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Re: [Qemu-devel] [PATCH v6 21/28] migration: setup ramstate for resume
From: |
Peter Xu |
Subject: |
Re: [Qemu-devel] [PATCH v6 21/28] migration: setup ramstate for resume |
Date: |
Thu, 22 Feb 2018 15:34:00 +0800 |
User-agent: |
Mutt/1.9.1 (2017-09-22) |
On Wed, Feb 14, 2018 at 06:40:46PM +0000, Dr. David Alan Gilbert wrote:
> * Peter Xu (address@hidden) wrote:
> > On Tue, Feb 13, 2018 at 06:17:51PM +0000, Dr. David Alan Gilbert wrote:
> > > * Peter Xu (address@hidden) 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 <address@hidden>
> > > > ---
> > > > migration/ram.c | 40 +++++++++++++++++++++++++++++++++++++++-
> > > > migration/trace-events | 1 +
> > > > 2 files changed, 40 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/migration/ram.c b/migration/ram.c
> > > > index a2a4b05d5c..d275875f54 100644
> > > > --- a/migration/ram.c
> > > > +++ b/migration/ram.c
> > > > @@ -2250,6 +2250,36 @@ static int ram_init_all(RAMState **rsp)
> > > > return 0;
> > > > }
> > > >
> > > > +static void ram_state_resume_prepare(RAMState *rs, QEMUFile *out)
> > > > +{
> > > > + 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->used_length >>
> > > > TARGET_PAGE_BITS);
> > > > + }
> > > > +
> > > > + /* This may not be aligned with current bitmaps. Recalculate. */
> > > > + rs->migration_dirty_pages = pages;
> > >
> > > migration_dirty_pages is uint64_t - so we should probably do the cast
> > > above and keep 'pages' as uint64_t.
> >
> > Sure.
> >
> > >
> > > > + rs->last_seen_block = NULL;
> > > > + rs->last_sent_block = NULL;
> > > > + rs->last_page = 0;
> > > > + rs->last_version = ram_list.version;
> > >
> > > Do you need to explicitly set
> > > rs->ram_bulk_stage = false;
> > >
> > > if the failure happened just after the start of postcopy and no
> > > requested pages had been sent, I think it might still be set?
> >
> > Could you elaborate what would go wrong even if it's still set?
>
> I think it might start sending all pages rather than just those
> that are dirty/needed; see migration_bitmap_find_dirty.
Ah yes. I should turn it off.
--
Peter Xu
- [Qemu-devel] [PATCH v6 15/28] migration: new cmd MIG_CMD_RECV_BITMAP, (continued)
- [Qemu-devel] [PATCH v6 15/28] migration: new cmd MIG_CMD_RECV_BITMAP, Peter Xu, 2018/02/08
- [Qemu-devel] [PATCH v6 16/28] migration: new message MIG_RP_MSG_RECV_BITMAP, Peter Xu, 2018/02/08
- [Qemu-devel] [PATCH v6 17/28] migration: new cmd MIG_CMD_POSTCOPY_RESUME, Peter Xu, 2018/02/08
- [Qemu-devel] [PATCH v6 18/28] migration: new message MIG_RP_MSG_RESUME_ACK, Peter Xu, 2018/02/08
- [Qemu-devel] [PATCH v6 19/28] migration: introduce SaveVMHandlers.resume_prepare, Peter Xu, 2018/02/08
- [Qemu-devel] [PATCH v6 20/28] migration: synchronize dirty bitmap for resume, Peter Xu, 2018/02/08
- [Qemu-devel] [PATCH v6 21/28] migration: setup ramstate for resume, Peter Xu, 2018/02/08
[Qemu-devel] [PATCH v6 23/28] migration: init dst in migration_object_init too, Peter Xu, 2018/02/08
[Qemu-devel] [PATCH v6 22/28] migration: final handshake for the resume, Peter Xu, 2018/02/08
[Qemu-devel] [PATCH v6 25/28] qmp/migration: new command migrate-recover, Peter Xu, 2018/02/08
[Qemu-devel] [PATCH v6 24/28] io: let watcher of the channel run in same ctx, Peter Xu, 2018/02/08
[Qemu-devel] [PATCH v6 26/28] hmp/migration: add migrate_recover command, Peter Xu, 2018/02/08
[Qemu-devel] [PATCH v6 27/28] migration/qmp: add command migrate-pause, Peter Xu, 2018/02/08