Hi Ian,
Fri, 9 May 2008 13:07:31 +0100, "Ian Pratt" wrote:
>> >Hi Kanno,
>> > We have tried cpus="^1" in the past. For we want to drop only CPU1
>> >no matter how many CPUs are on the machine. The result shows: CPU1 can
>> >still be used by HVM and all the VCPU's affinity are "any cpu".
>> > So, do you think this setting is available? Or do we need some more
>> >comments on this? Thanks!
>>
>> Hi Zhang,
>>
>> I think that a purpose to set "cpus" is to confine CPUs which VCPUs run
>> to a CPU or some CPUs. If there are many CPUs on a machine, I think
>> that we should avoid the setting for performance.
>
>The "^1" syntax is quite useful if you're trying to reserve a CPU for
>use by another domain e.g. domain0, but don't want to otherwise restrict
>the guest.
"cpus" is parsed from left side, and the "^1" negates the values which
was already parsed. So "0-3,^1,1" and "0-3" are equivalent.
The parsing of "cpus" cannot handle "negation" from a beginning because
there is not a value to negate.
But, I'm thinking that I want to implement Zhang's demand since I get
your comment. So I have idea as follows.
cpus = "0:,^1"
The "0:" means "0 or later". How about it?
>We need to be able to deal with setting the affinity mask for a domain
>(that is replicated to all VCPUs) as for individual VCPUs. I assume your
>patch doesn't change the behaviour of the former?
Could you look at the following changest?
http://xenbits.xensource.com/xen-unstable.hg/rev/5c3df1bded82
>BTW, it would also be nice to be able to specify CPUs by
>node.socket.core.thread as opposed to just enumerated CPU number. It
>should be possible to omit unused levels of the hierarchy, e.g. "0.3"
>could be used to refer to the 4th core of the first socket on a dual
>socket quad core machine.
>
>If you're looking for further improvements in this area, enable CPU
>groups to be defined and then allow domains/VCPUs to be assigned to a
>group.
I got interest for your suggestion. Let me think for the time being.
Best regards,
Kan
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