From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33919) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZEguJ-0005hC-8u for qemu-devel@nongnu.org; Mon, 13 Jul 2015 12:48:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZEguE-0004ij-OM for qemu-devel@nongnu.org; Mon, 13 Jul 2015 12:48:43 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53045) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZEguE-0004iX-Gj for qemu-devel@nongnu.org; Mon, 13 Jul 2015 12:48:38 -0400 Date: Mon, 13 Jul 2015 17:48:31 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20150713164831.GJ2492@work-vm> References: <1434450415-11339-1-git-send-email-dgilbert@redhat.com> <1434450415-11339-24-git-send-email-dgilbert@redhat.com> <87y4ikjo1n.fsf@neno.neno> <20150713155310.GH2492@work-vm> <87vbdohvmo.fsf@neno.neno> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87vbdohvmo.fsf@neno.neno> Subject: Re: [Qemu-devel] [PATCH v7 23/42] MIGRATION_STATUS_POSTCOPY_ACTIVE: Add new migration state List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Juan Quintela Cc: aarcange@redhat.com, yamahata@private.email.ne.jp, liang.z.li@intel.com, qemu-devel@nongnu.org, luis@cs.umu.se, amit.shah@redhat.com, pbonzini@redhat.com, david@gibson.dropbear.id.au * Juan Quintela (quintela@redhat.com) wrote: > "Dr. David Alan Gilbert" wrote: > > * Juan Quintela (quintela@redhat.com) wrote: > >> "Dr. David Alan Gilbert (git)" wrote: > >> > From: "Dr. David Alan Gilbert" > >> > > >> > 'MIGRATION_STATUS_POSTCOPY_ACTIVE' is entered after migrate_start_postcopy > >> > > >> > 'migration_postcopy_phase' is provided for other sections to know if > >> > they're in postcopy. > >> > > >> > Signed-off-by: Dr. David Alan Gilbert > >> > Reviewed-by: David Gibson > >> > Reviewed-by: Eric Blake > >> > >> Reviewed-by: Juan Quintela > >> > >> > >> But (there is always a but....) > >> > >> > >> > @@ -358,6 +359,39 @@ MigrationInfo *qmp_query_migrate(Error **errp) > >> > > >> > get_xbzrle_cache_stats(info); > >> > break; > >> > + case MIGRATION_STATUS_POSTCOPY_ACTIVE: > >> > + /* Mostly the same as active; TODO add some postcopy stats */ > >> > + info->has_status = true; > >> > + info->has_total_time = true; > >> > + info->total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME) > >> > + - s->total_time; > >> > + info->has_expected_downtime = true; > >> > + info->expected_downtime = s->expected_downtime; > >> > + info->has_setup_time = true; > >> > + info->setup_time = s->setup_time; > >> > + > >> > + info->has_ram = true; > >> > + info->ram = g_malloc0(sizeof(*info->ram)); > >> > + info->ram->transferred = ram_bytes_transferred(); > >> > + info->ram->remaining = ram_bytes_remaining(); > >> > + info->ram->total = ram_bytes_total(); > >> > + info->ram->duplicate = dup_mig_pages_transferred(); > >> > + info->ram->skipped = skipped_mig_pages_transferred(); > >> > + info->ram->normal = norm_mig_pages_transferred(); > >> > + info->ram->normal_bytes = norm_mig_bytes_transferred(); > >> > + info->ram->dirty_pages_rate = s->dirty_pages_rate; > >> > + info->ram->mbps = s->mbps; > >> > + > >> > + if (blk_mig_active()) { > >> > + info->has_disk = true; > >> > + info->disk = g_malloc0(sizeof(*info->disk)); > >> > + info->disk->transferred = blk_mig_bytes_transferred(); > >> > + info->disk->remaining = blk_mig_bytes_remaining(); > >> > + info->disk->total = blk_mig_bytes_total(); > >> > + } > >> > >> Can we have block migration active with postcopy? I would assume that > >> this would get disk corruption, no? Or if you preffer the other > >> question, what protects us from disk corruption? > > > > I think you can, I've not tried it; however I also think it should > > be safe. > > > > migration/block.c's block_save_pending always puts a value in the > > non_postcopiable_pending return value (and 0 in the postcopiable_pending); > > the migrate thread checks the non_postcopiable_pending size to > > decide when it can switch to postcopy, and performs a call to the complete > > method on each device before it does. Thus the block migration should > > be finished before we start doing the actual postcopy stage, and thus > > before the destination CPU starts running. > > I mean that as it is right now, the info under blk_mig_active() check > would be zero/the same than before entering postcopy. Ah, yes; would blk_mig_bytes_total/transferred still have valid values you would want to display, even at the end of the block migration phase? > > > > A possibly harder question is what happens if block.c did implement > > postcopy and you had both block postcopy and ram postcopy active at > > the same time; again I think it should work but I'm not sure if one > > would starve the other. > > > >> Once here, I guess we can get the migrate_already_active() bit without > >> problem? > > > > I'm not sure of the question here; but the idea of migration_already_active() > > is just to avoid all of the open-coded checks for each possible state; > > now we've added anothe state they were getting messy. > > Sorry. I mean that the migrate_already_active() bits can get in without > further ado. Don't need to wait for postcopy to be integrated. Yes; do you want it split out? Dave > > > > > Dave > > > >> > >> Later, Juan. > > -- > > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK