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.
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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