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RE: [Xen-devel] netif_suspend / resume

  • To: "Jacob Gorm Hansen" <jacobg@xxxxxxx>, <Xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: "Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>
  • Date: Thu, 19 May 2005 08:29:46 +0100
  • Delivery-date: Thu, 19 May 2005 07:29:32 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AcVcJILuRtJkxYFLRMKshR03ZmsGkAAGwzqQ
  • Thread-topic: [Xen-devel] netif_suspend / resume


> does netif_suspend() have any side effects with regards to 
> the state of memory pages that are currently awaiting I/O?
> It seems to basically unbind from the event channels for the 
> vifs, does that guarantee that Xen or the driver domain will 
> not decide to flip any of the client domain's pages after 
> this point? How does the client domain reclaim outstanding 
> sbks during/after a suspend?

The guest keeps its own shadow copy of the state as regards which pfn's
it has queued as {free, rx, tx}bufs. After a resume it 'gathers' those
pages and requeues the free and tx bufs to the new backend. 

We currently junk any outstanding rxbufs, but in reality there almost
never are any as the vif interrupt will be serviced before the suspend
thread gets to run. When we switch over to grant tables we'll be able to
process these on the destination too, as we'll know the memory has been
syncronized. It won't make difference, though.


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