On 5/3/22 21:37, 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 <hz...@ovn.org>
Hi Han,
Thanks for the fix!
I would add:
Fixes: 4d3cb42b076b ("binding: Set Logical_Switch_Port.up when all OVS flows
are installed.")
I have another tiny comment below. I'm currently rerunning the
ovn-kuberenetes tests with your patch applied [0] because the run done
by ovsrobot failed to bring up a cluster [1] and I want to make sure
we're not breaking anything.
Thanks,
Dumitru
[0] https://github.com/dceara/ovn/actions/runs/2312210800
[1]
https://github.com/ovsrobot/ovn/runs/6280999584?check_suite_focus=true#step:9:725
> ---
> 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);
Nit: no need for SHASH_FOR_EACH_SAFE as far as I can tell.
> + }
> + 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
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