On 02/09/2018 08:15 PM, Dr. David Alan Gilbert wrote:
* Wei Wang (address@hidden) wrote:
This patch adds a timer to limit the time that host waits for the free
page hints reported by the guest. Users can specify the time in ms via
"free-page-wait-time" command line option. If a user doesn't specify a
time, host waits till the guest finishes reporting all the free page
hints. The policy (wait for all the free page hints to be reported or
use a time limit) is determined by the orchestration layer.
That's kind of a get-out; but there's at least two problems:
a) With a timeout of 0 (the default) we might hang forever waiting
for the guest; broken guests are just too common, we can't do
that.
b) Even if we were going to do that, you'd have to make sure that
migrate_cancel provided a way out.
c) How does that work during a savevm snapshot or when the guest is
stopped?
d) OK, the timer gives us some safety (except c); but how does the
orchestration layer ever come up with a 'safe' value for it?
Unless we can suggest a safe value that the orchestration layer
can use, or a way they can work it out, then they just wont use
it.
Hi Dave,
Sorry for my late response. Please see below:
a) I think people would just kill the guest if it is broken. We can also
change the default timeout value, for example 1 second, which is enough for
the free page reporting.