From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59076) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZEzSC-00055z-71 for qemu-devel@nongnu.org; Tue, 14 Jul 2015 08:36:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZEzS8-00087k-Mr for qemu-devel@nongnu.org; Tue, 14 Jul 2015 08:36:56 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52164) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZEzS8-00087e-Ho for qemu-devel@nongnu.org; Tue, 14 Jul 2015 08:36:52 -0400 From: Juan Quintela In-Reply-To: <1434450415-11339-36-git-send-email-dgilbert@redhat.com> (David Alan Gilbert's message of "Tue, 16 Jun 2015 11:26:48 +0100") References: <1434450415-11339-1-git-send-email-dgilbert@redhat.com> <1434450415-11339-36-git-send-email-dgilbert@redhat.com> Date: Tue, 14 Jul 2015 14:36:50 +0200 Message-ID: <87twt6gbkt.fsf@neno.neno> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] [PATCH v7 35/42] Don't sync dirty bitmaps in postcopy Reply-To: quintela@redhat.com List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert (git)" 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 "Dr. David Alan Gilbert (git)" wrote: > From: "Dr. David Alan Gilbert" > > Once we're in postcopy the source processors are stopped and memory > shouldn't change any more, so there's no need to look at the dirty > map. > > There are two notes to this: > 1) If we do resync and a page had changed then the page would get > sent again, which the destination wouldn't allow (since it might > have also modified the page) > 2) Before disabling this I'd seen very rare cases where a page had been > marked dirtied although the memory contents are apparently identical > > Signed-off-by: Dr. David Alan Gilbert > Reviewed-by: David Gibson Reviewed-by: Juan Quintela But, in what patch do we sync the migratioon bitmap after changing to postcopy? > --- > migration/ram.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/migration/ram.c b/migration/ram.c > index 01a0ab4..5cff4d6 100644 > --- a/migration/ram.c > +++ b/migration/ram.c > @@ -1643,7 +1643,9 @@ static int ram_save_complete(QEMUFile *f, void *opaque) > { > rcu_read_lock(); > > - migration_bitmap_sync(); > + if (!migration_postcopy_phase(migrate_get_current())) { > + migration_bitmap_sync(); > + } > > ram_control_before_iterate(f, RAM_CONTROL_FINISH); > > @@ -1678,7 +1680,8 @@ static void ram_save_pending(QEMUFile *f, void *opaque, uint64_t max_size, > > remaining_size = ram_save_remaining() * TARGET_PAGE_SIZE; > > - if (remaining_size < max_size) { > + if (!migration_postcopy_phase(migrate_get_current()) && > + remaining_size < max_size) { > qemu_mutex_lock_iothread(); > rcu_read_lock(); > migration_bitmap_sync();