On Thu, Mar 7, 2019 at 8:37 AM Numan Siddique <nusid...@redhat.com> wrote:
>
>
>
> On Tue, Mar 5, 2019 at 11:34 PM Han Zhou <zhou...@gmail.com> wrote:
>>
>> > > +
>> > > +static void
>> > > +add_to_ha_ref_chassis_info(struct ha_ref_chassis_info *ref_ch_info,
>> > > + const struct sbrec_chassis *chassis)
>> > > +{
>> > > + for (size_t j = 0; j < ref_ch_info->n_ref_chassis; j++) {
>> > > + if (ref_ch_info->ref_chassis[j] == chassis) {
>> > > + return;
>> > > + }
>> > > + }
>> > > +
>> > > + ref_ch_info->ref_chassis = xrealloc(ref_ch_info->ref_chassis,
>> > > + sizeof
>> > > *ref_ch_info->ref_chassis *
>> > > + (++ref_ch_info->n_ref_chassis));
>> >
>> > This may be inefficient, considering the amount of ref chassises to be
>> > added for each HA group. It is better to xrealloc for original_size *
>> > 2 every time and expand only when more space is needed.
>> >
>> > > + ref_ch_info->ref_chassis[ref_ch_info->n_ref_chassis - 1] =
>> > > + CONST_CAST(struct sbrec_chassis *, chassis);
>> > > +}
>> > > +
>> > > +static void
>> > > +update_sb_ha_group_ref_chassis(struct shash *ha_ref_chassis_map)
>> > > +{
>> > > + struct shash_node *node, *next;
>> > > + SHASH_FOR_EACH_SAFE (node, next, ha_ref_chassis_map) {
>> > > + struct ha_ref_chassis_info *ha_ref_info = node->data;
>> > > +
>> > > sbrec_ha_chassis_group_set_ref_chassis(ha_ref_info->ha_chassis_group,
>> > > + ha_ref_info->ref_chassis,
>> > > +
>> > > ha_ref_info->n_ref_chassis);
>> > > + free(ha_ref_info->ref_chassis);
>> > > + free(ha_ref_info);
>> > > + shash_delete(ha_ref_chassis_map, node);
>> > > + }
>> > > +}
>> > > +
>> > > +/* This function returns logical router datapath (with a distributed
>> > > + * gateway port) to which 'od' is connected to - either directly
>> > > + * or indirectly (via transit logical switches).
>> > > + * Returns NULL if no logical router with gw port found.
>> > > + */
>> > > +static struct ovn_datapath *
>> > > +get_router_dp_with_gw_port(struct hmap *ports,
>> > > + struct ovn_datapath *od,
>> > > + struct ovn_datapath *peer_od)
>> > > +{
>> > > + if (!od) {
>> > > + return NULL;
>> > > + }
>> > > +
>> > > + if (od->nbs) {
>> > > + /* It's a logical switch datapath. */
>> > > + if (peer_od) {
>> > > + /* If peer datapath is not logical router, then
>> > > + * something is wrong. */
>> > > + ovs_assert(peer_od->nbr);
>> > > + }
>> > > +
>> > > + for (size_t i = 0; i < od->n_router_ports; i++) {
>> > > + if (!od->router_ports[i]->peer) {
>> > > + /* If there is no peer port connecting to the
>> > > + * router datapath, ignore it. */
>> > > + continue;
>> > > + }
>> > > +
>> > > + struct ovn_datapath *router_dp =
>> > > od->router_ports[i]->peer->od;
>> > > + if (router_dp->l3dgw_port && router_dp->l3dgw_port->nbrp) {
>> > > + /* Router datapath has a distributed gateway router
>> > > port. */
>> > > + return router_dp;
>> >
>> > I think we can't return when just one router_dp is found. There can be
>> > more than one connected router that has gateway router ports. So the
>> > return value of this function should be a set.
>> >
>> > > + }
>> > > + }
>> > > +
>> > > + /* The logical switch datapath is not connected to any
>> > > + * logical router with a distributed gateway port. Check if it
>> > > + * is indirectly connected to a logical router with a gw port.
>> > > */
>> > > + for (size_t i = 0; i < od->n_router_ports; i++) {
>> > > + if (!od->router_ports[i]->peer) {
>> > > + continue;
>> > > + }
>> > > +
>> > > + struct ovn_datapath *router_dp =
>> > > + od->router_ports[i]->peer->od;
>> > > +
>> > > + /* If we don't check this, we will be in an infinite loop.
>> > > */
>> > > + if (router_dp != peer_od) {
>> >
>> > peer_od should also be a set, it should skip checking any datapath
>> > that has already been checked. Consider the case LR1 is connected with
>> > LS1, LS2 and LS3.
>> >
>> > > + router_dp = get_router_dp_with_gw_port(ports, router_dp,
>> > > + od);
>> > > + if (router_dp) {
>> > > + /* Found a logical router with gw port indirectly
>> > > connected
>> > > + * to 'od'. */
>> > > + return router_dp;
>> > > + }
>> > > + }
>> > > + }
>> > > + } else if (od->nbr) {
>> > > + /* It's a logical router datapath. */
>> > > + if (peer_od) {
>> > > + /* If peer datapath is not logical switch, then
>> > > + * something is wrong. */
>> > > + ovs_assert(peer_od->nbs);
>> >
>> > A router port can be peered with another router port directly, so this
>> > assert is not true.
>> >
>> > > + }
>> > > +
>> > > + /* Check if this logical router datapath is indirectly connected
>> > > + * to another logical router via a transit logical switch(es).
>> > > */
>> > > + for (size_t i = 0; i < od->nbr->n_ports; i++) {
>> > > + struct ovn_port *router_port =
>> > > + ovn_port_find(ports, od->nbr->ports[i]->name);
>> > > +
>> > > + if (!router_port || !router_port->peer) {
>> > > + continue;
>> > > + }
>> > > + /* If we don't check this, we will be in an infinite loop.
>> > > */
>> > > + if (router_port->peer->od != peer_od) {
>> > > + struct ovn_datapath *router_dp;
>> > > + /* router_port->peer->od points a logical switch
>> > > datapath. */
>> > > + router_dp = get_router_dp_with_gw_port(ports,
>> > > +
>> > > router_port->peer->od,
>> > > + od);
>> > > + if (router_dp) {
>> > > + /* Found a logical router with gw port indirectly
>> > > connected
>> > > + * to 'od'. */
>> > > + return router_dp;
>> > > + }
>> > > + }
>> > > + }
>> > > + }
>> > > +
>> > > + return NULL;
>> > > +}
>> >
>> > In general, it may refer to the flood-fill approach implemented in
>> > ovn-controller for populating local datapaths in binding.c, which is
>> > similar to the purpose here. However, we should consider an
>> > optimization here since the flood-fill cost would apply for every
>> > port-binding. It can be optimized with a cache, which maps between
>> > each datapath and its related router_dps with gw ports, to avoid
>> > repeated traversing. (In ovn-controller it can be optimized, too, but
>> > the gain is not as big as here since only local port-bindings are
>> > checked in ovn-controller.)
>> >
>
>
> Thanks for the comments Han. I will work on them.
> I haven't thought of an optimization yet. I will try to explore based
> on your suggestions. At the same time, I personally think the code
> shouldn't get complicated because of the optimization. (I feel the present
> code in ovn-controller [1] is a bit complicated -
> [1] - https://github.com/openvswitch/ovs/blob/master/ovn/controller/bfd.c#L98
> )
Sorry, I should point out the location more clearly. I was talking
about this code:
https://github.com/openvswitch/ovs/blob/master/ovn/controller/binding.c#L113
It is about the algorithm that calculates related datapaths. I think
we need similar logic in northd, but since northd handles all port
bindings, it is worth to optimize with a cache to avoid repeat this
calculation for every port-binding.
>
> I think it is uncommon to have indirect logical router connections which
> eventually
> connect to a router with a gateway router port.
> May be I am wrong. Do you think it's common to have such setups ?
>
It may be uncommon, but I think it is important to make it correct in
these situations.
>
>> I forgot to mention, this implementation is for finding out the
>> required BFD sessions, however, it can be reused for a more generic
>> purpose - to figure out whether a tunnel is needed between each pair
>> of chassises. There happens to be a related discussion ongoing here:
>> https://mail.openvswitch.org/pipermail/ovs-discuss/2019-March/048281.html
>>
>
> I have seen thread. I will try to make it generic.
> If not I think we can revisit the code later and make it generic and more
> optimized.
> As a first step I think it should be reasonable to aim to have the solution
> for the HA_Chassis_Group's ref_chassis calculation.
> Does this sound good ?
>
I think it is fair to have separate patches to address the
optimizations. For current patch, if it is only about making HA group
generic for both GW and external port, I think we can simply put all
chassises as ref_chassis for all GW HA-groups, and enable bfd for
them, to make it work just like how it behaves today. Further
optimizations can be added separately.
Thanks,
Han
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