From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53121) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Y1HFA-00055K-ED for qemu-devel@nongnu.org; Wed, 17 Dec 2014 11:14:36 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Y1HF6-0005SO-Db for qemu-devel@nongnu.org; Wed, 17 Dec 2014 11:14:32 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50002) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Y1HF6-0005Rv-5h for qemu-devel@nongnu.org; Wed, 17 Dec 2014 11:14:28 -0500 Date: Wed, 17 Dec 2014 16:14:07 +0000 From: "Dr. David Alan Gilbert" Message-ID: <20141217161406.GB31071@work-vm> References: <1412358473-31398-1-git-send-email-dgilbert@redhat.com> <1412358473-31398-29-git-send-email-dgilbert@redhat.com> <20141104021824.GI27321@voom.fritz.box> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141104021824.GI27321@voom.fritz.box> Subject: Re: [Qemu-devel] [PATCH v4 28/47] qemu_savevm_state_complete: Postcopy changes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: David Gibson Cc: aarcange@redhat.com, yamahata@private.email.ne.jp, quintela@redhat.com, cristian.klein@cs.umu.se, qemu-devel@nongnu.org, amit.shah@redhat.com, yanghy@cn.fujitsu.com * David Gibson (david@gibson.dropbear.id.au) wrote: > On Fri, Oct 03, 2014 at 06:47:34PM +0100, Dr. David Alan Gilbert (git) wrote: > > From: "Dr. David Alan Gilbert" > > > > When postcopy calls qemu_savevm_state_complete it's not really > > the end of migration, so skip: > > a) Finishing postcopiable iterative devices - they'll carry on > > b) The termination byte on the end of the stream. > > > > We then also add: > > qemu_savevm_state_postcopy_complete > > which is called at the end of a postcopy migration to call the > > complete methods on devices skipped in the _complete call. > > So, we should probably rename qemu_savevm_state_complete() to reflect > the fact that it's no longer actually a completion, but just the > transition from pre-copy to post-copy phases. A good, brief name > doesn't immediately occur to me, unfortunately. Well it's still completion in the non-postcopy case; if you do think of a good obvious name then I'd be happy to change it. (Another way would be to add aparameter to qemu_savevm_state_complete to make it do one or the other, but some of the conditions in it were already a bit hairy). > > Signed-off-by: Dr. David Alan Gilbert > > --- > > include/sysemu/sysemu.h | 1 + > > savevm.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++- > > 2 files changed, 52 insertions(+), 1 deletion(-) > > > > diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h > > index e7ff3d0..46665ce 100644 > > --- a/include/sysemu/sysemu.h > > +++ b/include/sysemu/sysemu.h > > @@ -113,6 +113,7 @@ void qemu_savevm_state_cancel(void); > > void qemu_savevm_state_pending(QEMUFile *f, uint64_t max_size, > > uint64_t *res_non_postcopiable, > > uint64_t *res_postcopiable); > > +void qemu_savevm_state_postcopy_complete(QEMUFile *f); > > void qemu_savevm_command_send(QEMUFile *f, enum qemu_vm_cmd command, > > uint16_t len, uint8_t *data); > > void qemu_savevm_send_reqack(QEMUFile *f, uint32_t value); > > diff --git a/savevm.c b/savevm.c > > index a0cb88b..7c4541d 100644 > > --- a/savevm.c > > +++ b/savevm.c > > @@ -854,10 +854,51 @@ int qemu_savevm_state_iterate(QEMUFile *f) > > return ret; > > } > > > > +/* > > + * Calls the complete routines just for those devices that are postcopiable; > > + * causing the last few pages to be sent immediately and doing any associated > > + * cleanup. > > + * Note postcopy also calls the plain qemu_savevm_state_complete to complete > > + * all the other devices, but that happens at the point we switch to postcopy. > > + */ > > +void qemu_savevm_state_postcopy_complete(QEMUFile *f) > > +{ > > + SaveStateEntry *se; > > + int ret; > > + > > + QTAILQ_FOREACH(se, &savevm_handlers, entry) { > > + if (!se->ops || !se->ops->save_live_complete || > > + !se->ops->can_postcopy) { > > So, you check for the presence of a can_postcopy callback, but you > don't ever actually invoke it. Thanks, fixed. > > + continue; > > + } > > + if (se->ops && se->ops->is_active) { > > + if (!se->ops->is_active(se->opaque)) { > > + continue; > > + } > > + } > > + trace_savevm_section_start(se->idstr, se->section_id); > > + /* Section type */ > > + qemu_put_byte(f, QEMU_VM_SECTION_END); > > + qemu_put_be32(f, se->section_id); > > + > > + ret = se->ops->save_live_complete(f, se->opaque); > > I'm wondering if it might be clearer not to overload the > save_live_complete hook, but instead allow both "execution transition" > (old complete) and "final complete" (postcopy complete) hooks > (expecting only one to be non-NULL in most cases). Note that I only call save_live_complete once for any one device. Non-postcopied devices get done in the original loop, postcopied devices in the new ones, so from the point of view of a device it's still a complete. Dave > > -- > David Gibson | I'll have my music baroque, and my code > david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ > | _way_ _around_! > http://www.ozlabs.org/~dgibson -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK