max-bandwidth is set by default to 32 MiB/s (256 Mib/s)
since 2008 (5bb7910a).

Most of the CPUs can dirty memory faster than that now,
and this is clearly a problem with POWER where the page
size is 64 kiB and not 4 KiB.

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Message-Id: <20200921144957.979989-1-lvivier@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>