Re: [Xen-devel] [PATCH] serialize suspend-resume process

[BVK Chaitanya <bayapuneni_chaitanya@xxxxxxxxxxxx>]

Keir Fraser wrote:
> On 31/7/08 16:27, "BVK Chaitanya" <bayapuneni_chaitanya@xxxxxxxxxxxx> wrote:
>
> > It is doing a busy-wait loop till suspend-resume cycle completes, if
> > any.  I found that it may go more than 25 msec sometimes.
> It's not a busy-wait loop. As long as shutdown_state does not change under
> its feet, it will complete in no more than two iterations.
Yep, my mistake :-(


I still have a concern, but it may not be important for xen-3.3 as of 
now.  Let me explain:
Dom0 can trigger a suspend-resume cycle and can wait for suspended 
notification back through event channel (and subscribe domctl).  When 
dom0 is done with its checkpoint-ing or any work it can resume the domU.
But resuming the domU doesn't complete suspend-resume cycle. 
Suspend-resume cycle is completed only after domU completes the 
xenbus_suspend_cancel function (I saw it taking more than 25msec.) 
Suspend requests sent during this suspend-cancel time are _lost_.
If we assume dom0 shouldn't send suspend requests during suspend-cancel, 
there must be some way for dom0 to know when suspend-cancel is 
completed.  AFAIK this doesn't exists in the current state.
Does it clarify my concern?  Shall i bring this issue back after xen-3.3 
is release work is done?
--
bvk-chaitanya

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