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kich254
Enthusiast
Enthusiast

Processor allocation best practice.

Hi Y'all,

I'd like to know which would be the best way to allocate the processor resource for VMs. I've got Windows Server 2012 R2, Windows 10 64 bit, Windows 7 64 bit and Windows XP Professional 32 bit in my VMware Workstation Pro. The Host processor is an Intel Core i5-8250U Processor with 12Gb RAM. Advice on RAM allocation for each VM would be nice.

Thanks

8 Replies
wila
Immortal
Immortal

Hi,

A rule of thumb would be to set no more than 2 CPU cores per VM.

It depends a bit on your usage, but I would suggest to start at 1 vCPU for  example for the Windows XP VM and 2 vCPUs for the rest.

You could go to 3 vCPUs in for example the 2012 R2 server if you're running something in there that can actually use those extra threads.

Setting any VM to 4 vCPUs (or more) is not recommended as you would end up starving the host and get random lockups.

--

Wil

| Author of Vimalin. The virtual machine Backup app for VMware Fusion, VMware Workstation and Player |
| More info at vimalin.com | Twitter @wilva
kich254
Enthusiast
Enthusiast

My thoughts exactly:) Another Q: say i set them as you've suggested i.e Server 3vCPUs, Windows 10 & 7 2vCPUs each and XP 1 vCPU, would i be able to run all VMs simultaneously?

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wila
Immortal
Immortal

Hi,

Running all 4 VMs simultaneously could work, but you might have to tweak a bit.

The total of RAM assignment should not be more than about 8GB.

Reason being that there's additional overheads and if you enable 3D on your virtual graphics cards then the RAM those take will also be deducted from your total available 12G of RAM.

That's certainly do-able as I tend to keep RAM allocations on most VMs at 2GB or below that.

Depending on workload you can then tweak them.

--

Wil

| Author of Vimalin. The virtual machine Backup app for VMware Fusion, VMware Workstation and Player |
| More info at vimalin.com | Twitter @wilva
kich254
Enthusiast
Enthusiast

For RAM allocation i'll go with; Server 3Gb, Windows 10 and 7 2Gb each and XP 1Gb. so that's well within ur recommended 8Gb Max:)

But as for running all VMs based on the cores wouldn't it mean that the host is "deprived' since it 8 cores(i.e Server 3 vCPUs, Win10 and 7 2 vCPUs each and XP 1 vCPU) running and the processor is a 4 core? or is this where threading comes in or what happens?

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wila
Immortal
Immortal

Hi,

You can normally over provision the total number of virtual CPU's.

In other words, the total number of virtual CPU's running can be higher as the total number of physical CPU's available.

As long as the CPU scheduler has enough room to work with that should be fine.

So it depends on things like the actual workload in the guests.

If OTOH you have a VM with 4vCPU's or more then the chances of the CPU scheduler being able to schedule the CPU's of all your guests becomes very small and lockups will happen regardless of workload.

So I think you are fine, but it really is a matter of test and try and see what will work with your host CPU.

There's also the host OS to take into account as well.

--

Wil

| Author of Vimalin. The virtual machine Backup app for VMware Fusion, VMware Workstation and Player |
| More info at vimalin.com | Twitter @wilva
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kich254
Enthusiast
Enthusiast

Ok. The physical processor is just the one i5 8250u. So you are saying i can have more vCPUs than the 4 core and 8 Threads of the main processor?

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wila
Immortal
Immortal

Hi,

Yes, that's correct.

The vCPU's are scheduled based on need.

They are not taking away a CPU core or thread exclusively for that VM, so it is indeed possible to run more vCPU's simultaneously as there are physical CPU's available at the host level.

Mind you that a hosted product such as VMware Workstation is dependent on the host OS it is running under and as such cannot scale as well as a hypervisor based product such as VMware vSphere. On vSphere it is not uncommon to see a 3:1 overprovisioning (IOW 3x number of actual CPU's), on Workstation that will be closer to 1:1, but you can certainly have more vCPU's running as available in your host.

--

Wil

| Author of Vimalin. The virtual machine Backup app for VMware Fusion, VMware Workstation and Player |
| More info at vimalin.com | Twitter @wilva
kich254
Enthusiast
Enthusiast

I see. I know more now than before! Thanks mateSmiley Happy

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