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:
* 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.
* 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.
* 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.
* There is no way to list the tables that are currently 'on'. Something
like vlog/list.
* Would it be useful to be able to specify which level to log to?: e.g.
tlog/set DB:TABLE:info
* Would it be useful to have a non-verbose mode that only states that an
insert/delete/update happened?
> ---
> 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?
> +
> + 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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