Re: [Qemu-devel] [PATCH v7 23/42] MIGRATION_STATUS_POSTCOPY_ACTIVE: Add new migration state

[Juan Quintela]

"Dr. David Alan Gilbert (git)" <address@hidden> wrote:
> From: "Dr. David Alan Gilbert" <address@hidden>
>
> 'MIGRATION_STATUS_POSTCOPY_ACTIVE' is entered after migrate_start_postcopy
>
> 'migration_postcopy_phase' is provided for other sections to know if
> they're in postcopy.
>
> Signed-off-by: Dr. David Alan Gilbert <address@hidden>
> Reviewed-by: David Gibson <address@hidden>
> Reviewed-by: Eric Blake <address@hidden>

Reviewed-by: Juan Quintela <address@hidden>


But (there is always a but....)


> @@ -358,6 +359,39 @@ MigrationInfo *qmp_query_migrate(Error **errp)
>  
>          get_xbzrle_cache_stats(info);
>          break;
> +    case MIGRATION_STATUS_POSTCOPY_ACTIVE:
> +        /* Mostly the same as active; TODO add some postcopy stats */
> +        info->has_status = true;
> +        info->has_total_time = true;
> +        info->total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME)
> +            - s->total_time;
> +        info->has_expected_downtime = true;
> +        info->expected_downtime = s->expected_downtime;
> +        info->has_setup_time = true;
> +        info->setup_time = s->setup_time;
> +
> +        info->has_ram = true;
> +        info->ram = g_malloc0(sizeof(*info->ram));
> +        info->ram->transferred = ram_bytes_transferred();
> +        info->ram->remaining = ram_bytes_remaining();
> +        info->ram->total = ram_bytes_total();
> +        info->ram->duplicate = dup_mig_pages_transferred();
> +        info->ram->skipped = skipped_mig_pages_transferred();
> +        info->ram->normal = norm_mig_pages_transferred();
> +        info->ram->normal_bytes = norm_mig_bytes_transferred();
> +        info->ram->dirty_pages_rate = s->dirty_pages_rate;
> +        info->ram->mbps = s->mbps;
> +
> +        if (blk_mig_active()) {
> +            info->has_disk = true;
> +            info->disk = g_malloc0(sizeof(*info->disk));
> +            info->disk->transferred = blk_mig_bytes_transferred();
> +            info->disk->remaining = blk_mig_bytes_remaining();
> +            info->disk->total = blk_mig_bytes_total();
> +        }

Can we have block migration active with postcopy?  I would assume that
this would get disk corruption, no?  Or if you preffer the other
question, what protects us from disk corruption?

Once here, I guess we can get the migrate_already_active() bit without
problem?

Later, Juan.