[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] question about migration
On 05/01/16 15:40, Ian Jackson wrote: > Andrew Cooper writes ("Re: [Xen-devel] question about migration"): >> On 04/01/16 17:46, Ian Jackson wrote: >>> Suppose a domain goes into SHUTDOWN with reason code SUSPEND. Then >>> later it is resumed again (perhaps the migration failed). And later >>> it shuts down cleanly. >>> >>> Will this generate a second @releaseDomain ? How is a toolstack >>> supposed to discover this situation ? >> By the looks of it in Xen, domain_resume() sets d->is_shut_down = 0, >> which means a subsequent domain_shutdown() will generate a new VIRQ. >> >> Therefore, a new @releaseDomain will arrive at a later point. > Well, jolly good. > >>> Should libxl simply treat domains in state SHUTDOWN/SUSPEND as if they >>> were running, and not issue a notification to anyone ? >> As far as libxl_evenable_domain_death() is concerned, yes. > Would you like to prepare a patch ? I don't have a repro of the issue. This thread was merely me triaging an issue reported by Wen, given some `git grep`. (There are actually 3 different bugs on different subthreads of this thread.) > >> In general however, no. Consider a libxl user (such as a snapshotting >> utility) which asks a domain to suspend to quiesce the disks and then >> intends to resume the domain. > Currently such a utility would have to use > libxl_evenable_domain_death to discover when the domain suspends, but > that would cause breakage as discussed in this thread. So I think > such a utility would need a new libxl evenable interface. Do you > agree ? This looks like a yakk. Changing the behaviour of libxl_evenable_domain_death() will break the API and also break in-guest users. It also doesn't return the shutdown code, so the caller can't loop while shutdown && suspend. I can't think of a solution which doesn't involve making a brand new function written from scratch. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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