Hi Han, Mark, Xavier, On 5/10/22 03:52, Han Zhou wrote: > On Mon, May 9, 2022 at 5:36 PM Xavier Simonart <xsimo...@redhat.com> wrote: >> >> 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/20220401101640.1139426-1-xsimo...@redhat.com/ >> > https://patchwork.ozlabs.org/project/ovn/patch/20220401101640.1139426-1-xsimo...@redhat.com/ > 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. I am interested in the solution you are working on. > I also want to add that my patch here is to provide a generic solution that > filters out the changes we don't care about and quits the I-P engine > processing early. It can be extended easily in the future if we have new > changes to ignore. In many cases this has been achieved by omitting columns > in OVSDB IDL monitoring, but the case here is that we care about part of a > column that is with k-v pairs and OVSDB IDL can monitor/omit the whole > column. So I feel we may need this regardless of the new solution that > addresses the consecutively multiple ports binding problem.
I think so too. If I understand correctly we need both changes. > Anyway, we can wait and evaluate when your new patch is posted. > +1 Thanks, Dumitru > Thanks, > Han > >> >> Thanks >> Xavier >> >> >> On Mon, May 9, 2022 at 9:32 PM Mark Michelson <mmich...@redhat.com> 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/20220401101640.1139426-1-xsimo...@redhat.com/ >>> , 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 <hz...@ovn.org> >>>> --- >>>> 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 d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev
