Clean up multi-thread barrier-sync hold-down timer
[vpp.git] / src / vlib / threads.c
index ed1ba61..52886df 100644 (file)
@@ -719,8 +719,6 @@ start_workers (vlib_main_t * vm)
       for (i = 0; i < vec_len (tm->registrations); i++)
        {
          vlib_node_main_t *nm, *nm_clone;
-         vlib_buffer_free_list_t *fl_clone, *fl_orig;
-         vlib_buffer_free_list_t *orig_freelist_pool;
          int k;
 
          tr = tm->registrations[i];
@@ -868,9 +866,11 @@ start_workers (vlib_main_t * vm)
              nm_clone->processes = vec_dup_aligned (nm->processes,
                                                     CLIB_CACHE_LINE_BYTES);
 
-             /* zap the (per worker) frame freelists, etc */
-             nm_clone->frame_sizes = 0;
+             /* Create per-thread frame freelist */
+             nm_clone->frame_sizes = vec_new (vlib_frame_size_t, 1);
+#ifdef VLIB_SUPPORTS_ARBITRARY_SCALAR_SIZES
              nm_clone->frame_size_hash = hash_create (0, sizeof (uword));
+#endif
 
              /* Packet trace buffers are guaranteed to be empty, nothing to do here */
 
@@ -883,26 +883,6 @@ start_workers (vlib_main_t * vm)
                (vlib_mains[0]->error_main.counters_last_clear,
                 CLIB_CACHE_LINE_BYTES);
 
-             /* Fork the vlib_buffer_main_t free lists, etc. */
-             orig_freelist_pool = vm_clone->buffer_free_list_pool;
-             vm_clone->buffer_free_list_pool = 0;
-
-            /* *INDENT-OFF* */
-            pool_foreach (fl_orig, orig_freelist_pool,
-                          ({
-                            pool_get_aligned (vm_clone->buffer_free_list_pool,
-                                              fl_clone, CLIB_CACHE_LINE_BYTES);
-                            ASSERT (fl_orig - orig_freelist_pool
-                                    == fl_clone - vm_clone->buffer_free_list_pool);
-
-                            fl_clone[0] = fl_orig[0];
-                            fl_clone->buffers = 0;
-                            vec_validate(fl_clone->buffers, 0);
-                            vec_reset_length(fl_clone->buffers);
-                            fl_clone->n_alloc = 0;
-                          }));
-/* *INDENT-ON* */
-
              worker_thread_index++;
            }
        }
@@ -1402,20 +1382,23 @@ vlib_worker_thread_fork_fixup (vlib_fork_fixup_t which)
 #endif
 
 void
-vlib_worker_thread_barrier_sync_int (vlib_main_t * vm)
+vlib_worker_thread_barrier_sync_int (vlib_main_t * vm, const char *func_name)
 {
   f64 deadline;
   f64 now;
   f64 t_entry;
   f64 t_open;
   f64 t_closed;
+  f64 max_vector_rate;
   u32 count;
+  int i;
 
   if (vec_len (vlib_mains) < 2)
     return;
 
   ASSERT (vlib_get_thread_index () == 0);
 
+  vlib_worker_threads[0].barrier_caller = func_name;
   count = vec_len (vlib_mains) - 1;
 
   /* Record entry relative to last close */
@@ -1429,23 +1412,41 @@ vlib_worker_thread_barrier_sync_int (vlib_main_t * vm)
       return;
     }
 
+  /*
+   * Need data to decide if we're working hard enough to honor
+   * the barrier hold-down timer.
+   */
+  max_vector_rate = 0.0;
+  for (i = 1; i < vec_len (vlib_mains); i++)
+    max_vector_rate =
+      clib_max (max_vector_rate,
+               vlib_last_vectors_per_main_loop_as_f64 (vlib_mains[i]));
+
   vlib_worker_threads[0].barrier_sync_count++;
 
   /* Enforce minimum barrier open time to minimize packet loss */
   ASSERT (vm->barrier_no_close_before <= (now + BARRIER_MINIMUM_OPEN_LIMIT));
 
-  while (1)
+  /*
+   * If any worker thread seems busy, which we define
+   * as a vector rate above 10, we enforce the barrier hold-down timer
+   */
+  if (max_vector_rate > 10.0)
     {
-      now = vlib_time_now (vm);
-      /* Barrier hold-down timer expired? */
-      if (now >= vm->barrier_no_close_before)
-       break;
-      if ((vm->barrier_no_close_before - now)
-         > (2.0 * BARRIER_MINIMUM_OPEN_LIMIT))
+      while (1)
        {
-         clib_warning ("clock change: would have waited for %.4f seconds",
-                       (vm->barrier_no_close_before - now));
-         break;
+         now = vlib_time_now (vm);
+         /* Barrier hold-down timer expired? */
+         if (now >= vm->barrier_no_close_before)
+           break;
+         if ((vm->barrier_no_close_before - now)
+             > (2.0 * BARRIER_MINIMUM_OPEN_LIMIT))
+           {
+             clib_warning
+               ("clock change: would have waited for %.4f seconds",
+                (vm->barrier_no_close_before - now));
+             break;
+           }
        }
     }
   /* Record time of closure */
@@ -1532,6 +1533,14 @@ vlib_worker_thread_barrier_release (vlib_main_t * vm)
 
   deadline = now + BARRIER_SYNC_TIMEOUT;
 
+  /*
+   * Note when we let go of the barrier.
+   * Workers can use this to derive a reasonably accurate
+   * time offset. See vlib_time_now(...)
+   */
+  vm->time_last_barrier_release = vlib_time_now (vm);
+  CLIB_MEMORY_STORE_BARRIER ();
+
   *vlib_worker_threads->wait_at_barrier = 0;
 
   while (*vlib_worker_threads->workers_at_barrier > 0)
@@ -1830,6 +1839,45 @@ threads_init (vlib_main_t * vm)
 
 VLIB_INIT_FUNCTION (threads_init);
 
+
+static clib_error_t *
+show_clock_command_fn (vlib_main_t * vm,
+                      unformat_input_t * input, vlib_cli_command_t * cmd)
+{
+  int i;
+  f64 now;
+
+  now = vlib_time_now (vm);
+
+  vlib_cli_output (vm, "Time now %.9f", now);
+
+  if (vec_len (vlib_mains) == 1)
+    return 0;
+
+  vlib_cli_output (vm, "Time last barrier release %.9f",
+                  vm->time_last_barrier_release);
+
+  for (i = 1; i < vec_len (vlib_mains); i++)
+    {
+      if (vlib_mains[i] == 0)
+       continue;
+      vlib_cli_output (vm, "Thread %d offset %.9f error %.9f", i,
+                      vlib_mains[i]->time_offset,
+                      vm->time_last_barrier_release -
+                      vlib_mains[i]->time_last_barrier_release);
+    }
+  return 0;
+}
+
+/* *INDENT-OFF* */
+VLIB_CLI_COMMAND (f_command, static) =
+{
+  .path = "show clock",
+  .short_help = "show clock",
+  .function = show_clock_command_fn,
+};
+/* *INDENT-ON* */
+
 /*
  * fd.io coding-style-patch-verification: ON
  *