On 9/22/21 5:25 PM, Michael Santana wrote:
>
>
> On 9/22/21 3:24 AM, Dumitru Ceara wrote:
>> On 9/21/21 6:12 PM, Michael Santana wrote:
>>>
>>>
>>> On 9/16/21 11:37 AM, 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.
>>> Very well written and explained
>>>
>>> Everything looks good to me. I just have one small question down below
>>
>> Thanks for reviewing this!
>>
>>>>
>>>> V2:
>>>> - rebased (fixed conflicts in NEWS).
>>>> ---
>>>> 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);
>>>> +
>>>> + if (!txn_row->table->log) {
>>>> + return;
>>>> + }
>>> Shouldn't this if-block be before the rate limitter initialization?
>>
>> Well, I don't think it really matters because rl_insert/update/delete
>> are static variables but if you think it's more readable I can send a v2
>> with the if-block moved up at the beginning of the function.
> I missed it being static variables and the rate limiter functions being
> preprocessor functions. I was concern about hurting performance in the
> default case by making function calls that wouldn't be used and then
> immediately returning.
>
> Despite that I think we can still hurt performance (maybe insignificant
> amount?) by calling ovsdb_txn_row_log() every time from
> ovsdb_txn_row_commit()
>
> maybe checking if it's enabled before calling ovsdb_txn_row_log()
> prevent us from making unnecessary function calls in the default case
> where the log is disabled:
> if (txn_row->table->log) {
> ovsdb_txn_row_log(txn_row);
> }
ovsdb_txn_row_log() is static and will most likely be inlined by the
compiler. So I don't think it matters either if we add the if before
the call or not.
>
> I dont how much of a difference it makes in terms of performance. If
> it's insignificant then just ignore this comment
>
Just to make sure, I checked, on my rhel machine with quite an old GCC
version (gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-44)), when compiling
with -O2:
$ objdump -S ovsdb/ovsdb-server
0000000000417a30 <ovsdb_txn_row_commit>:
{
[...]
if (!txn_row->table->log) {
417ac4: 48 8b 45 38 mov 0x38(%rbp),%rax
417ac8: 80 78 38 00 cmpb $0x0,0x38(%rax)
417acc: 0f 85 bf 00 00 00 jne 417b91
<ovsdb_txn_row_commit+0x161>
417ad2: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1)
ovsdb_txn_row_prefree(txn_row);
417ad8: 48 89 ef mov %rbp,%rdi
417adb: e8 70 f7 ff ff callq 417250
<ovsdb_txn_row_prefree>
So I guess it's OK as is.
Regards,
Dumitru
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