Re: [Qemu-devel] [PATCH v7 17/23] migration: setup ramstate for resume

[Peter Xu]

On Mon, Mar 12, 2018 at 05:30:12PM +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        | 45 ++++++++++++++++++++++++++++++++++++++++++++-
> >  migration/trace-events |  1 +
> >  2 files changed, 45 insertions(+), 1 deletion(-)
> > 
> > diff --git a/migration/ram.c b/migration/ram.c
> > index 196b1ba876..5cd9f43728 100644
> > --- a/migration/ram.c
> > +++ b/migration/ram.c
> > @@ -2254,6 +2254,41 @@ static int ram_init_all(RAMState **rsp)
> >      return 0;
> >  }
> >  
> > +static void ram_state_resume_prepare(RAMState *rs, QEMUFile *out)
> > +{
> > +    RAMBlock *block;
> > +    uint64_t 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;
> > +
> > +    rs->last_seen_block = NULL;
> > +    rs->last_sent_block = NULL;
> > +    rs->last_page = 0;
> > +    rs->last_version = ram_list.version;
> > +    /*
> > +     * Disable the bulk stage, otherwise we'll resend the whole RAM no
> > +     * matter what we have sent.
> > +     */
> > +    rs->ram_bulk_stage = false;
> > +
> > +    /* Update RAMState cache of output QEMUFile */
> > +    rs->f = out;
> > +
> > +    trace_ram_state_resume_prepare(pages);
> > +}
> > +
> >  /*
> >   * Each of ram_save_setup, ram_save_iterate and ram_save_complete has
> >   * long-running RCU critical section.  When rcu-reclaims in the code
> > @@ -3182,8 +3217,16 @@ out:
> >  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);
> > +    if (ret) {
> > +        return ret;
> > +    }
> > +
> > +    ram_state_resume_prepare(rs, s->to_dst_file);
> > +
> > +    return 0;
> >  }
> >  
> >  static SaveVMHandlers savevm_ram_handlers = {
> > diff --git a/migration/trace-events b/migration/trace-events
> > index 45b1d89217..f5913ff51c 100644
> > --- a/migration/trace-events
> > +++ b/migration/trace-events
> > @@ -88,6 +88,7 @@ ram_dirty_bitmap_reload_complete(char *str) "%s"
> >  ram_dirty_bitmap_sync_start(void) ""
> >  ram_dirty_bitmap_sync_wait(void) ""
> >  ram_dirty_bitmap_sync_complete(void) ""
> > +ram_state_resume_prepare(long v) "%ld"
> 
> Actually, just noticed that's a long but the values passed is now
> uint64_t - be careful.

Yeah, will fix that up.  Thanks,

-- 
Peter Xu