Re: [PATCH v2 24/29] migration/ram: Ignore multifd flush when doing fixed-ram migration

[Daniel P . Berrangé]

On Mon, Oct 23, 2023 at 05:36:03PM -0300, Fabiano Rosas wrote:
> Some functionalities of multifd are incompatible with the 'fixed-ram'
> migration format.
> 
> The MULTIFD_FLUSH flag in particular is not used because in fixed-ram
> there is no sinchronicity between migration source and destination so
> there is not need for a sync packet. In fact, fixed-ram disables
> packets in multifd as a whole.
> 
> Make sure RAM_SAVE_FLAG_MULTIFD_FLUSH is never emitted when fixed-ram
> is enabled.
> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>
> ---
>  migration/ram.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/migration/ram.c b/migration/ram.c
> index 8e34c1b597..3497ed186a 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -1386,7 +1386,7 @@ static int find_dirty_block(RAMState *rs, 
> PageSearchStatus *pss)
>          pss->page = 0;
>          pss->block = QLIST_NEXT_RCU(pss->block, next);
>          if (!pss->block) {
> -            if (migrate_multifd() &&
> +            if (!migrate_fixed_ram() && migrate_multifd() &&

If I'm nitpicking I would put migrate_multifd() first in the
conditional, because fixed-ram is a sub-feature of multifd.

Either way though

  Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>


>                  !migrate_multifd_flush_after_each_section()) {
>                  QEMUFile *f = rs->pss[RAM_CHANNEL_PRECOPY].pss_channel;
>                  int ret = multifd_send_sync_main(f);
> -- 
> 2.35.3
> 

With regards,
Daniel
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