Hi Mark, Han Thanks for looking into this. Han's patch is addressing the issues I initially tried fixing with https://patchwork.ozlabs.org/project/ovn/patch/[email protected]/ https://patchwork.ozlabs.org/project/ovn/patch/[email protected]/ is definitely not a good solution (incurs some delay and is more a workaround than a fix).
I have been trying to follow another approach, which would fix a slightly broader issue. The goal is to try to avoid recomputes when updating Port_Binding in SBDB. In addition to the case Han (greatly) described, we also hit some recomputes when the same controller binds multiple ports quite quickly consecutively. So I have been trying to extend the approach used in if-status (i.e. not write to SBDB if SBDB is read-only, and have the if-status state machine running through the different interface states, update SBDB when possible, and change the states). I have a patch (almost) ready but had some issues with some test cases, and was still investigating whether those issues were due to my patch.... I hope to post it tomorrow. We can then discuss whether we need both approaches. Thanks Xavier On Mon, May 9, 2022 at 9:32 PM Mark Michelson <[email protected]> wrote: > Based on the explanation and the code, this seems to solve the problem > of the spurious recomputes. I'd like confirmation from Xavier that this > is fixing the issue he was addressing in > > https://patchwork.ozlabs.org/project/ovn/patch/[email protected]/ > , and I'd also like confirmation that this approach doesn't incur the > delays that Dumitru mentioned on Xavier's patch. > > With those confirmations, I'll add my ack to this patch. > > On 5/3/22 15:37, Han Zhou wrote: > > During the process of claiming a VIF port on a chassis, there are > > multiple SB and local OVSDB updates by ovn-controller, which may trigger > > ovn-controller recompute, depending on the timing between the completion > > of SB and local OVSDB updates: > > > > After port claiming, ovn-controller sends an update to the local OVSDB > > to clean the Interface:external_ids:ovn-installed, and also sends an > > update to the SB DB to update the Port_Binding:chassis. If the local > > OVSDB update notification comes back before the SB update completes, > > ovn-controller's SB IDL is still "in transaction" and read-only, but the > > local Interface update triggers the I-P engine runtime_data node to > > handle the OVS_interface change, which considers the VIF to be claimed > > (again) potentially, which requires SB updates while it is not possible > > at the moment, and so the I-P handler returns failure and the engine > > aborts, which triggers recompute at the next I-P engine iteration when > > SB DB is writable. > > > > If we are lucky at the above step that the SB update completes before > > the local OVSDB update is received, ovn-controller would handle the > > change incrementally (and figures out that the SB Port_Binding chassis > > is already the current one thus wouldn't reclaim the VIF). But the next > > step after it completes flow computing for the newly bound VIF it sends > > another update to the local OVSDB to set the > > Interface:external_ids:ovn-installed and ovn-installed-ts, while at the > > same time it also sends an update to the SB DB to set the > > Port_Binding:up. These two parallel updates would lead to the same > > situation as the above step and potentially cause ovn-controll > > recompute. > > > > The recompute is very likely to be triggered in production because the > > SB DB is remote (on central nodes) and has heavier load, which requires > > longer time to complete the updates than the local OVSDB server. > > > > The problem is that the runtime_data's OVS_interface change handler > > couldn't handle the update of the Interface:external_ids:ovn-installed > > incrementally, because ovn-controller assumes it could require an SB > > update that is not possible at the moment. However, the assumption is > > not true. In fact it shouldn't even care about the change because this > > external_id:ovn-installed is written by ovn-controller itself and it is > > write-only (no need to read it as an input for any further processing). > > > > So, the idea to fix the problem is to ignore such changes that happen to > > the "write-only" fields only. OVSDB change tracking provides APIs to > > check if a specific column is updated, but the difficulty here is that > > the column external_ids is a k-v map which contains not only the data > > that ovn-controller can ignore, such as ovn-installed, ovn-installed-ts, > > but also the data ovn-controller cares about, such as iface-id, > > iface-id-ver and encap-ip. To solve this problem, we need to know what's > > changed exactly inside the external_ids map. > > > > This patch solves it by introducing a new I-P engine node > > ovs_interface_shadow to wrap the OVSDB input ovs_interface with an extra > > copy of the older version of the column external_ids, and replace the > > input OVS_interface of the runtime_data node. In the change handler of > the > > runtime_data node we evaluates if the change needs to be handled before > > calling consider_iface_claim(), so in the above scenarios the changes > > don't need to be handled and won't trigger recompute any more. A test > > case is also updated to capture this (which is very likely, if not 100%, > > to fail without the fix). > > > > Signed-off-by: Han Zhou <[email protected]> > > --- > > v2: Add comments that was missing while committing v1. > > > > controller/binding.c | 70 ++++++++++++++++++++++++ > > controller/binding.h | 1 + > > controller/ovn-controller.c | 105 +++++++++++++++++++++++++++++++++--- > > tests/ovn-performance.at | 17 ++++++ > > 4 files changed, 186 insertions(+), 7 deletions(-) > > > > diff --git a/controller/binding.c b/controller/binding.c > > index 7281b0485..0563d9d1e 100644 > > --- a/controller/binding.c > > +++ b/controller/binding.c > > @@ -1907,6 +1907,71 @@ is_iface_in_int_bridge(const struct > ovsrec_interface *iface, > > return false; > > } > > > > +static bool > > +is_ext_id_changed(const struct smap *a, const struct smap *b, const > char *key) > > +{ > > + const char *value_a = smap_get(a, key); > > + const char *value_b = smap_get(b, key); > > + if ((value_a && !value_b) > > + || (!value_a && value_b) > > + || (value_a && value_b && strcmp(value_a, value_b))) { > > + return true; > > + } > > + return false; > > +} > > + > > +/* Check if the change in 'iface_rec' is something we are interested in > from > > + * port binding perspective. Return true if the change needs to be > handled, > > + * otherwise return false. > > + * > > + * The 'iface_rec' must be change tracked, i.e. iterator from > > + * OVSREC_INTERFACE_TABLE_FOR_EACH_TRACKED. */ > > +static bool > > +ovs_interface_change_need_handle(const struct ovsrec_interface > *iface_rec, > > + struct shash > *iface_table_external_ids_old) > > +{ > > + if (ovsrec_interface_is_updated(iface_rec, > > + OVSREC_INTERFACE_COL_NAME)) { > > + return true; > > + } > > + if (ovsrec_interface_is_updated(iface_rec, > > + OVSREC_INTERFACE_COL_OFPORT)) { > > + return true; > > + } > > + if (ovsrec_interface_is_updated(iface_rec, > > + OVSREC_INTERFACE_COL_TYPE)) { > > + return true; > > + } > > + if (ovsrec_interface_is_updated(iface_rec, > > + OVSREC_INTERFACE_COL_EXTERNAL_IDS)) > { > > + /* Compare the external_ids that we are interested in with the > old > > + * values: > > + * - iface-id > > + * - iface-id-ver > > + * - encap-ip > > + * For any other changes, such as ovn-installed, > ovn-installed-ts, etc, > > + * we don't need to handle. */ > > + struct smap *external_ids_old = > > + shash_find_data(iface_table_external_ids_old, > iface_rec->name); > > + if (!external_ids_old) { > > + return true; > > + } > > + if (is_ext_id_changed(&iface_rec->external_ids, > external_ids_old, > > + "iface-id")) { > > + return true; > > + } > > + if (is_ext_id_changed(&iface_rec->external_ids, > external_ids_old, > > + "iface-id-ver")) { > > + return true; > > + } > > + if (is_ext_id_changed(&iface_rec->external_ids, > external_ids_old, > > + "encap-ip")) { > > + return true; > > + } > > + } > > + return false; > > +} > > + > > /* Returns true if the ovs interface changes were handled successfully, > > * false otherwise. > > */ > > @@ -2018,6 +2083,11 @@ binding_handle_ovs_interface_changes(struct > binding_ctx_in *b_ctx_in, > > continue; > > } > > > > + if (!ovs_interface_change_need_handle( > > + iface_rec, b_ctx_in->iface_table_external_ids_old)) { > > + continue; > > + } > > + > > const char *iface_id = smap_get(&iface_rec->external_ids, > "iface-id"); > > int64_t ofport = iface_rec->n_ofport ? *iface_rec->ofport : 0; > > if (iface_id && ofport > 0 && > > diff --git a/controller/binding.h b/controller/binding.h > > index 430a8d9b1..e49e1ebb6 100644 > > --- a/controller/binding.h > > +++ b/controller/binding.h > > @@ -55,6 +55,7 @@ struct binding_ctx_in { > > const struct ovsrec_bridge_table *bridge_table; > > const struct ovsrec_open_vswitch_table *ovs_table; > > const struct ovsrec_interface_table *iface_table; > > + struct shash *iface_table_external_ids_old; > > }; > > > > /* Locally relevant port bindings, e.g., VIFs that might be bound > locally, > > diff --git a/controller/ovn-controller.c b/controller/ovn-controller.c > > index 22b7fa935..649353f7d 100644 > > --- a/controller/ovn-controller.c > > +++ b/controller/ovn-controller.c > > @@ -1042,6 +1042,91 @@ en_ofctrl_is_connected_run(struct engine_node > *node, void *data) > > engine_set_node_state(node, EN_UNCHANGED); > > } > > > > +/* This engine node is to wrap the OVS_interface input and maintain a > copy of > > + * the old version of data for the column external_ids. > > + * > > + * There are some special considerations of this engine node: > > + * 1. It has a single input OVS_interface, and it transparently passes > the > > + * input changes as its own output data to its dependants. So there > is no > > + * processing to OVS_interface changes but simply mark the node > status as > > + * UPDATED (and so the run() and the change handler is the same). > > + * 2. The iface_table_external_ids_old is computed/updated in the member > > + * clear_tracked_data(), because that is when the last round of > processing > > + * has completed but the new IDL data is yet to refresh, so we > replace the > > + * old data with the current data. */ > > +struct ed_type_ovs_interface_shadow { > > + struct ovsrec_interface_table *iface_table; > > + struct shash iface_table_external_ids_old; > > +}; > > + > > +static void * > > +en_ovs_interface_shadow_init(struct engine_node *node OVS_UNUSED, > > + struct engine_arg *arg OVS_UNUSED) > > +{ > > + struct ed_type_ovs_interface_shadow *data = xzalloc(sizeof *data); > > + data->iface_table = NULL; > > + shash_init(&data->iface_table_external_ids_old); > > + > > + return data; > > +} > > + > > +static void > > +iface_table_external_ids_old_destroy(struct shash *table_ext_ids) > > +{ > > + struct shash_node *node; > > + SHASH_FOR_EACH_SAFE (node, table_ext_ids) { > > + struct smap *ext_ids = node->data; > > + smap_destroy(ext_ids); > > + } > > + shash_destroy_free_data(table_ext_ids); > > +} > > + > > +static void > > +en_ovs_interface_shadow_cleanup(void *data_) > > +{ > > + struct ed_type_ovs_interface_shadow *data = data_; > > + > iface_table_external_ids_old_destroy(&data->iface_table_external_ids_old); > > +} > > + > > +static void > > +en_ovs_interface_shadow_clear_tracked_data(void *data_) > > +{ > > + struct ed_type_ovs_interface_shadow *data = data_; > > + > iface_table_external_ids_old_destroy(&data->iface_table_external_ids_old); > > + shash_init(&data->iface_table_external_ids_old); > > + > > + if (!data->iface_table) { > > + return; > > + } > > + > > + const struct ovsrec_interface *iface_rec; > > + OVSREC_INTERFACE_TABLE_FOR_EACH (iface_rec, data->iface_table) { > > + struct smap *external_ids = xmalloc(sizeof *external_ids); > > + smap_clone(external_ids, &iface_rec->external_ids); > > + shash_add(&data->iface_table_external_ids_old, iface_rec->name, > > + external_ids); > > + } > > +} > > + > > +static void > > +en_ovs_interface_shadow_run(struct engine_node *node, void *data_) > > +{ > > + struct ed_type_ovs_interface_shadow *data = data_; > > + struct ovsrec_interface_table *iface_table = > > + (struct ovsrec_interface_table *)EN_OVSDB_GET( > > + engine_get_input("OVS_interface", node)); > > + data->iface_table = iface_table; > > + engine_set_node_state(node, EN_UPDATED); > > +} > > + > > +static bool > > +ovs_interface_shadow_ovs_interface_handler(struct engine_node *node, > > + void *data_) > > +{ > > + en_ovs_interface_shadow_run(node, data_); > > + return true; > > +} > > + > > struct ed_type_runtime_data { > > /* Contains "struct local_datapath" nodes. */ > > struct hmap local_datapaths; > > @@ -1214,9 +1299,8 @@ init_binding_ctx(struct engine_node *node, > > (struct ovsrec_port_table *)EN_OVSDB_GET( > > engine_get_input("OVS_port", node)); > > > > - struct ovsrec_interface_table *iface_table = > > - (struct ovsrec_interface_table *)EN_OVSDB_GET( > > - engine_get_input("OVS_interface", node)); > > + struct ed_type_ovs_interface_shadow *iface_shadow = > > + engine_get_input_data("ovs_interface_shadow", node); > > > > struct ovsrec_qos_table *qos_table = > > (struct ovsrec_qos_table *)EN_OVSDB_GET( > > @@ -1249,7 +1333,9 @@ init_binding_ctx(struct engine_node *node, > > b_ctx_in->sbrec_port_binding_by_datapath = > sbrec_port_binding_by_datapath; > > b_ctx_in->sbrec_port_binding_by_name = sbrec_port_binding_by_name; > > b_ctx_in->port_table = port_table; > > - b_ctx_in->iface_table = iface_table; > > + b_ctx_in->iface_table = iface_shadow->iface_table; > > + b_ctx_in->iface_table_external_ids_old = > > + &iface_shadow->iface_table_external_ids_old; > > b_ctx_in->qos_table = qos_table; > > b_ctx_in->port_binding_table = pb_table; > > b_ctx_in->br_int = br_int; > > @@ -1331,7 +1417,7 @@ en_runtime_data_run(struct engine_node *node, void > *data) > > } > > > > static bool > > -runtime_data_ovs_interface_handler(struct engine_node *node, void *data) > > +runtime_data_ovs_interface_shadow_handler(struct engine_node *node, > void *data) > > { > > struct ed_type_runtime_data *rt_data = data; > > struct binding_ctx_in b_ctx_in; > > @@ -3338,6 +3424,8 @@ main(int argc, char *argv[]) > > > > /* Define inc-proc-engine nodes. */ > > ENGINE_NODE_WITH_CLEAR_TRACK_DATA_IS_VALID(ct_zones, "ct_zones"); > > + ENGINE_NODE_WITH_CLEAR_TRACK_DATA(ovs_interface_shadow, > > + "ovs_interface_shadow"); > > ENGINE_NODE_WITH_CLEAR_TRACK_DATA(runtime_data, "runtime_data"); > > ENGINE_NODE(non_vif_data, "non_vif_data"); > > ENGINE_NODE(mff_ovn_geneve, "mff_ovn_geneve"); > > @@ -3459,6 +3547,9 @@ main(int argc, char *argv[]) > > engine_add_input(&en_ct_zones, &en_runtime_data, > > ct_zones_runtime_data_handler); > > > > + engine_add_input(&en_ovs_interface_shadow, &en_ovs_interface, > > + ovs_interface_shadow_ovs_interface_handler); > > + > > engine_add_input(&en_runtime_data, &en_ofctrl_is_connected, NULL); > > > > engine_add_input(&en_runtime_data, &en_ovs_open_vswitch, NULL); > > @@ -3480,8 +3571,8 @@ main(int argc, char *argv[]) > > */ > > engine_add_input(&en_runtime_data, &en_ovs_port, > > engine_noop_handler); > > - engine_add_input(&en_runtime_data, &en_ovs_interface, > > - runtime_data_ovs_interface_handler); > > + engine_add_input(&en_runtime_data, &en_ovs_interface_shadow, > > + runtime_data_ovs_interface_shadow_handler); > > > > engine_add_input(&en_flow_output, &en_lflow_output, > > flow_output_lflow_output_handler); > > diff --git a/tests/ovn-performance.at b/tests/ovn-performance.at > > index bc133f93b..9affca498 100644 > > --- a/tests/ovn-performance.at > > +++ b/tests/ovn-performance.at > > @@ -366,6 +366,23 @@ for i in 1 2; do > > ovn-nbctl wait-until Logical_Switch_Port $lp 'up=true' && > > ovn-nbctl --wait=hv sync] > > ) > > + > > + # Delete and recreate $lp to make it unbind and rebind multiple > times, and > > + # ensure no recompute is triggered. > > + for k in $(seq 10); do > > + OVN_CONTROLLER_EXPECT_NO_HIT( > > + [hv$i hv$j], [lflow_run], > > + [as hv$i ovs-vsctl set Interface $vif > external-ids:iface-id=xxxx && > > + ovn-nbctl wait-until Logical_Switch_Port $lp 'up=false' && > > + ovn-nbctl --wait=hv sync] > > + ) > > + OVN_CONTROLLER_EXPECT_NO_HIT( > > + [hv$i hv$j], [lflow_run], > > + [as hv$i ovs-vsctl set Interface $vif > external-ids:iface-id=$lp && > > + ovn-nbctl wait-until Logical_Switch_Port $lp 'up=true' && > > + ovn-nbctl --wait=hv sync] > > + ) > > + done > > done > > > > for i in 1 2; do > > > > _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
