From: Paolo Bonzini <pbonzini@redhat.com>
To: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: "quintela@redhat.com" <quintela@redhat.com>,
"libvir-list@redhat.com" <libvir-list@redhat.com>,
Yanqiangjun <yanqiangjun@huawei.com>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
"Zhaoyanbin (A)" <lefty.zhao@huawei.com>,
Zengjunliang <zengjunliang@huawei.com>,
"Gonglei (Arei)" <arei.gonglei@huawei.com>
Subject: Re: [Qemu-devel] [PATCH] migration: Fix possible bug for migrate cancel
Date: Fri, 28 Mar 2014 13:16:16 +0100 [thread overview]
Message-ID: <53356810.8020206@redhat.com> (raw)
In-Reply-To: <20140328113001.GB2450@work-vm>
Il 28/03/2014 12:30, Dr. David Alan Gilbert ha scritto:
>> > Another reason for doing it in libvirt is that the serialization
>> > between cancellation and completion of migration ultimately is
>> > controlled by libvirt's lock. Doing this in QEMU makes it harder to
>> > reason about concurrency.
> I think you have to be careful when you talk about 'cancellation and completion
> of migration' - in that paragraph I don't think you mean the same thing
> as MIG_STATE_CANCELLED and MIG_STATE_COMPLETED, I think you're talking
> about the larger scale idea of completion after you take into account
> that the VM might be paused after qemu has gone to MIG_STATE_COMPLETED and
> libvirt might still decide it wants to give up and use the version on
> the source that's still paused.
Yes, exactly. This is why I considered the possibility of adding a
"cancelled" flag within libvirt.
Libvirt always uses -S on the destination, so it's always possible to
cancel migration even after MIG_STATE_COMPLETED.
Paolo
prev parent reply other threads:[~2014-03-28 12:16 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-24 13:04 [Qemu-devel] [PATCH] migration: Fix possible bug for migrate cancel arei.gonglei
2014-03-24 14:14 ` Eric Blake
2014-03-24 15:47 ` Paolo Bonzini
2014-03-24 16:00 ` Eric Blake
2014-03-25 11:15 ` Gonglei (Arei)
2014-03-28 9:18 ` Gonglei (Arei)
2014-03-28 9:28 ` Paolo Bonzini
2014-03-28 11:30 ` Dr. David Alan Gilbert
2014-03-28 12:16 ` Paolo Bonzini [this message]
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