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Re: [Xen-users] VCPU amount



On Thu, Mar 26, 2009 at 10:26 PM, Vladislav Karpenko
<vladislav@xxxxxxxxxxxxxx> wrote:
>>> Terminal:
>>> vcpus=6
>>> cpus='1-7' #0-core dom0
>>> cpu_weight=65000
>>> cpu_cap=600
>>>
>>> Database/Mail is
>>> vcpus=1
>>> cpus='1-7' #0-core dom0
>>> cpu_weight=256
>>> cpu_cap=100
>>>
>>
>> That config would essentiallay mean that 6 core would be almost
>> dedicated (due to very high cpu_weight) to terminal server. This means
>> that under high load dom0 will use one core (if you pin and limit dom0
>> CPU like I do), terminal server will occupy 6 cores, and 1 core is
>> shared between database/mail. If this is what you want then above
>> config is correct.
>
> But if Terminal server is idle and have some piece of cpu resources could
> other domu use this piece with that config?

Yes, since you set all to use same physical cpus/core (1-7).
However due to high cpu_weight don't be surprised if you see terminal
server dominates those 6 cores (since in Windows it's quite common to
have almost-constant high cpu load without you knowing why, but that's
another issue), so that the other domUs can only fight over one core.

> cpu=100 means that rest of domu can load max one core from pool per domU

cpu_cap=100 means that particular domU can have a maximum total load
equivalent to one physical CPU. The default setting is 0 (which means
unlimited), but if you allocate only 1 vcpu then specifiying
cpu_cap=0, or cpu_cap=100, or not specify it at all will have the same
effect.

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