On 17/02/2021 19:33, Lorenzo Bianconi wrote:

Should the subject have an underscore? 'coverage_counters'

> In order to help understanding system behaviour for debugging purpose,
> introduce coverage counters for run handlers of ovn-controller
> I-P engine nodes. Moreover add a global counter for engine abort.
> 
> https://bugzilla.redhat.com/show_bug.cgi?id=1890902
> Signed-off-by: Lorenzo Bianconi <[email protected]>
> ---
> Changes since v1:
> - drop handler counters and add global abort counter
> - improve documentation and naming scheme
> - introduce engine_set_node_updated utility macro
> ---
>  controller/ovn-controller.c | 39 +++++++++++++++++++++++++++----------
>  lib/inc-proc-eng.c          |  5 +++++
>  lib/inc-proc-eng.h          | 12 +++++++++++-
>  3 files changed, 45 insertions(+), 11 deletions(-)
> 
> diff --git a/controller/ovn-controller.c b/controller/ovn-controller.c
> index 4343650fc..42eed9ebd 100644
> --- a/controller/ovn-controller.c
> +++ b/controller/ovn-controller.c
> @@ -69,6 +69,7 @@
>  #include "stopwatch.h"
>  #include "lib/inc-proc-eng.h"
>  #include "hmapx.h"
> +#include "coverage.h"
>  
>  VLOG_DEFINE_THIS_MODULE(main);
>  
> @@ -85,6 +86,18 @@ static unixctl_cb_func lflow_cache_flush_cmd;
>  static unixctl_cb_func lflow_cache_show_stats_cmd;
>  static unixctl_cb_func debug_delay_nb_cfg_report;
>  
> +/* Coverage counters for run handlers of OVN controller
> + * incremental processing nodes
> + */
> +ENGINE_RUN_COVERAGE_DEFINE(flow_output);
> +ENGINE_RUN_COVERAGE_DEFINE(runtime_data);
> +ENGINE_RUN_COVERAGE_DEFINE(addr_sets);
> +ENGINE_RUN_COVERAGE_DEFINE(port_groups);
> +ENGINE_RUN_COVERAGE_DEFINE(ct_zones);
> +ENGINE_RUN_COVERAGE_DEFINE(mff_ovn_geneve);
> +ENGINE_RUN_COVERAGE_DEFINE(ofctrl_is_connected);
> +ENGINE_RUN_COVERAGE_DEFINE(physical_flow_changes);


I would like these counters to be part of the framework (i.e.
inc-proc-eng.c/h) rather than being exposed out. The reasoning is that
we shouldn't rely on a developer to modify them correctly when updating
the _handler() and the _run() functions as it is too error-prone IMHO.
For example, if a _run() function exits early and also sets a node to
updated or aborts a node, will the developer/reviewer remember to update
the corresponding counter? Also, if we need to make changes to the
counters, it would be preferable to make the changes in one location.

I realize that this causes issues for per-node counters as currently
implemented: inc-proc-eng.c has no idea about which nodes are which at
compilation time and COVERAGE_INC() is a macro which requires templating
the name of the node at compilation time.

For this reason, I suggest the following:

* Add counters to 'struct engine_node' and/or 'struct engine_context'
* Create an ovs-appctl command, something like `ovs-appctl-ctl -t
ovs-controller inc-proc-eng/stats-show` and `ovs-appctl-ctl -t
ovs-controller inc-proc-eng/stats-clear` that will show/clear these
stats to the user

This follows a common pattern in OVS/OVN code. e.g.
https://github.com/openvswitch/ovs/blob/master/Documentation/topics/dpdk/pmd.rst#pmd-thread-statistics.

The next question is what counters to expose. As I think it should be
easier to expose counters using the `appctl` above, I would suggest
exposing as much as you can. However, you could also get feedback from
those in the community who have more operational experience with OVN.

Here are some suggestions:

* Total number of engine runs
* Total number of engine aborts
* Total number of engine recomputes
* Number of runs for each node
* Number of computes for each node
* Number of recomputes for each node
* Number of transitions to ABORT for each node
* Number of transitions to UNCHANGED for each node
* Number of transitions to UPDATED for each node

What do you think?

> +
>  #define DEFAULT_BRIDGE_NAME "br-int"
>  #define DEFAULT_PROBE_INTERVAL_MSEC 5000
>  #define OFCTRL_DEFAULT_PROBE_INTERVAL_SEC 0
> @@ -955,6 +968,10 @@ ctrl_register_ovs_idl(struct ovsdb_idl *ovs_idl)
>      SB_NODE(dns, "dns") \
>      SB_NODE(load_balancer, "load_balancer")
>  
> +#define SB_NODE(NAME, NAME_STR) ENGINE_RUN_COVERAGE_DEFINE(sb_##NAME);
> +    SB_NODES
> +#undef SB_NODE
> +
>  enum sb_engine_node {
>  #define SB_NODE(NAME, NAME_STR) SB_##NAME,
>      SB_NODES
> @@ -972,6 +989,10 @@ enum sb_engine_node {
>      OVS_NODE(interface, "interface") \
>      OVS_NODE(qos, "qos")
>  
> +#define OVS_NODE(NAME, NAME_STR) ENGINE_RUN_COVERAGE_DEFINE(ovs_##NAME);
> +    OVS_NODES
> +#undef OVS_NODE
> +
>  enum ovs_engine_node {
>  #define OVS_NODE(NAME, NAME_STR) OVS_##NAME,
>      OVS_NODES
> @@ -1011,7 +1032,7 @@ en_ofctrl_is_connected_run(struct engine_node *node, 
> void *data)
>              ofctrl_seqno_flush();
>              binding_seqno_flush();
>          }
> -        engine_set_node_state(node, EN_UPDATED);
> +        engine_set_node_updated(node, ofctrl_is_connected);
>          return;
>      }
>      engine_set_node_state(node, EN_UNCHANGED);
> @@ -1067,7 +1088,7 @@ en_addr_sets_run(struct engine_node *node, void *data)
>      addr_sets_init(as_table, &as->addr_sets);
>  
>      as->change_tracked = false;
> -    engine_set_node_state(node, EN_UPDATED);
> +    engine_set_node_updated(node, addr_sets);
>  }
>  
>  static bool
> @@ -1147,7 +1168,7 @@ en_port_groups_run(struct engine_node *node, void *data)
>      port_groups_init(pg_table, &pg->port_groups);
>  
>      pg->change_tracked = false;
> -    engine_set_node_state(node, EN_UPDATED);
> +    engine_set_node_updated(node, port_groups);
>  }
>  
>  static bool
> @@ -1482,7 +1503,7 @@ en_runtime_data_run(struct engine_node *node, void 
> *data)
>  
>      binding_run(&b_ctx_in, &b_ctx_out);
>  
> -    engine_set_node_state(node, EN_UPDATED);
> +    engine_set_node_updated(node, runtime_data);
>  }
>  
>  static bool
> @@ -1604,8 +1625,7 @@ en_ct_zones_run(struct engine_node *node, void *data)
>                      &ct_zones_data->current, ct_zones_data->bitmap,
>                      &ct_zones_data->pending, &rt_data->ct_updated_datapaths);
>  
> -
> -    engine_set_node_state(node, EN_UPDATED);
> +    engine_set_node_updated(node, ct_zones);
>  }
>  
>  /* The data in the ct_zones node is always valid (i.e., no stale pointers). 
> */
> @@ -1639,7 +1659,7 @@ en_mff_ovn_geneve_run(struct engine_node *node, void 
> *data)
>      enum mf_field_id mff_ovn_geneve = ofctrl_get_mf_field_id();
>      if (ed_mff_ovn_geneve->mff_ovn_geneve != mff_ovn_geneve) {
>          ed_mff_ovn_geneve->mff_ovn_geneve = mff_ovn_geneve;
> -        engine_set_node_state(node, EN_UPDATED);
> +        engine_set_node_updated(node, mff_ovn_geneve);
>          return;
>      }
>      engine_set_node_state(node, EN_UNCHANGED);
> @@ -1714,7 +1734,7 @@ en_physical_flow_changes_run(struct engine_node *node, 
> void *data)
>  {
>      struct ed_type_pfc_data *pfc_tdata = data;
>      pfc_tdata->recompute_physical_flows = true;
> -    engine_set_node_state(node, EN_UPDATED);
> +    engine_set_node_updated(node, physical_flow_changes);
>  }
>  
>  /* ct_zone changes are not handled incrementally but a handler is required
> @@ -2034,8 +2054,7 @@ en_flow_output_run(struct engine_node *node, void *data)
>      init_physical_ctx(node, rt_data, &p_ctx);
>  
>      physical_run(&p_ctx, &fo->flow_table);
> -
> -    engine_set_node_state(node, EN_UPDATED);
> +    engine_set_node_updated(node, flow_output);
>  }
>  
>  static bool
> diff --git a/lib/inc-proc-eng.c b/lib/inc-proc-eng.c
> index 916dbbe39..a19ad68f8 100644
> --- a/lib/inc-proc-eng.c
> +++ b/lib/inc-proc-eng.c
> @@ -27,6 +27,7 @@
>  #include "openvswitch/hmap.h"
>  #include "openvswitch/vlog.h"
>  #include "inc-proc-eng.h"
> +#include "coverage.h"
>  
>  VLOG_DEFINE_THIS_MODULE(inc_proc_eng);
>  
> @@ -44,6 +45,9 @@ static const char *engine_node_state_name[EN_STATE_MAX] = {
>      [EN_ABORTED]   = "Aborted",
>  };
>  
> +/* global counter for engine abort */
> +COVERAGE_DEFINE(engine_abort);
> +
>  void
>  engine_set_force_recompute(bool val)
>  {
> @@ -282,6 +286,7 @@ engine_recompute(struct engine_node *node, bool forced, 
> bool allowed)
>  
>      if (!allowed) {
>          VLOG_DBG("node: %s, recompute aborted", node->name);
> +        COVERAGE_INC(engine_abort);
>          engine_set_node_state(node, EN_ABORTED);
>          return;
>      }
> diff --git a/lib/inc-proc-eng.h b/lib/inc-proc-eng.h
> index 857234677..6067a88c1 100644
> --- a/lib/inc-proc-eng.h
> +++ b/lib/inc-proc-eng.h
> @@ -247,6 +247,10 @@ void *engine_get_internal_data(struct engine_node *node);
>  #define engine_set_node_state(node, state) \
>      engine_set_node_state_at(node, state, OVS_SOURCE_LOCATOR)
>  
> +#define engine_set_node_updated(node, NAME) \
> +    engine_set_node_state(node, EN_UPDATED); \
> +    ENGINE_RUN_COVERAGE_INC(NAME);
> +
>  struct ed_ovsdb_index {
>      const char *name;
>      struct ovsdb_idl_index *index;
> @@ -311,7 +315,7 @@ en_##DB_NAME##_##TBL_NAME##_run(struct engine_node *node, 
> \
>      const struct DB_NAME##rec_##TBL_NAME##_table *table = \
>          EN_OVSDB_GET(node); \
>      if (DB_NAME##rec_##TBL_NAME##_table_track_get_first(table)) { \
> -        engine_set_node_state(node, EN_UPDATED); \
> +        engine_set_node_updated(node, DB_NAME##_##TBL_NAME); \
>          return; \
>      } \
>      engine_set_node_state(node, EN_UNCHANGED); \
> @@ -352,4 +356,10 @@ static void en_##DB_NAME##_##TBL_NAME##_cleanup(void 
> *data OVS_UNUSED) \
>  #define ENGINE_NODE_OVS(TBL_NAME, TBL_NAME_STR) \
>      ENGINE_NODE_OVSDB(ovs, "OVS", TBL_NAME, TBL_NAME_STR);
>  
> +#define ENGINE_RUN_COVERAGE_DEFINE(NAME)    \
> +    COVERAGE_DEFINE(en_##NAME##_run);
> +
> +#define ENGINE_RUN_COVERAGE_INC(NAME)       \
> +    COVERAGE_INC(en_##NAME##_run);
> +
>  #endif /* lib/inc-proc-eng.h */
> 

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