From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50130) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ddY9R-0008O2-51 for qemu-devel@nongnu.org; Fri, 04 Aug 2017 04:40:10 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ddY9O-0001XF-Pt for qemu-devel@nongnu.org; Fri, 04 Aug 2017 04:40:09 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48054) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ddY9O-0001W3-Gl for qemu-devel@nongnu.org; Fri, 04 Aug 2017 04:40:06 -0400 Date: Fri, 4 Aug 2017 16:39:59 +0800 From: Peter Xu Message-ID: <20170804083959.GN5561@pxdev.xzpeter.org> References: <1501229198-30588-1-git-send-email-peterx@redhat.com> <1501229198-30588-28-git-send-email-peterx@redhat.com> <20170803123704.GK2076@work-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20170803123704.GK2076@work-vm> Subject: Re: [Qemu-devel] [RFC 27/29] migration: setup ramstate for resume List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert" Cc: qemu-devel@nongnu.org, Laurent Vivier , Alexey Perevalov , Juan Quintela , Andrea Arcangeli On Thu, Aug 03, 2017 at 01:37:04PM +0100, Dr. David Alan Gilbert wrote: > * Peter Xu (peterx@redhat.com) wrote: > > After we updated the dirty bitmaps of ramblocks, we also need to update > > the critical fields in RAMState to make sure it is ready for a resume. > > > > Signed-off-by: Peter Xu > > --- > > migration/ram.c | 35 ++++++++++++++++++++++++++++++++++- > > 1 file changed, 34 insertions(+), 1 deletion(-) > > > > diff --git a/migration/ram.c b/migration/ram.c > > index c695b13..427bf6e 100644 > > --- a/migration/ram.c > > +++ b/migration/ram.c > > @@ -1947,6 +1947,31 @@ static int ram_state_init(RAMState **rsp) > > return 0; > > } > > > > +static void ram_state_resume_prepare(RAMState *rs) > > +{ > > + RAMBlock *block; > > + long pages = 0; > > + > > + /* > > + * Postcopy is not using xbzrle/compression, so no need for that. > > + * Also, since source are already halted, we don't need to care > > + * about dirty page logging as well. > > + */ > > + > > + RAMBLOCK_FOREACH(block) { > > + pages += bitmap_count_one(block->bmap, > > + block->max_length >> TARGET_PAGE_BITS); > > Again I think that needs to be block->used_length (see > migration_bitmap_sync). Fixing. > > > + } > > + > > + /* This may not be aligned with current bitmaps. Recalculate. */ > > + rs->migration_dirty_pages = pages; > > + > > + rs->last_seen_block = NULL; > > + rs->last_sent_block = NULL; > > + rs->last_page = 0; > > + rs->last_version = ram_list.version; > > A trace at this point with the pages count might be worthwhile. Added. > > > +} > > + > > /* > > * Each of ram_save_setup, ram_save_iterate and ram_save_complete has > > * long-running RCU critical section. When rcu-reclaims in the code > > @@ -2842,8 +2867,16 @@ int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *block) > > static int ram_resume_prepare(MigrationState *s, void *opaque) > > { > > RAMState *rs = *(RAMState **)opaque; > > + int ret; > > > > - return ram_dirty_bitmap_sync_all(s, rs); > > + ret = ram_dirty_bitmap_sync_all(s, rs); > > Interesting; I'd assumed you'd load directly into this > bitmap rather than loading into the bitmap on each block. > Do we ever get the case where a bitmap is set on the source > bitmap but not in the loaded bitmap? (confirmed with Dave offlist that this is not a problem, blame myself on using a poor function name "ram_dirty_bitmap_sync_all" which is too close to existng "migration_bitmap_sync") -- Peter Xu