Re: [PATCH v3 23/23] migration: Use multifd before we check for the zero page

[Dr. David Alan Gilbert]

* Juan Quintela (quintela@redhat.com) wrote:
> "Dr. David Alan Gilbert" <dgilbert@redhat.com> wrote:
> > * Juan Quintela (quintela@redhat.com) wrote:
> >> So we use multifd to transmit zero pages.
> >> 
> >> Signed-off-by: Juan Quintela <quintela@redhat.com>
> >> ---
> >>  migration/ram.c | 22 +++++++++++-----------
> >>  1 file changed, 11 insertions(+), 11 deletions(-)
> >> 
> >> diff --git a/migration/ram.c b/migration/ram.c
> >> index 57efa67f20..3ae094f653 100644
> >> --- a/migration/ram.c
> >> +++ b/migration/ram.c
> >> @@ -2138,6 +2138,17 @@ static int ram_save_target_page(RAMState *rs, 
> >> PageSearchStatus *pss,
> >>      ram_addr_t offset = ((ram_addr_t)pss->page) << TARGET_PAGE_BITS;
> >>      int res;
> >>  
> >> +    /*
> >> +     * Do not use multifd for:
> >> +     * 1. Compression as the first page in the new block should be posted 
> >> out
> >> +     *    before sending the compressed page
> >> +     * 2. In postcopy as one whole host page should be placed
> >> +     */
> >> +    if (!save_page_use_compression(rs) && migrate_use_multifd()
> >> +        && !migration_in_postcopy()) {
> >> +        return ram_save_multifd_page(rs, block, offset);
> >> +    }
> >> +
> >>      if (control_save_page(rs, block, offset, &res)) {
> >>          return res;
> >>      }
> >
> > Although I don't think it currently matters, I think that should be
> > after the control_save_page.
> 
> This needs to be improved to be compatible with old versions.
> 
> But .... if we don't care about RDMA, why do we care about
> control_save_page()?

That's why I said I don't think it currently matters; but the patch
seemed a little odd since it changed this order which isn't what
it said.

Dave

> Later, Juan.
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK