On Thu, Sep 25, 2025 at 1:21 PM Mark Michelson <mmich...@redhat.com> wrote:
>
> On Thu, Sep 25, 2025 at 1:13 PM Mark Michelson <mmich...@redhat.com> wrote:
> >
> > I can see the reasoning behind the current code. If the port is
> > definitely not associated with a router at all, then don't bother
> > trying to look in lr_ports for it. It saves a lookup into lr_ports.
> > However, I wonder in practice how much computation this actually
> > saves. get_lport_type() is an if-else ladder that performs strcmp()
> > operations. ovn_port_find() does a hashed lookup of the port and a
> > strcmp() to verify that the hashed port is the one we want. If the
> > port does not exist in lr_ports at all, there is a decent chance that
> > HMAP_FOR_EACH_WITH_HASH () will calculate the hash, provide no
> > matches, and end the loop after zero iterations.
> >
> > Without having measured this at all (IMPORTANT!!), I would reason that
> > doing two ovn_port_find() operations in lr_ports and then ls_ports
> > might be cheaper than calling get_lport_type() and then calling
> > ovn_port_find() in ls_ports. And it certainly is cheaper than calling
> > get_lport_type(), and then calling ovn_port_find() two times.
> >
> > If we really need to measure this, then we can, but I currently am in
> > support of the change proposed by Ales. There is a chance this
> > actually improves performance compared to the current code, and it
> > eliminates a function whose name can be misleading.
>
> And one final note: If the goal is simply to tell if a port_binding is
> associated with a switch or router, then keep in mind that in 25.09+,
> the datapath_binding table has a "type" field on it. An alternate idea
> would be to redefine is_pb_router_type() in the following way:
>
> bool
> is_pb_router_type(const struct port_binding *pb)
> {
> if (!pb->datapath) {
> return false;
> }
> if (!strcmp(pb->datapath->type, "logical-router")) {
> return true;
> }
> return false;
> }
And of course immediately after I sent this I realized this can be a one-liner:
return pb->datapath && !stcmp(pb->datapath->type, "logical_router");
>
> Then you have a relatively cheap function that can take a port binding
> and determine for certain whether it is associated with a logical
> router. This would allow for us to always perform a single strcmp()
> and a single ovn_port_find() call.
>
> >
> > On Thu, Sep 25, 2025 at 10:48 AM Numan Siddique <num...@ovn.org> wrote:
> > >
> > > On Thu, Sep 25, 2025 at 8:21 AM Ales Musil via dev
> > > <ovs-dev@openvswitch.org> wrote:
> > > >
> > > > That function is misleading as the type isn't guaranteed to be
> > > > always LRP. The only place where this function was used knew about
> > > > this hidden logic and did a lookup the lookup twice anyway. Let's
> > > > skip this micro optimization whatsoever and do the lookup twice
> > > > when needed.
> > > >
> > > > Signed-off-by: Ales Musil <amu...@redhat.com>
> > >
> > > I agree with the function name not being very intuitive. When I added
> > > this function, I meant a port binding
> > > which is of type router. If you see, we have a logical switch port of
> > > type "router". This function doesn't
> > > say if the corresponding logical port of the "port_binding" in the NB
> > > DB is a _logical_router_port_ or not, but it indicates
> > > if it is a router port (which can belong to a logical switch or router).
> > >
> > > With this patch, whenever a port binding (irrespective of type) gets
> > > updated we will lookup the lr_map first and then ls_map
> > > and we are introducing an extra cost of look up. Which is not the
> > > case without this patch. For VIF port bindings we will only lookup in
> > > the ls_map.
> > >
> > > If we don't want to use this function, my suggestion would be for
> > > northd to write "datapath=router" or "datapath=switch" in the
> > > external_ids of port bindings.
> > > This way we can do a lookup in the proper map when handling port
> > > binding changes.
> > >
> > > Thanks
> > > Numan
> > >
> > >
> > > > ---
> > > > lib/ovn-util.c | 28 ----------------------------
> > > > lib/ovn-util.h | 1 -
> > > > northd/northd.c | 24 +++++++++---------------
> > > > 3 files changed, 9 insertions(+), 44 deletions(-)
> > > >
> > > > diff --git a/lib/ovn-util.c b/lib/ovn-util.c
> > > > index 6c7629e6d..7b77f838f 100644
> > > > --- a/lib/ovn-util.c
> > > > +++ b/lib/ovn-util.c
> > > > @@ -1283,34 +1283,6 @@ get_lport_type_str(enum en_lport_type lport_type)
> > > > OVS_NOT_REACHED();
> > > > }
> > > >
> > > > -bool
> > > > -is_pb_router_type(const struct sbrec_port_binding *pb)
> > > > -{
> > > > - enum en_lport_type lport_type = get_lport_type(pb);
> > > > -
> > > > - switch (lport_type) {
> > > > - case LP_PATCH:
> > > > - case LP_CHASSISREDIRECT:
> > > > - case LP_L3GATEWAY:
> > > > - case LP_L2GATEWAY:
> > > > - case LP_REMOTE:
> > > > - return true;
> > > > -
> > > > - case LP_VIF:
> > > > - case LP_CONTAINER:
> > > > - case LP_MIRROR:
> > > > - case LP_VIRTUAL:
> > > > - case LP_LOCALNET:
> > > > - case LP_LOCALPORT:
> > > > - case LP_VTEP:
> > > > - case LP_EXTERNAL:
> > > > - case LP_UNKNOWN:
> > > > - return false;
> > > > - }
> > > > -
> > > > - return false;
> > > > -}
> > > > -
> > > > void
> > > > sorted_array_apply_diff(const struct sorted_array *a1,
> > > > const struct sorted_array *a2,
> > > > diff --git a/lib/ovn-util.h b/lib/ovn-util.h
> > > > index 67fc3882d..4c686aac9 100644
> > > > --- a/lib/ovn-util.h
> > > > +++ b/lib/ovn-util.h
> > > > @@ -433,7 +433,6 @@ enum en_lport_type {
> > > >
> > > > enum en_lport_type get_lport_type(const struct sbrec_port_binding *);
> > > > char *get_lport_type_str(enum en_lport_type lport_type);
> > > > -bool is_pb_router_type(const struct sbrec_port_binding *);
> > > >
> > > > /* A wrapper that holds sorted arrays of strings. */
> > > > struct sorted_array {
> > > > diff --git a/northd/northd.c b/northd/northd.c
> > > > index fe5199a86..e1d01df50 100644
> > > > --- a/northd/northd.c
> > > > +++ b/northd/northd.c
> > > > @@ -4982,23 +4982,17 @@ northd_handle_sb_port_binding_changes(
> > > > const struct sbrec_port_binding *pb;
> > > > static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
> > > > SBREC_PORT_BINDING_TABLE_FOR_EACH_TRACKED (pb,
> > > > sbrec_port_binding_table) {
> > > > - bool is_router_port = is_pb_router_type(pb);
> > > > - struct ovn_port *op = NULL;
> > > > -
> > > > - if (is_router_port) {
> > > > - /* A router port binding 'pb' can belong to
> > > > - * - a logical switch port of type router or
> > > > - * - a logical router port.
> > > > - *
> > > > - * So, first search in lr_ports hmap. If not found,
> > > > search in
> > > > - * ls_ports hmap.
> > > > - * */
> > > > - op = ovn_port_find(lr_ports, pb->logical_port);
> > > > - }
> > > > -
> > > > + bool is_router_port = true;
> > > > + /* A router port binding 'pb' can belong to
> > > > + * - a logical switch port of type router or
> > > > + * - a logical router port.
> > > > + *
> > > > + * So, first search in lr_ports hmap. If not found, search in
> > > > + * ls_ports hmap.
> > > > + * */
> > > > + struct ovn_port *op = ovn_port_find(lr_ports,
> > > > pb->logical_port);
> > > > if (!op) {
> > > > op = ovn_port_find(ls_ports, pb->logical_port);
> > > > -
> > > > if (op) {
> > > > is_router_port = false;
> > > > }
> > > > --
> > > > 2.51.0
> > > >
> > > > _______________________________________________
> > > > dev mailing list
> > > > d...@openvswitch.org
> > > > https://mail.openvswitch.org/mailman/listinfo/ovs-dev
> > > _______________________________________________
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> > > d...@openvswitch.org
> > > https://mail.openvswitch.org/mailman/listinfo/ovs-dev
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