Re: [Qemu-devel] [PATCH COLO-Frame (Base) v21 03/17] migration: Enter into COLO mode after migration if COLO is enabled

[Amit Shah]

On (Tue) 18 Oct 2016 [20:09:59], zhanghailiang wrote:
> Add a new migration state: MIGRATION_STATUS_COLO. Migration source side
> enters this state after the first live migration successfully finished
> if COLO is enabled by command 'migrate_set_capability x-colo on'.
> 
> We reuse migration thread, so the process of checkpointing will be handled
> in migration thread.
> 
> Signed-off-by: zhanghailiang <address@hidden>
> Signed-off-by: Li Zhijian <address@hidden>
> Signed-off-by: Gonglei <address@hidden>
> Reviewed-by: Dr. David Alan Gilbert <address@hidden>

(snip)

> +static void colo_process_checkpoint(MigrationState *s)
> +{
> +    qemu_mutex_lock_iothread();
> +    vm_start();
> +    qemu_mutex_unlock_iothread();
> +    trace_colo_vm_state_change("stop", "run");
> +
> +    /* TODO: COLO checkpoint savevm loop */
> +
> +    migrate_set_state(&s->state, MIGRATION_STATUS_COLO,
> +                      MIGRATION_STATUS_COMPLETED);

Is this just a temporary thing that'll be removed in the next patches?
I guess so - because once you enter COLO state, you want to remain in
it, right?

I think the commit message implies that.  So the commit msg and the
code are not in sync.

(snip)

> diff --git a/migration/migration.c b/migration/migration.c
> index f7dd9c6..462007d 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -695,6 +695,10 @@ MigrationInfo *qmp_query_migrate(Error **errp)
>  
>          get_xbzrle_cache_stats(info);
>          break;
> +    case MIGRATION_STATUS_COLO:
> +        info->has_status = true;
> +        /* TODO: display COLO specific information (checkpoint info etc.) */
> +        break;

When do you plan to add this?  I guess it's important for debugging
and also to get the state of the system while colo is active.  What
info do you have planned to display here?


                Amit