How to use all CPU power for VM

[bakhvalov.anton]

Hi everyone.
We use proxmox 4.4 for 4 VMs
- MS SQL
- PDC server
- FILESERVER
- OPENVPN server

Host server has 32 cpu's
VMs use them
- SQL - 20 proc
- PDC - 2 proc
- FILESERV - 4 proc
- openvpn - 2 proc

When SQL server is at 100% load I monitor that PVE uses only 50-60%

How to give maximum power to VM (SQL)? (80-90%). All other 3 VM use 2-5% or less.

Thanks in advice.

 

[wolfgang]

Hi,

If you have a SQL VM with 20 procs (vcores) and your system has 32 logical cores.
Then you can max occupy 60% of the system.

A process can never take more than one logical core.
If you like more system workload you have to increase the vcores of the VM

 

[bakhvalov.anton]

I'll try to take some cores from DC and Fileserver

What is better - 2 sockets 10 cores or 1 socket 20 cores or 5 sockets 4 cores ?
Or it doesn't matter?

 

[wolfgang]

You should use the same architecture as you have on your physical machine.
So if you have a 2 way (Socket) with each socked has16 cores, you should go for 2 * 10 cores.
The reason is then your VM is aware of NUMA and will try to allocate the memory to the corresponding core.

 

[tschanness]

You could also give the SQL Server 26-30 Cores and not take away from other VMs. CPU can be overprovisioned and if your other VMs don't have a high utilisation.

 

[wolfgang]

Yes, you can be overprovisioned.
But I would give them max 28 vcpus because a context switch is a costly thing.

 

[bakhvalov.anton]

I'll try to make this config for node
- SQL 2*13 (26 cores)
- PDC 1*2 (2 cores)
- FILESERV (1*2 cores)
2 cores - reserved (for proxmox?)

should i switch numa=1 or not?

how to allocate cpuunits? please tell best practice?

 

[wolfgang]

2 cores - reserved (for proxmox?)

Proxmox need not exlusive core.

should i switch numa=1 or not?

If you have NUMA Host then you should activate numa on the SQL VM.

For cpuunits see 10.2.4 "Resource Limits"
https://pve.proxmox.com/pve-docs/pve-admin-guide.html#qm_virtual_machines_settings