Re: [Qemu-devel] [PATCH v7 20/42] Modify save_live_pending for postcopy

[Juan Quintela]

"Dr. David Alan Gilbert (git)" <address@hidden> wrote:
> From: "Dr. David Alan Gilbert" <address@hidden>
>
> Modify save_live_pending to return separate postcopiable and
> non-postcopiable counts.
>
> Signed-off-by: Dr. David Alan Gilbert <address@hidden>

Reviewed-by: Juan Quintela <address@hidden>

I think that if you make a small change of meaning, everything gots easier:

> -static uint64_t block_save_pending(QEMUFile *f, void *opaque, uint64_t 
> max_size)
> +static void block_save_pending(QEMUFile *f, void *opaque, uint64_t max_size,
> +                               uint64_t *non_postcopiable_pending,
> +                               uint64_t *postcopiable_pending)
>  {
>      /* Estimate pending number of bytes to send */
>      uint64_t pending;
> @@ -773,7 +775,8 @@ static uint64_t block_save_pending(QEMUFile *f, void 
> *opaque, uint64_t max_size)
>      qemu_mutex_unlock_iothread();
>  
>      DPRINTF("Enter save live pending  %" PRIu64 "\n", pending);
> -    return pending;
> +    *non_postcopiable_pending = pending;
> +    *postcopiable_pending = 0;

Change that two lines to:

       *non_postcopiable_pending += pending;
       *postcopiable_pending += 0; /* ok, equivalent of doing nothing */

This way, chaining gots easier?




> diff --git a/migration/savevm.c b/migration/savevm.c
> index 2c4cbe1..ebd3d31 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -1012,10 +1012,20 @@ void qemu_savevm_state_complete_precopy(QEMUFile *f)
>      qemu_fflush(f);
>  }
>  
> -uint64_t qemu_savevm_state_pending(QEMUFile *f, uint64_t max_size)
> +/* Give an estimate of the amount left to be transferred,
> + * the result is split into the amount for units that can and
> + * for units that can't do postcopy.
> + */
> +void qemu_savevm_state_pending(QEMUFile *f, uint64_t max_size,
> +                               uint64_t *res_non_postcopiable,
> +                               uint64_t *res_postcopiable)
>  {
>      SaveStateEntry *se;
> -    uint64_t ret = 0;
> +    uint64_t tmp_non_postcopiable, tmp_postcopiable;
> +
> +    *res_non_postcopiable = 0;
> +    *res_postcopiable = 0;
> +
>  
>      QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
>          if (!se->ops || !se->ops->save_live_pending) {
> @@ -1026,9 +1036,12 @@ uint64_t qemu_savevm_state_pending(QEMUFile *f, 
> uint64_t max_size)
>                  continue;
>              }
>          }
> -        ret += se->ops->save_live_pending(f, se->opaque, max_size);
> +        se->ops->save_live_pending(f, se->opaque, max_size,
> +                                   &tmp_non_postcopiable, &tmp_postcopiable);
> +
> +        *res_postcopiable += tmp_postcopiable;
> +        *res_non_postcopiable += tmp_non_postcopiable;
>      }
> -    return ret;

With the change, we don't care in the other functions, and this one gets
simpler IMHO.