On 9/23/21 11:47 AM, Mark Gray wrote:
> On 16/09/2021 16:37, Dumitru Ceara wrote:
>> Add a new command, 'ovsdb-server/log-db-ops DB TABLE on|off', which
>> allows the user to enable/disable transaction logging for specific
>> databases and tables.
>>
>> By default, logging is disabled. Once enabled, logs are generated
>> with level INFO and are also rate limited.
>>
>> If used with care, this command can be useful in analyzing production
>> deployment performance issues, allowing the user to pin point
>> bottlenecks without the need to enable wider debug logs, e.g., jsonrpc.
>>
>> Signed-off-by: Dumitru Ceara <[email protected]>
>> ---
>> A sample use case is an ovn-kubernetes scaled deployment in which
>> we're interesting in reducing time to bring up PODs (represented by
>> OVN logical switch ports). In order to determine exactly where the
>> bottleneck is when provisioning PODs (CMS/ovn-nbctl/client
>> IDLs/ovsdb-server/ovn-controller/etc) we need timestamps of when
>> operations happen at various places in the stack.
>>
>> Without this patch the only option for tracking when transactions
>> happen in the Northbound database is to enable jsonrpc debug logs in
>> ovsdb-server. This generates a rather large amount of data.
>>
>> Instead, now, users would be able to just enable logging for the
>> Logical_Switch_Port table getting more relevant and precise
>> information.
>>
>> V2:
>> - rebased (fixed conflicts in NEWS).
>
> Generally ok and I also did a quick test but I have a few comments on
> the UI which wouldn't block an ACK and one small comment below in the code:
Thanks for the review!
>
> * My personal preference would be that the syntax somewhat followed the
> vlog/set one that seperates terms by ':'. Also a more memorable name.
> For example tlog/set DB:TABLE:on or something like that but feel free to
> choose to completely ignore me :) I just find it can sometimes be
> difficult to remember syntax so I prefer some consistency.
Makes sense, I'll try to come up with something more consistent.
>
> * One limititation is that I don't think we can add a log before a table
> is created (i.e. to see the first entry). For example, let's say I want
> to log the very first creation of a bridge using `ovs-vsctl add-br br0`.
> Is there any way around it? I couldn't think of one.
I'm not sure I follow this point. If you enable logging for the Bridge
table before adding the first bridge you'll get the log, e.g., in an OVS
sandbox:
$ ovs-appctl -t $PWD/sandbox/ovsdb-server.*.ctl ovsdb-server/log-db-ops
Open_vSwitch Bridge on
$ ovs-vsctl show
f43b960d-13f9-48d1-9898-703a3ac3f730
$ ovs-vsctl add-br br9
$ grep transaction sandbox/ovsdb-server.log
2021-09-23T09:57:53.426Z|00007|transaction|INFO|table:Bridge,op:inserted,name:br9,flood_vlans:[],auto_attach:[],ports:[388811ab-13a9-4b50-92c6-10c00a8b5e42],stp_enable:false,rstp_enable:false,_uuid:8a59955c-2a3c-41d3-9e93-66845e51878b,fail_mode:[],rstp_status:{},flow_tables:{},_version:1603df48-3730-4324-a71b-1c9f7eadb865,netflow:[],datapath_type:"",controller:[],other_config:{},external_ids:{},status:{},ipfix:[],datapath_id:[],mirrors:[],mcast_snooping_enable:false,datapath_version:"",sflow:[],protocols:[]
[...]
>
> * Could you make the table and database names case-insensitive. For
> example, I can do `ovs-vsctl list open` even though the table name is
> actually Open_vSwitch? However, with this I need to specify the actual
> table name.
>
We can try but this would be a bit of an orthogonal change. For example
"ovs-appctl -t .. ovsdb-server/remove-db DB" only accepts case sensitive
database names (due to case sensitive shash operations). For using
partial table names and/or, it would also be a more complex change.
What you mentioned (ovs-vsctl) is actually implemented on the client
side in db-ctl-base.c, get_table()/score_partial_match().
> * There is no way to list the tables that are currently 'on'. Something
> like vlog/list.
Good idea, I'll add it!
>
> * Would it be useful to be able to specify which level to log to?: e.g.
>
> tlog/set DB:TABLE:info
>
I'm not sure, maybe, although my initial goal was to make this usable at
a reasonably high log level, e.g., INFO. I don't think there's a point
to use an even higher level though (like WARN/ERR), though.
> * Would it be useful to have a non-verbose mode that only states that an
> insert/delete/update happened?
>
Would you log some row specific information then? E.g., _uuid.
>> ---
>> NEWS | 4 ++++
>> ovsdb/ovsdb-server.c | 38 +++++++++++++++++++++++++++++++++
>> ovsdb/row.c | 17 +++++++++++++++
>> ovsdb/row.h | 1 +
>> ovsdb/table.c | 7 ++++++
>> ovsdb/table.h | 3 +++
>> ovsdb/transaction.c | 51 ++++++++++++++++++++++++++++++++++++++++++++
>> 7 files changed, 121 insertions(+)
>>
>> diff --git a/NEWS b/NEWS
>> index 90f4b15902b8..d56329772276 100644
>> --- a/NEWS
>> +++ b/NEWS
>> @@ -10,6 +10,10 @@ Post-v2.16.0
>> limiting behavior.
>> * Add hardware offload support for matching IPv4/IPv6 frag types
>> (experimental).
>> + - OVSDB:
>> + * New unixctl command 'ovsdb-server/log-db-ops DB TABLE on|off".
>> + If turned on, ovsdb-server will log (at level INFO and rate limited)
>> + all operations that are committed to table TABLE in the DB database.
>>
>>
>> v2.16.0 - 16 Aug 2021
>> diff --git a/ovsdb/ovsdb-server.c b/ovsdb/ovsdb-server.c
>> index 0b3d2bb71432..c48645f7e255 100644
>> --- a/ovsdb/ovsdb-server.c
>> +++ b/ovsdb/ovsdb-server.c
>> @@ -115,6 +115,7 @@ static unixctl_cb_func ovsdb_server_list_remotes;
>> static unixctl_cb_func ovsdb_server_add_database;
>> static unixctl_cb_func ovsdb_server_remove_database;
>> static unixctl_cb_func ovsdb_server_list_databases;
>> +static unixctl_cb_func ovsdb_server_log_db_ops;
>>
>> static void read_db(struct server_config *, struct db *);
>> static struct ovsdb_error *open_db(struct server_config *,
>> @@ -443,6 +444,8 @@ main(int argc, char *argv[])
>> ovsdb_server_remove_database, &server_config);
>> unixctl_command_register("ovsdb-server/list-dbs", "", 0, 0,
>> ovsdb_server_list_databases, &all_dbs);
>> + unixctl_command_register("ovsdb-server/log-db-ops", "DB TABLE on|off",
>> + 3, 3, ovsdb_server_log_db_ops, &all_dbs);
>> unixctl_command_register("ovsdb-server/perf-counters-show", "", 0, 0,
>> ovsdb_server_perf_counters_show, NULL);
>> unixctl_command_register("ovsdb-server/perf-counters-clear", "", 0, 0,
>> @@ -1769,6 +1772,41 @@ ovsdb_server_list_databases(struct unixctl_conn
>> *conn, int argc OVS_UNUSED,
>> ds_destroy(&s);
>> }
>>
>> +static void
>> +ovsdb_server_log_db_ops(struct unixctl_conn *conn, int argc OVS_UNUSED,
>> + const char *argv[], void *all_dbs_)
>> +{
>> + struct shash *all_dbs = all_dbs_;
>> + const char *db_name = argv[1];
>> + const char *tbl_name = argv[2];
>> + const char *command = argv[3];
>> + bool log;
>> +
>> + if (!strcmp(command, "on")) {
>> + log = true;
>> + } else if (!strcmp(command, "off")) {
>> + log = false;
>> + } else {
>> + unixctl_command_reply_error(conn, "invalid argument");
>> + return;
>> + }
>> +
>> + struct db *db = shash_find_data(all_dbs, db_name);
>> + if (!db) {
>> + unixctl_command_reply_error(conn, "no such database");
>> + return;
>> + }
>> +
>> + struct ovsdb_table *table = ovsdb_get_table(db->db, tbl_name);
>> + if (!table) {
>> + unixctl_command_reply_error(conn, "no such table");
>> + return;
>> + }
>> +
>> + ovsdb_table_log_ops(table, log);
>> + unixctl_command_reply(conn, NULL);
>> +}
>> +
>> static void
>> ovsdb_server_get_sync_status(struct unixctl_conn *conn, int argc OVS_UNUSED,
>> const char *argv[] OVS_UNUSED, void *config_)
>> diff --git a/ovsdb/row.c b/ovsdb/row.c
>> index 65a0546211c8..5e31716506bc 100644
>> --- a/ovsdb/row.c
>> +++ b/ovsdb/row.c
>> @@ -278,6 +278,23 @@ ovsdb_row_to_json(const struct ovsdb_row *row,
>> }
>> return json;
>> }
>> +
>> +void
>> +ovsdb_row_to_string(const struct ovsdb_row *row, struct ds *out)
>> +{
>> + struct shash_node *node;
>> +
>> + SHASH_FOR_EACH (node, &row->table->schema->columns) {
>> + const struct ovsdb_column *column = node->data;
>> +
>> + ds_put_format(out, "%s:", column->name);
>> + ovsdb_datum_to_string(&row->fields[column->index], &column->type,
>> out);
>> + ds_put_cstr(out, ",");
>> + }
>> + if (shash_count(&row->table->schema->columns)) {
>> + ds_chomp(out, ',');
>> + }
>> +}
>>
>> void
>> ovsdb_row_set_init(struct ovsdb_row_set *set)
>> diff --git a/ovsdb/row.h b/ovsdb/row.h
>> index 394ac8eb49b6..f22a08ecd197 100644
>> --- a/ovsdb/row.h
>> +++ b/ovsdb/row.h
>> @@ -95,6 +95,7 @@ struct ovsdb_error *ovsdb_row_from_json(struct ovsdb_row *,
>> OVS_WARN_UNUSED_RESULT;
>> struct json *ovsdb_row_to_json(const struct ovsdb_row *,
>> const struct ovsdb_column_set *include);
>> +void ovsdb_row_to_string(const struct ovsdb_row *, struct ds *);
>>
>> static inline const struct uuid *
>> ovsdb_row_get_uuid(const struct ovsdb_row *row)
>> diff --git a/ovsdb/table.c b/ovsdb/table.c
>> index 455a3663fe89..b7b41d139914 100644
>> --- a/ovsdb/table.c
>> +++ b/ovsdb/table.c
>> @@ -301,10 +301,17 @@ ovsdb_table_create(struct ovsdb_table_schema *ts)
>> hmap_init(&table->indexes[i]);
>> }
>> hmap_init(&table->rows);
>> + table->log = false;
>>
>> return table;
>> }
>>
>> +void
>> +ovsdb_table_log_ops(struct ovsdb_table *table, bool enabled)
>> +{
>> + table->log = enabled;
>> +}
>> +
>> void
>> ovsdb_table_destroy(struct ovsdb_table *table)
>> {
>> diff --git a/ovsdb/table.h b/ovsdb/table.h
>> index ce69a5d130bf..be88b7a59279 100644
>> --- a/ovsdb/table.h
>> +++ b/ovsdb/table.h
>> @@ -63,10 +63,13 @@ struct ovsdb_table {
>> * ovsdb_row"s. Each of the hmap_nodes in indexes[i] are at index 'i'
>> at
>> * the end of struct ovsdb_row, following the 'fields' member. */
>> struct hmap *indexes;
>> +
>> + bool log; /* True if logging is enabled for this table. */
>> };
>>
>> struct ovsdb_table *ovsdb_table_create(struct ovsdb_table_schema *);
>> void ovsdb_table_destroy(struct ovsdb_table *);
>> +void ovsdb_table_log_ops(struct ovsdb_table *, bool);
>>
>> const struct ovsdb_row *ovsdb_table_get_row(const struct ovsdb_table *,
>> const struct uuid *);
>> diff --git a/ovsdb/transaction.c b/ovsdb/transaction.c
>> index 8ffefcf7c9d0..dc07e9c00a4b 100644
>> --- a/ovsdb/transaction.c
>> +++ b/ovsdb/transaction.c
>> @@ -29,6 +29,7 @@
>> #include "openvswitch/vlog.h"
>> #include "ovsdb-error.h"
>> #include "ovsdb.h"
>> +#include "ovs-thread.h"
>> #include "row.h"
>> #include "storage.h"
>> #include "table.h"
>> @@ -95,6 +96,7 @@ struct ovsdb_txn_row {
>> static struct ovsdb_error * OVS_WARN_UNUSED_RESULT
>> delete_garbage_row(struct ovsdb_txn *txn, struct ovsdb_txn_row *r);
>> static void ovsdb_txn_row_prefree(struct ovsdb_txn_row *);
>> +static void ovsdb_txn_row_log(const struct ovsdb_txn_row *);
>> static struct ovsdb_error * OVS_WARN_UNUSED_RESULT
>> for_each_txn_row(struct ovsdb_txn *txn,
>> struct ovsdb_error *(*)(struct ovsdb_txn *,
>> @@ -104,6 +106,11 @@ for_each_txn_row(struct ovsdb_txn *txn,
>> * processed. */
>> static unsigned int serial;
>>
>> +/* Used by ovsdb_txn_row_log() to avoid reallocating dynamic strings
>> + * every time a row operation is logged.
>> + */
>> +DEFINE_STATIC_PER_THREAD_DATA(struct ds, row_log_str, DS_EMPTY_INITIALIZER);
>> +
>> struct ovsdb_txn *
>> ovsdb_txn_create(struct ovsdb *db)
>> {
>> @@ -422,6 +429,49 @@ update_ref_counts(struct ovsdb_txn *txn)
>> return for_each_txn_row(txn, check_ref_count);
>> }
>>
>> +static void
>> +ovsdb_txn_row_log(const struct ovsdb_txn_row *txn_row)
>> +{
>> + static struct vlog_rate_limit rl_insert = VLOG_RATE_LIMIT_INIT(30, 60);
>> + static struct vlog_rate_limit rl_update = VLOG_RATE_LIMIT_INIT(30, 60);
>> + static struct vlog_rate_limit rl_delete = VLOG_RATE_LIMIT_INIT(30, 60);
>
> Why do you have 3 different rate limiters?
>
Updates usually happen more often than inserts/deletes (e.g., with OVN
logical ports). I thought it would be more useful if updates didn't
consume tokens from the insert/delete logs. But thinking more about it,
a rate of 30 logs per minute with a burst of 60 doesn't allow too many
transactions to be logged often either. So, I guess, in a real use case
the user would disable rate limiting for the "transaction" vlog module.
We might as well move to a single rate limiter then.
I'll change it in the next revision.
>> +
>> + if (!txn_row->table->log) {
>> + return;
>> + }
>> +
>> + size_t n_columns = shash_count(&txn_row->table->schema->columns);
>> + struct ovsdb_row *log_row;
>> + const char *op = NULL;
>> +
>> + if (!txn_row->old && txn_row->new) {
>> + if (!vlog_should_drop(&this_module, VLL_INFO, &rl_insert)) {
>> + log_row = txn_row->new;
>> + op = "inserted";
>> + }
>> + } else if (txn_row->old && txn_row->new
>> + && !bitmap_is_all_zeros(txn_row->changed, n_columns)) {
>> + if (!vlog_should_drop(&this_module, VLL_INFO, &rl_update)) {
>> + log_row = txn_row->new;
>> + op = "updated";
>> + }
>> + } else if (txn_row->old && !txn_row->new) {
>> + if (!vlog_should_drop(&this_module, VLL_INFO, &rl_delete)) {
>> + log_row = txn_row->old;
>> + op = "deleted";
>> + }
>> + }
>> +
>> + if (op) {
>> + struct ds *ds = row_log_str_get();
>> + ds_clear(ds);
>> + ds_put_format(ds, "table:%s,op:%s,", txn_row->table->schema->name,
>> + op);
>> + ovsdb_row_to_string(log_row, ds);
>> + VLOG_INFO("%s", ds_cstr(ds));
>> + }
>> +}
>> +
>> static struct ovsdb_error *
>> ovsdb_txn_row_commit(struct ovsdb_txn *txn OVS_UNUSED,
>> struct ovsdb_txn_row *txn_row)
>> @@ -445,6 +495,7 @@ ovsdb_txn_row_commit(struct ovsdb_txn *txn OVS_UNUSED,
>> }
>> }
>>
>> + ovsdb_txn_row_log(txn_row);
>> ovsdb_txn_row_prefree(txn_row);
>> if (txn_row->new) {
>> txn_row->new->n_refs = txn_row->n_refs;
>>
>
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