On Wed, Nov 26, 2025 at 9:16 AM Dumitru Ceara <[email protected]> wrote:

> On 11/25/25 6:11 PM, Ales Musil wrote:
> > Do a partial revert of the I-P handling for LR addition and deletion.
> > This causes issues with DP groups processing, when there new flows
> > added northd is still holding multiple references to the existing DP
> > group. In that case we cannot resize it, because we don't know if the
> > DP group will split. This might lead to DP groups being deleted and
> > recreated as we slowly remove the references and at the end all flows
> > migrated to the new DP group leaving the old one empty. This is
> > particularly bad for SB performance as we are hammering it with DP
> > group creation/deletion + updates of DP group references in all
> > affected flows.
> >
> > The lflows_ref is intentionally left NULL in the ovn_datapath struct
> > so we don't have to revert all those changes to pass it along, and
> > so we don't waste any space to maintain them as they are not used
> > by anything right now.
> >
> > This reverts commit 9ec96d0d85b66a6d2c9e66da694c9cfe710bdf46.
> > This reverts commit cf92fb76ed487862054b8d10c89a46f5fb796072.
> >
> > Signed-off-by: Ales Musil <[email protected]>
> > ---
>
> Hi Ales,
>

Hi Dumitru,
thank you for the review.


> Thanks for the patch.  The change looks good to me but should we also
> add a test that ensures the datapath groups don't get recreated when a
> logical router is added?
>

 Yes that makes sense, I'll extend the test that we have for DPG over LS.


> Regards,
> Dumitru
>
> >  northd/en-lflow.c   | 11 +++----
> >  northd/northd.c     | 71 ---------------------------------------------
> >  northd/northd.h     |  7 +++--
> >  tests/ovn-northd.at |  5 ++--
> >  4 files changed, 12 insertions(+), 82 deletions(-)
> >
> > diff --git a/northd/en-lflow.c b/northd/en-lflow.c
> > index 30bf7e35c..fcccc6265 100644
> > --- a/northd/en-lflow.c
> > +++ b/northd/en-lflow.c
> > @@ -149,19 +149,16 @@ lflow_northd_handler(struct engine_node *node,
> >          return EN_UNHANDLED;
> >      }
> >
> > +    if (northd_has_lrouters_in_tracked_data(&northd_data->trk_data)) {
> > +        return EN_UNHANDLED;
> > +    }
> > +
> >      const struct engine_context *eng_ctx = engine_get_context();
> >      struct lflow_data *lflow_data = data;
> >
> >      struct lflow_input lflow_input;
> >      lflow_get_input_data(node, &lflow_input);
> >
> > -    if (!lflow_handle_northd_lr_changes(eng_ctx->ovnsb_idl_txn,
> > -
> &northd_data->trk_data.trk_routers,
> > -                                        &lflow_input,
> > -                                        lflow_data->lflow_table)) {
> > -        return EN_UNHANDLED;
> > -    }
> > -
> >      if (!lflow_handle_northd_port_changes(eng_ctx->ovnsb_idl_txn,
> >
> &northd_data->trk_data.trk_lsps,
> >                                            &lflow_input,
> > diff --git a/northd/northd.c b/northd/northd.c
> > index 011f449ec..eb85a79cb 100644
> > --- a/northd/northd.c
> > +++ b/northd/northd.c
> > @@ -556,7 +556,6 @@ ovn_datapath_create(struct hmap *datapaths, const
> struct uuid *key,
> >      od->ipam_info_initialized = false;
> >      od->tunnel_key = sdp->sb_dp->tunnel_key;
> >      init_mcast_info_for_datapath(od);
> > -    od->datapath_lflows = lflow_ref_create();
> >      return od;
> >  }
> >
> > @@ -585,7 +584,6 @@ ovn_datapath_destroy(struct ovn_datapath *od)
> >          destroy_mcast_info_for_datapath(od);
> >          destroy_ports_for_datapath(od);
> >          sset_destroy(&od->router_ips);
> > -        lflow_ref_destroy(od->datapath_lflows);
> >          free(od);
> >      }
> >  }
> > @@ -19256,7 +19254,6 @@ lflow_reset_northd_refs(struct lflow_input
> *lflow_input)
> >      struct ls_stateful_record *ls_stateful_rec;
> >      struct ovn_lb_datapaths *lb_dps;
> >      struct ovn_port *op;
> > -    const struct ovn_datapath *od;
> >
> >      LR_STATEFUL_TABLE_FOR_EACH (lr_stateful_rec,
> >                                  lflow_input->lr_stateful_table) {
> > @@ -19281,74 +19278,6 @@ lflow_reset_northd_refs(struct lflow_input
> *lflow_input)
> >      HMAP_FOR_EACH (lb_dps, hmap_node, lflow_input->lb_datapaths_map) {
> >          lflow_ref_clear(lb_dps->lflow_ref);
> >      }
> > -
> > -    HMAP_FOR_EACH (od, key_node, &lflow_input->lr_datapaths->datapaths)
> {
> > -        lflow_ref_clear(od->datapath_lflows);
> > -    }
> > -
> > -    HMAP_FOR_EACH (od, key_node, &lflow_input->ls_datapaths->datapaths)
> {
> > -        lflow_ref_clear(od->datapath_lflows);
> > -    }
> > -}
> > -
> > -bool
> > -lflow_handle_northd_lr_changes(struct ovsdb_idl_txn *ovnsb_txn,
> > -                                struct tracked_dps *tracked_lrs,
> > -                                struct lflow_input *lflow_input,
> > -                                struct lflow_table *lflows)
> > -{
> > -    bool handled = true;
> > -    struct hmapx_node *hmapx_node;
> > -    HMAPX_FOR_EACH (hmapx_node, &tracked_lrs->deleted) {
> > -        struct ovn_datapath *od = hmapx_node->data;
> > -        handled = lflow_ref_resync_flows(
> > -            od->datapath_lflows, lflows, ovnsb_txn,
> lflow_input->ls_datapaths,
> > -            lflow_input->lr_datapaths,
> > -            lflow_input->ovn_internal_version_changed,
> > -            lflow_input->sbrec_logical_flow_table,
> > -            lflow_input->sbrec_logical_dp_group_table);
> > -        if (!handled) {
> > -            return handled;
> > -        }
> > -    }
> > -
> > -    struct lswitch_flow_build_info lsi = {
> > -        .lr_datapaths = lflow_input->lr_datapaths,
> > -        .lr_stateful_table = lflow_input->lr_stateful_table,
> > -        .lflows =lflows,
> > -        .route_data = lflow_input->route_data,
> > -        .route_tables = lflow_input->route_tables,
> > -        .route_policies = lflow_input->route_policies,
> > -        .match = DS_EMPTY_INITIALIZER,
> > -        .actions = DS_EMPTY_INITIALIZER,
> > -    };
> > -    HMAPX_FOR_EACH (hmapx_node, &tracked_lrs->crupdated) {
> > -        struct ovn_datapath *od = hmapx_node->data;
> > -
> > -        lflow_ref_unlink_lflows(od->datapath_lflows);
> > -        build_lswitch_and_lrouter_iterate_by_lr(od, &lsi);
> > -    }
> > -
> > -    /* We need to make sure that all datapath groups are allocated
> before
> > -     * trying to sync logical flows. Otherwise, we would need to
> recompute
> > -     * those datapath groups within those flows over and over again. */
> > -    HMAPX_FOR_EACH (hmapx_node, &tracked_lrs->crupdated) {
> > -        struct ovn_datapath *od = hmapx_node->data;
> > -
> > -        handled = lflow_ref_sync_lflows(
> > -            od->datapath_lflows, lflows, ovnsb_txn,
> lflow_input->ls_datapaths,
> > -            lflow_input->lr_datapaths,
> > -            lflow_input->ovn_internal_version_changed,
> > -            lflow_input->sbrec_logical_flow_table,
> > -            lflow_input->sbrec_logical_dp_group_table);
> > -        if (!handled) {
> > -            break;
> > -        }
> > -    }
> > -
> > -    ds_destroy(&lsi.actions);
> > -    ds_destroy(&lsi.match);
> > -    return handled;
> >  }
> >
> >  bool
> > diff --git a/northd/northd.h b/northd/northd.h
> > index 32134d36e..40d845e4f 100644
> > --- a/northd/northd.h
> > +++ b/northd/northd.h
> > @@ -473,8 +473,11 @@ struct ovn_datapath {
> >      /* Map of ovn_port objects belonging to this datapath.
> >       * This map doesn't include derived ports. */
> >      struct hmap ports;
> > -    /* Reference to the lflows belonging to this datapath currently
> router
> > -     * only lflows. */
> > +
> > +    /* XXX Reference to the lflows belonging to this datapath currently
> router
> > +     * only lflows. This is NULL for now just to not waste any space
> > +     * as it's not used by anything right now, but it wasn't worth
> reverting
> > +     * all the related changes. */
> >      struct lflow_ref *datapath_lflows;
> >  };
> >
> > diff --git a/tests/ovn-northd.at b/tests/ovn-northd.at
> > index f7ec6a33a..7b1779569 100644
> > --- a/tests/ovn-northd.at
> > +++ b/tests/ovn-northd.at
> > @@ -12627,17 +12627,18 @@ check_engine_stats lr_nat norecompute compute
> >  check_engine_stats lr_stateful norecompute compute
> >  check_engine_stats sync_to_sb_pb norecompute compute
> >  check_engine_stats sync_to_sb_lb norecompute compute
> > -check_engine_stats lflow norecompute compute
> > +check_engine_stats lflow recompute nocompute
> >  CHECK_NO_CHANGE_AFTER_RECOMPUTE
> >
> >  check as northd ovn-appctl -t ovn-northd inc-engine/clear-stats
> >  check ovn-nbctl --wait=sb lr-del lr0
> > +
> >  check_engine_stats northd norecompute compute
> >  check_engine_stats lr_nat norecompute compute
> >  check_engine_stats lr_stateful norecompute compute
> >  check_engine_stats sync_to_sb_pb norecompute compute
> >  check_engine_stats sync_to_sb_lb norecompute compute
> > -check_engine_stats lflow norecompute compute
> > +check_engine_stats lflow recompute nocompute
> >  CHECK_NO_CHANGE_AFTER_RECOMPUTE
> >
> >  check ovn-nbctl --wait=sb lr-add lr0
>
>
Regards,
Ales
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