Implement latency tracking, internal event log and watchdog

conf/conf.h

@@ -41,6 +41,10 @@ struct config {
   u32 gr_wait;				/* Graceful restart wait timeout */
 
   int cli_debug;			/* Tracing of CLI connections and commands */
+  int latency_debug;			/* I/O loop tracks duration of each event */
+  u32 latency_limit;			/* Events with longer duration are logged (us) */
+  u32 watchdog_warning;			/* I/O loop watchdog limit for warning (us) */
+  u32 watchdog_timeout;			/* Watchdog timeout (in seconds, 0 = disabled) */
   char *err_msg;			/* Parser error message */
   int err_lino;				/* Line containing error */
   char *err_file_name;			/* File name containing error */

doc/bird.conf.example

@@ -33,6 +33,10 @@
 # Turn on global debugging of all protocols
 #debug protocols all;
 
+# Turn on internal watchdog
+#watchdog warning 5 s;
+#watchdog timeout 30 s;
+
 # The direct protocol automatically generates device routes to
 # all network interfaces. Can exist in as many instances as you wish
 # if you want to populate multiple routing tables with device routes.

doc/bird.sgml

@@ -344,6 +344,23 @@ protocol rip {
 	of connects and disconnects, 2 and higher for logging of all client
 	commands). Default: 0.
 
+	<tag>debug latency <m/switch/</tag>
+	Activate tracking of elapsed time for internal events. Recent events
+	could be examined using <cf/dump events/ command. Default: off.
+
+	<tag>debug latency limit <m/time/</tag>
+	If <cf/debug latency/ is enabled, this option allows to specify a limit
+	for elapsed time. Events exceeding the limit are logged. Default: 1 s.
+
+	<tag>watchdog warning <m/time/</tag>
+	Set time limit for I/O loop cycle. If one iteration took more time to
+	complete, a warning is logged. Default: 5 s.
+
+	<tag>watchdog timeout <m/time/</tag>
+	Set time limit for I/O loop cycle. If the limit is breached, BIRD is
+	killed by abort signal. The timeout has effective granularity of
+	seconds, zero means disabled. Default: disabled (0).
+
 	<tag>mrtdump "<m/filename/"</tag>
 	Set MRTdump file name. This option must be specified to allow MRTdump
 	feature. Default: no dump file.

lib/event.c

@@ -114,6 +114,8 @@ ev_schedule(event *e)
   ev_enqueue(&global_event_list, e);
 }
 
+void io_log_event(void *hook, void *data);
+
 /**
  * ev_run_list - run an event list
  * @l: an event list
@@ -132,6 +134,11 @@ ev_run_list(event_list *l)
   WALK_LIST_FIRST(n, tmp_list)
     {
       event *e = SKIP_BACK(event, n, n);
+
+      /* This is ugly hack, we want to log just events executed from the main I/O loop */
+      if (l == &global_event_list)
+	io_log_event(e->hook, e->data);
+
       ev_run(e);
     }
   return !EMPTY_LIST(*l);

nest/config.Y

@@ -621,6 +621,8 @@ CF_CLI(DUMP RESOURCES,,, [[Dump all allocated resource]])
 { rdump(&root_pool); cli_msg(0, ""); } ;
 CF_CLI(DUMP SOCKETS,,, [[Dump open sockets]])
 { sk_dump_all(); cli_msg(0, ""); } ;
+CF_CLI(DUMP EVENTS,,, [[Dump event log]])
+{ io_log_dump(); cli_msg(0, ""); } ;
 CF_CLI(DUMP INTERFACES,,, [[Dump interface information]])
 { if_dump_all(); cli_msg(0, ""); } ;
 CF_CLI(DUMP NEIGHBORS,,, [[Dump neighbor cache]])

sysdep/unix/config.Y

@@ -15,6 +15,7 @@ CF_DECLS
 
 CF_KEYWORDS(LOG, SYSLOG, ALL, DEBUG, TRACE, INFO, REMOTE, WARNING, ERROR, AUTH, FATAL, BUG, STDERR, SOFT)
 CF_KEYWORDS(TIMEFORMAT, ISO, OLD, SHORT, LONG, BASE, NAME, CONFIRM, UNDO, CHECK, TIMEOUT)
+CF_KEYWORDS(DEBUG, LATENCY, LIMIT, WATCHDOG, WARNING, TIMEOUT)
 
 %type <i> log_mask log_mask_list log_cat cfg_timeout
 %type <g> log_file
@@ -83,6 +84,7 @@ mrtdump_base:
    }
  ;
 
+
 CF_ADDTO(conf, timeformat_base)
 
 timeformat_which:
@@ -104,6 +106,17 @@ timeformat_base:
    TIMEFORMAT timeformat_spec ';'
  ;
 
+
+CF_ADDTO(conf, debug_unix)
+
+debug_unix:
+   DEBUG LATENCY bool { new_config->latency_debug = $3; }
+ | DEBUG LATENCY LIMIT expr_us { new_config->latency_limit = $4; }
+ | WATCHDOG WARNING expr_us { new_config->watchdog_warning = $3; }
+ | WATCHDOG TIMEOUT expr_us { new_config->watchdog_timeout = ($3 + 999999) TO_S; }
+ ;
+
+
 /* Unix specific commands */
 
 CF_CLI_HELP(CONFIGURE, ..., [[Reload configuration]])

sysdep/unix/io.c

@@ -332,6 +332,8 @@ tm_first_shot(void)
   return x;
 }
 
+void io_log_event(void *hook, void *data);
+
 static void
 tm_shot(void)
 {
@@ -372,6 +374,7 @@ tm_shot(void)
 	    i = 0;
 	  tm_start(t, i);
 	}
+      io_log_event(t->hook, t->data);
       t->hook(t);
     }
 }
@@ -1839,6 +1842,162 @@ sk_dump_all(void)
 }
 
 
+/*
+ *	Internal event log and watchdog
+ */
+
+#define EVENT_LOG_LENGTH 32
+
+struct event_log_entry
+{
+  void *hook;
+  void *data;
+  btime timestamp;
+  btime duration;
+};
+
+static struct event_log_entry event_log[EVENT_LOG_LENGTH];
+static struct event_log_entry *event_open;
+static int event_log_pos, event_log_num, watchdog_active;
+static btime last_time;
+static btime loop_time;
+
+static void
+io_update_time(void)
+{
+  struct timespec ts;
+  int rv;
+
+  if (!clock_monotonic_available)
+    return;
+
+  /*
+   * This is third time-tracking procedure (after update_times() above and
+   * times_update() in BFD), dedicated to internal event log and latency
+   * tracking. Hopefully, we consolidate these sometimes.
+   */
+
+  rv = clock_gettime(CLOCK_MONOTONIC, &ts);
+  if (rv < 0)
+    die("clock_gettime: %m");
+
+  last_time = ((s64) ts.tv_sec S) + (ts.tv_nsec / 1000);
+
+  if (event_open)
+  {
+    event_open->duration = last_time - event_open->timestamp;
+
+    if (event_open->duration > config->latency_limit)
+      log(L_WARN "Event 0x%p 0x%p took %d ms",
+	  event_open->hook, event_open->data, (int) (event_open->duration TO_MS));
+
+    event_open = NULL;
+  }
+}
+
+/**
+ * io_log_event - mark approaching event into event log
+ * @hook: event hook address
+ * @data: event data address
+ *
+ * Store info (hook, data, timestamp) about the following internal event into
+ * a circular event log (@event_log). When latency tracking is enabled, the log
+ * entry is kept open (in @event_open) so the duration can be filled later.
+ */
+void
+io_log_event(void *hook, void *data)
+{
+  if (config->latency_debug)
+    io_update_time();
+
+  struct event_log_entry *en = event_log + event_log_pos;
+
+  en->hook = hook;
+  en->data = data;
+  en->timestamp = last_time;
+  en->duration = 0;
+
+  event_log_num++;
+  event_log_pos++;
+  event_log_pos %= EVENT_LOG_LENGTH;
+
+  event_open = config->latency_debug ? en : NULL;
+}
+
+static inline void
+io_close_event(void)
+{
+  if (event_open)
+    io_update_time();
+}
+
+void
+io_log_dump(void)
+{
+  int i;
+
+  log(L_DEBUG "Event log:");
+  for (i = 0; i < EVENT_LOG_LENGTH; i++)
+  {
+    struct event_log_entry *en = event_log + (event_log_pos + i) % EVENT_LOG_LENGTH;
+    if (en->hook)
+      log(L_DEBUG "  Event 0x%p 0x%p at %8d for %d ms", en->hook, en->data,
+	  (int) ((last_time - en->timestamp) TO_MS), (int) (en->duration TO_MS));
+  }
+}
+
+void
+watchdog_sigalrm(int sig UNUSED)
+{
+  /* Update last_time and duration, but skip latency check */
+  config->latency_limit = 0xffffffff;
+  io_update_time();
+
+  /* We want core dump */
+  abort();
+}
+
+static inline void
+watchdog_start1(void)
+{
+  io_update_time();
+
+  loop_time = last_time;
+}
+
+static inline void
+watchdog_start(void)
+{
+  io_update_time();
+
+  loop_time = last_time;
+  event_log_num = 0;
+
+  if (config->watchdog_timeout)
+  {
+    alarm(config->watchdog_timeout);
+    watchdog_active = 1;
+  }
+}
+
+static inline void
+watchdog_stop(void)
+{
+  io_update_time();
+
+  if (watchdog_active)
+  {
+    alarm(0);
+    watchdog_active = 0;
+  }
+
+  btime duration = last_time - loop_time;
+  if (duration > config->watchdog_warning)
+    log(L_WARN "I/O loop cycle took %d ms for %d events",
+	(int) (duration TO_MS), event_log_num);
+}
+
+
 /*
  *	Main I/O Loop
  */
@@ -1873,6 +2032,7 @@ io_loop(void)
   sock *s;
   node *n;
 
+  watchdog_start1();
   sock_recalc_fdsets_p = 1;
   for(;;)
     {
@@ -1887,6 +2047,8 @@ io_loop(void)
       timo.tv_sec = events ? 0 : MIN(tout - now, 3);
       timo.tv_usec = 0;
 
+      io_close_event();
+
       if (sock_recalc_fdsets_p)
 	{
 	  sock_recalc_fdsets_p = 0;
@@ -1923,25 +2085,30 @@ io_loop(void)
 
       if (async_config_flag)
 	{
+	  io_log_event(async_config, NULL);
 	  async_config();
 	  async_config_flag = 0;
 	  continue;
 	}
       if (async_dump_flag)
 	{
+	  io_log_event(async_dump, NULL);
 	  async_dump();
 	  async_dump_flag = 0;
 	  continue;
 	}
       if (async_shutdown_flag)
 	{
+	  io_log_event(async_shutdown, NULL);
 	  async_shutdown();
 	  async_shutdown_flag = 0;
 	  continue;
 	}
 
       /* And finally enter select() to find active sockets */
+      watchdog_stop();
       hi = select(hi+1, &rd, &wr, NULL, &timo);
+      watchdog_start();
 
       if (hi < 0)
 	{
@@ -1965,6 +2132,7 @@ io_loop(void)
 		do
 		  {
 		    steps--;
+		    io_log_event(s->rx_hook, s->data);
 		    e = sk_read(s);
 		    if (s != current_sock)
 		      goto next;
@@ -1976,6 +2144,7 @@ io_loop(void)
 		do
 		  {
 		    steps--;
+		    io_log_event(s->tx_hook, s->data);
 		    e = sk_write(s);
 		    if (s != current_sock)
 		      goto next;
@@ -2003,6 +2172,7 @@ io_loop(void)
 	      if ((s->type < SK_MAGIC) && FD_ISSET(s->fd, &rd) && s->rx_hook)
 		{
 		  count++;
+		  io_log_event(s->rx_hook, s->data);
 		  e = sk_read(s);
 		  if (s != current_sock)
 		      goto next2;

sysdep/unix/main.c

@@ -168,6 +168,9 @@ sysdep_preconfig(struct config *c)
 {
   init_list(&c->logfiles);
 
+  c->latency_limit = UNIX_DEFAULT_LATENCY_LIMIT;
+  c->watchdog_warning = UNIX_DEFAULT_WATCHDOG_WARNING;
+
 #ifdef PATH_IPROUTE_DIR
   read_iproute_table(PATH_IPROUTE_DIR "/rt_protos", "ipp_", 256);
   read_iproute_table(PATH_IPROUTE_DIR "/rt_realms", "ipr_", 256);
@@ -585,6 +588,8 @@ handle_sigterm(int sig UNUSED)
   async_shutdown_flag = 1;
 }
 
+void watchdog_sigalrm(int sig UNUSED);
+
 static void
 signal_init(void)
 {
@@ -600,6 +605,9 @@ signal_init(void)
   sa.sa_handler = handle_sigterm;
   sa.sa_flags = SA_RESTART;
   sigaction(SIGTERM, &sa, NULL);
+  sa.sa_handler = watchdog_sigalrm;
+  sa.sa_flags = 0;
+  sigaction(SIGALRM, &sa, NULL);
   signal(SIGPIPE, SIG_IGN);
 }
 

sysdep/unix/unix.h

@@ -29,6 +29,8 @@ void cmd_shutdown(void);
 
 #define UNIX_DEFAULT_CONFIGURE_TIMEOUT	300
 
+#define UNIX_DEFAULT_LATENCY_LIMIT	(1 S_)
+#define UNIX_DEFAULT_WATCHDOG_WARNING	(5 S_)
 
 /* io.c */
 
@@ -99,6 +101,7 @@ volatile int async_shutdown_flag;
 
 void io_init(void);
 void io_loop(void);
+void io_log_dump(void);
 int sk_open_unix(struct birdsock *s, char *name);
 void *tracked_fopen(struct pool *, char *name, char *mode);
 void test_old_bird(char *path);