Re: [PATCH 3/5] migration: remove multifd check with postcopy

[Peter Xu <peterx@redhat.com>]

On Mon, Nov 04, 2024 at 05:53:22PM +0530, Prasad Pandit wrote:
> On Fri, 1 Nov 2024 at 20:06, Peter Xu <peterx@redhat.com> wrote:
> > > -    return s->capabilities[MIGRATION_CAPABILITY_MULTIFD];
> > > +    return s->capabilities[MIGRATION_CAPABILITY_MULTIFD]
> > > +            && !migration_in_postcopy();
> > >  }
> >
> > We need to keep this as-is.. I'm afraid.
> > You can always do proper check with multifd & !postcopy in your use cases.
> 
> * Above change simplifies it a lot. Separate checks as
> migrate_multifd() && !migration_in_postcopy() make it more complicated
> to follow, because migrate_multifd() is often combined with other
> checks like migrate_multifd_flush, or migrate_mapped_ram etc. I was
> hoping to avoid adding one more check to those conditionals. Also,
> with the above change we don't have to explicitly check where to add
> !migration_in_postcopy() check.

We definitely need a helper like this to simply detect what the user chose
on the feature.

You can still introduce a new helper, e.g. migrate_multifd_precopy(), if
that simplifies the code.

Thanks,

> 
> * Will try to separate them.
> 
> Thank you.
> ---
>   - Prasad
> 

-- 
Peter Xu