A question about "suspend-record frame number"

A question about "suspend-record frame number"

[David Knight]

Dear friends:

in xc_domain_save.c, there is a suspend-record frame number which is
stored in the first vcpu's edx register. What the major use of this
"suspend-record frame number". Why this frame number is store there?

I want to replace the suspend_and_state with xc_domain_shutdown because
the former one is much slower. But after I replaced the funcion, that
frame number was lost. What if I ignore the error and omit the
corresponding code in xc_domain_restore.c?? Thanks.

Re: A question about "suspend-record frame number"

[Keir Fraser]

The suspend-record provides information from the suspended guest to
xc_domain_save/restore in the toolstack, and then back to the restored
guest. You can't just do xc_domain_shutdown() from the tools because a PV
guest has to prepare itself for save/restore, and it wouldn't get the chance
to do that in that case. The suspend_and_state() got sped up a lot for
guests which support suspend notification via an event channel (rather than
going via xenstore, which is 100s of milliseconds slower typically).

 -- Keir


On 21/02/2009 08:42, "David Knight" <dongwei.net@pku.edu.cn> wrote:

> Dear friends:
> 
> in xc_domain_save.c, there is a suspend-record frame number which is
> stored in the first vcpu's edx register. What the major use of this
> "suspend-record frame number". Why this frame number is store there?
> 
> I want to replace the suspend_and_state with xc_domain_shutdown because
> the former one is much slower. But after I replaced the funcion, that
> frame number was lost. What if I ignore the error and omit the
> corresponding code in xc_domain_restore.c?? Thanks.
> 
> 
> 
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