* Denis V. Lunev (d...@openvz.org) wrote: > On 10/07/2015 06:05 PM, Eric Blake wrote: > >On 10/07/2015 12:20 AM, Denis V. Lunev wrote: > >>From: Igor Redko <red...@virtuozzo.com> > >> > >>This patch declares a new migration capability that allows > >>to distinguish between true migration and the test. > >> > >>An alternative is using a custom URI but in this case the > >>following problems should be solved: > >>1/ QEMUFile abstraction hides the real transport type > >>2/ We must be ensured that VM will not be stopped due to > >>“successful migration” > >> > >>Possible solutions: > >>1/ Using global variable analogous to > >>s->enabled_capabilities[MIGRATION_CAPABILITY_TEST_ONLY] that > >>will be initialized according to the migration type at the > >>beginning of the migration process > >>2/ Additional hook, presence of implementation of which allows > >>to decide whether the migration is true > >> > >Do we want to name the capability 'x-test-only', since this series is > >experimental, to make it obvious that production code should not rely on it? > > > actually the answer is 'no'. This feature is designated for production. > May be the name is just wrong or description is bad :) Yep, I know this > for sure... > > OK. The idea of this feature is to estimate efforts required to > perform migration and downtime during that migration. > This estimate is necessary to decide whether we are able > to automatically move the VM from one node (loaded) to > different node with less load.
Yes, this is the use we had also been considering. > Should we rename 'test' to 'estimate' or something like that > to make the situation clearer? > > On the other hand this 'estimate' state would be very useful > for testing that is why I have proposed this code to John. > At least we were able to catch recently fixed hang on migration > cancel (in pipeline already). > > I am completely open to any idea. I can see how 'test' might confuse with other test things; but I'm not too fussy about the name. I was thinking 'null' if it was a transport name. Dave > > > >>+++ b/qapi-schema.json > >>@@ -540,11 +540,14 @@ > >> # @auto-converge: If enabled, QEMU will automatically throttle down the > >> guest > >> # to speed up convergence of RAM migration. (since 1.6) > >> # > >>+# @test-only: If enabled, QEMU instead of migrating will estimate migration > >>+# time basing on given downtime and current dirty page rate > >If we do decide to add this to mainline, it would need 'since 2.5' (or > >whatever version) documentation. > > > Sure! > -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK