Re: [PATCH] serialize suspend-resume process

[BVK Chaitanya <bayapuneni_chaitanya@symantec.com>]

Keir Fraser wrote:
> 
> On 31/7/08 16:27, "BVK Chaitanya" <bayapuneni_chaitanya@symantec.com> 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