Re: [PATCH v3 04/17] migration: Simplify migration_iteration_run()

[Vladimir Sementsov-Ogievskiy]

On 11/3/22 19:16, Avihai Horon wrote:
> From: Juan Quintela <quintela@redhat.com>
>
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> Signed-off-by: Avihai Horon <avihaih@nvidia.com>
> ---
>   migration/migration.c | 25 +++++++++++++------------
>   1 file changed, 13 insertions(+), 12 deletions(-)
>
> diff --git a/migration/migration.c b/migration/migration.c
> index ffe868b86f..59cc3c309b 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -3743,23 +3743,24 @@ static MigIterateState 
> migration_iteration_run(MigrationState *s)
>   
>       trace_migrate_pending(pending_size, s->threshold_size, pend_pre, pend_post);
>   
> -    if (pending_size && pending_size >= s->threshold_size) {
> -        /* Still a significant amount to transfer */
> -        if (!in_postcopy && pend_pre <= s->threshold_size &&
> -            qatomic_read(&s->start_postcopy)) {
> -            if (postcopy_start(s)) {
> -                error_report("%s: postcopy failed to start", __func__);
> -            }
> -            return MIG_ITERATE_SKIP;
> -        }
> -        /* Just another iteration step */
> -        qemu_savevm_state_iterate(s->to_dst_file, in_postcopy);
> -    } else {
> +
> +    if (pending_size < s->threshold_size) {

Is corner case "pending_size == s->threshold_size == 0" theoretically possible 
here? In this case prepatch we go to completion. Afterpatch we go to next iteration..

>           trace_migration_thread_low_pending(pending_size);
>           migration_completion(s);
>           return MIG_ITERATE_BREAK;
>       }
>   
> +    /* Still a significant amount to transfer */
> +    if (!in_postcopy && pend_pre <= s->threshold_size &&
> +        qatomic_read(&s->start_postcopy)) {
> +        if (postcopy_start(s)) {
> +            error_report("%s: postcopy failed to start", __func__);
> +        }
> +        return MIG_ITERATE_SKIP;
> +    }
> +
> +    /* Just another iteration step */
> +    qemu_savevm_state_iterate(s->to_dst_file, in_postcopy);
>       return MIG_ITERATE_RESUME;
>   }
>   

--
Best regards,
Vladimir