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Re: [Qemu-devel] [PATCH v6 21/28] migration: setup ramstate for resume
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH v6 21/28] migration: setup ramstate for resume |
Date: |
Wed, 14 Feb 2018 18:40:46 +0000 |
User-agent: |
Mutt/1.9.2 (2017-12-15) |
* 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.
Dave
> Thanks,
>
> --
> Peter Xu
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- [Qemu-devel] [PATCH v6 14/28] migration: wakeup dst ram-load-thread for recover, (continued)
- [Qemu-devel] [PATCH v6 14/28] migration: wakeup dst ram-load-thread for recover, Peter Xu, 2018/02/08
- [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