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Re: [Qemu-devel] [PATCH v4 05/32] migration: implement "postcopy-pause"
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH v4 05/32] migration: implement "postcopy-pause" src logic |
Date: |
Fri, 1 Dec 2017 10:49:44 +0000 |
User-agent: |
Mutt/1.9.1 (2017-09-22) |
* Peter Xu (address@hidden) wrote:
> On Thu, Nov 30, 2017 at 10:49:45AM +0000, Dr. David Alan Gilbert wrote:
> > * Peter Xu (address@hidden) wrote:
> > > Now when network down for postcopy, the source side will not fail the
> > > migration. Instead we convert the status into this new paused state, and
> > > we will try to wait for a rescue in the future.
> > >
> > > If a recovery is detected, migration_thread() will reset its local
> > > variables to prepare for that.
> > >
> > > Reviewed-by: Dr. David Alan Gilbert <address@hidden>
> >
> > That's still OK; you might want to consider reusing the 'pause_sem' that I
> > added to MigrationStatus for the other pause case.
>
> Yes I can. I am just a bit worried about how these two different
> features cross-affect each other. Say, what if something tries to
> execute "migrate-continue" during a postcopy network failure? IMHO it
> should not be allowed, but we don't yet have a protection so far.
>
> So I would prefer to still separate these two semaphores.
Yes, that's fair enough; the semantics might be different enough that
they don't quite fit - but worth keeping in mind.
> Though I found that I can move init/destroy of the two new semaphores
> (postcopy_pause_sem, postcopy_pause_rp_sem) into object init/destroy
> just like what we did for pause_sem, which seems to be cleaner. I
> hope I can still keep your r-b if I do that small change. Thanks,
Yes, I think that's OK.
Dave
> --
> Peter Xu
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK