Hello, Following on from the discussion about creating savevm/loadvm QMP equivalents. I decided to take the advice given that we should use external snapshots. However reverting to a snapshot currently requires QEMU to be restarted with "-incoming". Restarting QEMU requires a fair bit of book keeping to be done by the management application and may take measurably more time.
Also to quote the previous discussion: >>> > Then you could just use the regular migrate QMP commands for loading >>> > and saving snapshots. Might need a little extra work on the incoming >>> > side, since we need to be able to load snapshots, despite QEMU not >>> > being started with '-incoming defer', but might still be doable ? >>> > This would theoretically give us progress monitoring, cancellation, >>> > etc for free. >>> >>> What actually stops this working other than the sanity check in >>> migrate_incoming ? >> >> No idea really - not looked closely at the code implications. > > It would be a plus for migration code, right now there are _two_ > implementations, and savevm/loadvm one gets less love. > > And we will check "much more" the way to load migration in a > non-pristine qemu, so .... > > Later, Juan. This patch just changes a few lines which shuts down the currently running VM and puts the QEMU instance into a state where it can accept an incoming migration. I haven't tested it yet with more complex scenarios, but it appears to work fine so far. I have also started work on a new migration test, which is almost identical to the existing post-copy test, but migrates to a non-pristine QEMU. It works on X86, but not yet on PPC64 because the serial output is different. It needs quite a lot more work, but before I continue, I would like to know first if this is something people fundamentally object to? Richard Palethorpe (2): migrate: Allow incoming migration without defer migrate: Tests for migrating to an already used QEMU migration/migration.c | 12 +++--- tests/migration-test.c | 113 +++++++++++++++++++++++++++++++++++++------------ vl.c | 2 + 3 files changed, 92 insertions(+), 35 deletions(-) -- 2.16.2
