Question about the current vcpu.

Question about the current vcpu.

[p z]

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Hi all,

 There is a macro current which may mean to get the current vcpu
information.

 But  the physical machine may be multi-core ,thus there may be two or more
vcpus running  in parallel on different cores.Then which vcpu is the
current? How should  I understand the current vcpu please?

 Thanks.


Cheer,
-- 
zp

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Re: Question about the current vcpu.

[Jeremy Fitzhardinge]

p z wrote:
>  But  the physical machine may be multi-core ,thus there may be two or 
> more vcpus running  in parallel on different cores.Then which vcpu is 
> the current? How should  I understand the current vcpu please? 

"current" returns the vcpu currently running on this physical cpu (ie, 
the one that's executing "current" itself).   It will return different 
results for each pcpu at a given instant, and will return different 
values for a given pcpu over time as different vcpus are scheduled on itnb.

    J

Re: Question about the current vcpu.

[Zhiyuan Shao]

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Hi,

Actually, defined by Credit scheduler, each PCPU (physical CPU, if you run Xen on a multi-core machine, you get multiple PCPUs) has its own runqueue, and its own current vcpu as well.
The PCPUs of the system makes their own scheduling decisions independently. 

Best,


2009-03-30 



Zhiyuan Shao 



发件人： p z 
发送时间： 2009-03-28  09:38:16 
收件人： xen-devel@lists.xensource.com 
抄送： 
主题： [Xen-devel] Question about the current vcpu. 
 
Hi all,

 There is a macro current which may mean to get the current vcpu information.

 But  the physical machine may be multi-core ,thus there may be two or more vcpus running  in parallel on different cores.Then which vcpu is the current? How should  I understand the current vcpu please? 
  
 Thanks.


Cheer,
-- 
zp

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