM, Miguel González wrote:
> > Hi,
> >
> >   I have a Proxmox 4 host running Intel Xeon W3520 with 4 cores and 8
> > threads with 32 gb of RAM. This host has 5 VMs.
> >
> >   Two VMs has quite heavy CPU usage (two web servers), another one quite
> > moderate (email server, but only with a few accounts) and two DNS
> > servers with low usage.
> >
> >   How many sockets and cores can I allocate?
> >
> >   Can I enable NUMA? I get:
> >
> >   numactl --hardware
> > available: 1 nodes (0)
> > node 0 cpus: 0 1 2 3 4 5 6 7
> > node 0 size: 32165 MB
> > node 0 free: 164 MB
> > node distances:
> > node   0
> >   0:  10
> >
> >
> >   I have searched on Google and the information is not very clear about
> > how many sockets and cores I can set in a VM.
> >
> >   Thanks!
> >
> >   Miguel
> >
> >
> >
> >
>
>
>
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