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RE: [Xen-ia64-devel] Question about migration


  • To: "Kouya Shimura" <kouya@xxxxxxxxxxxxxx>
  • From: "Xu, Anthony" <anthony.xu@xxxxxxxxx>
  • Date: Wed, 13 Feb 2008 12:22:59 +0800
  • Cc: xen-ia64-devel <xen-ia64-devel@xxxxxxxxxxxxxxxxxxx>
  • Delivery-date: Tue, 12 Feb 2008 20:26:26 -0800
  • List-id: Discussion of the ia64 port of Xen <xen-ia64-devel.lists.xensource.com>
  • Thread-index: Acht98ClbuIJYw8tSfeOnD3hwu8QWQAADXVA
  • Thread-topic: [Xen-ia64-devel] Question about migration

Kouya Shimura wrote:
> Xu, Anthony writes:
>> You are right here, if migration happens in the same machine,
>> How about migrate to another physical machine?
>> There may be different ITC value in different machine.
> 
> I tried it. Actually far ITC jumping has occurred.
> This could happen in domain save/restore also.
> 
> But the monotonicity of system time (gettimeofday) is guaranteed.
> that seems to be done in:
> time_resume()@linux-2.6.18-xen.hg/arch/ia64/kernel/time.c.

If application uses gettimeofday , there is no issue.
While if application read ITC directly, (in theory, it can), we have
trouble.

Anthony


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