acl-plugin: make the ACL plugin multicore-capable

Add the logic to be able to use stateful ACLs in a multithreaded setup.

Change-Id: I3b0cfa6ca4ea8f46f61648611c3e97b00c3376b6
Signed-off-by: Andrew Yourtchenko <ayourtch@gmail.com>

1 files changed, 459 insertions, 187 deletions

diff --git a/src/plugins/acl/fa_node.c b/src/plugins/acl/fa_node.c
index c71429e76c6..c6059aae76a 100644
--- a/src/plugins/acl/fa_node.c
+++ b/src/plugins/acl/fa_node.c
@@ -543,6 +543,39 @@ fa_session_get_timeout_type (acl_main_t * am, fa_session_t * sess)
 
 
 static u64
+fa_session_get_shortest_timeout(acl_main_t * am)
+{
+  int timeout_type;
+  u64 timeout = ~0LL;
+  for(timeout_type = 0; timeout_type < ACL_N_TIMEOUTS; timeout_type++) {
+    if (timeout > am->session_timeout_sec[timeout_type]) {
+      timeout = am->session_timeout_sec[timeout_type];
+    }
+  }
+  return timeout;
+}
+
+/*
+ * Get the timeout of the session in a list since its enqueue time.
+ */
+
+static u64
+fa_session_get_list_timeout (acl_main_t * am, fa_session_t * sess)
+{
+  u64 timeout = am->vlib_main->clib_time.clocks_per_second;
+  /*
+   * we have the shortest possible timeout type in all the lists
+   * (see README-multicore for the rationale)
+   */
+  timeout *= fa_session_get_shortest_timeout(am);
+  return timeout;
+}
+
+/*
+ * Get the idle timeout of a session.
+ */
+
+static u64
 fa_session_get_timeout (acl_main_t * am, fa_session_t * sess)
 {
   u64 timeout = am->vlib_main->clib_time.clocks_per_second;
@@ -554,6 +587,7 @@ fa_session_get_timeout (acl_main_t * am, fa_session_t * sess)
 static void
 acl_fa_ifc_init_sessions (acl_main_t * am, int sw_if_index0)
 {
+  /// FIXME-MULTICORE: lock around this function
 #ifdef FA_NODE_VERBOSE_DEBUG
   clib_warning
     ("Initializing bihash for sw_if_index %d num buckets %lu memory size %llu",
@@ -569,68 +603,97 @@ acl_fa_ifc_init_sessions (acl_main_t * am, int sw_if_index0)
     clib_bitmap_set (am->fa_sessions_on_sw_if_index, sw_if_index0, 1);
 }
 
+static inline fa_session_t *get_session_ptr(acl_main_t *am, u16 thread_index, u32 session_index)
+{
+  acl_fa_per_worker_data_t *pw = &am->per_worker_data[thread_index];
+  fa_session_t *sess = pw->fa_sessions_pool + session_index;
+  return sess;
+}
+
 static void
-acl_fa_conn_list_add_session (acl_main_t * am, u32 sess_id, u64 now)
+acl_fa_conn_list_add_session (acl_main_t * am, fa_full_session_id_t sess_id, u64 now)
 {
-  fa_session_t *sess = am->fa_sessions_pool + sess_id;
+  fa_session_t *sess = get_session_ptr(am, sess_id.thread_index, sess_id.session_index);
   u8 list_id = fa_session_get_timeout_type(am, sess);
+  uword thread_index = os_get_thread_index ();
+  acl_fa_per_worker_data_t *pw = &am->per_worker_data[thread_index];
+  /* the retrieved session thread index must be necessarily the same as the one in the key */
+  ASSERT (sess->thread_index == sess_id.thread_index);
+  /* the retrieved session thread index must be the same as current thread */
+  ASSERT (sess->thread_index == thread_index);
   sess->link_enqueue_time = now;
   sess->link_list_id = list_id;
   sess->link_next_idx = ~0;
-  sess->link_prev_idx = am->fa_conn_list_tail[list_id];
-  if (~0 != am->fa_conn_list_tail[list_id]) {
-    fa_session_t *prev_sess = am->fa_sessions_pool + am->fa_conn_list_tail[list_id];
-    prev_sess->link_next_idx = sess_id;
+  sess->link_prev_idx = pw->fa_conn_list_tail[list_id];
+  if (~0 != pw->fa_conn_list_tail[list_id]) {
+    fa_session_t *prev_sess = get_session_ptr(am, thread_index, pw->fa_conn_list_tail[list_id]);
+    prev_sess->link_next_idx = sess_id.session_index;
+    /* We should never try to link with a session on another thread */
+    ASSERT(prev_sess->thread_index == sess->thread_index);
   }
-  am->fa_conn_list_tail[list_id] = sess_id;
+  pw->fa_conn_list_tail[list_id] = sess_id.session_index;
+  pw->serviced_sw_if_index_bitmap = clib_bitmap_set(pw->serviced_sw_if_index_bitmap, sess->sw_if_index, 1);
 
-  if (~0 == am->fa_conn_list_head[list_id]) {
-    am->fa_conn_list_head[list_id] = sess_id;
-    /* If it is a first conn in any list, kick off the cleaner */
+  if (~0 == pw->fa_conn_list_head[list_id]) {
+    pw->fa_conn_list_head[list_id] = sess_id.session_index;
+    /* If it is a first conn in any list, kick the cleaner */
     vlib_process_signal_event (am->vlib_main, am->fa_cleaner_node_index,
                                  ACL_FA_CLEANER_RESCHEDULE, 0);
-
   }
 }
 
-static void
-acl_fa_conn_list_delete_session (acl_main_t *am, u32 sess_id)
+static int
+acl_fa_conn_list_delete_session (acl_main_t *am, fa_full_session_id_t sess_id)
 {
-  fa_session_t *sess = am->fa_sessions_pool + sess_id;
+  uword thread_index = os_get_thread_index ();
+  acl_fa_per_worker_data_t *pw = &am->per_worker_data[thread_index];
+  if (thread_index != sess_id.thread_index) {
+    /* If another thread attempts to delete the session, fail it. */
+#ifdef FA_NODE_VERBOSE_DEBUG
+    clib_warning("thread id in key %d != curr thread index, not deleting");
+#endif
+    return 0;
+  }
+  fa_session_t *sess = get_session_ptr(am, sess_id.thread_index, sess_id.session_index);
+  /* we should never try to delete the session with another thread index */
+  ASSERT(sess->thread_index == thread_index);
   if (~0 != sess->link_prev_idx) {
-    fa_session_t *prev_sess = am->fa_sessions_pool + sess->link_prev_idx;
+    fa_session_t *prev_sess = get_session_ptr(am, thread_index, sess->link_prev_idx);
+    /* the previous session must be in the same list as this one */
+    ASSERT(prev_sess->link_list_id == sess->link_list_id);
     prev_sess->link_next_idx = sess->link_next_idx;
-    if (prev_sess->link_list_id != sess->link_list_id)
-      clib_warning("(prev_sess->link_list_id != sess->link_list_id)");
   }
   if (~0 != sess->link_next_idx) {
-    fa_session_t *next_sess = am->fa_sessions_pool + sess->link_next_idx;
+    fa_session_t *next_sess = get_session_ptr(am, thread_index, sess->link_next_idx);
+    /* The next session must be in the same list as the one we are deleting */
+    ASSERT(next_sess->link_list_id == sess->link_list_id);
     next_sess->link_prev_idx = sess->link_prev_idx;
-    if (next_sess->link_list_id != sess->link_list_id)
-      clib_warning("(next_sess->link_list_id != sess->link_list_id)");
   }
-  if (am->fa_conn_list_head[sess->link_list_id] == sess_id) {
-    am->fa_conn_list_head[sess->link_list_id] = sess->link_next_idx;
+  if (pw->fa_conn_list_head[sess->link_list_id] == sess_id.session_index) {
+    pw->fa_conn_list_head[sess->link_list_id] = sess->link_next_idx;
   }
-  if (am->fa_conn_list_tail[sess->link_list_id] == sess_id) {
-    am->fa_conn_list_tail[sess->link_list_id] = sess->link_prev_idx;
+  if (pw->fa_conn_list_tail[sess->link_list_id] == sess_id.session_index) {
+    pw->fa_conn_list_tail[sess->link_list_id] = sess->link_prev_idx;
   }
+  return 1;
 }
 
-
-int
-acl_fa_session_is_dead (acl_main_t * am, u32 sw_if_index, u64 now,
-			u32 sess_id)
-{
-  return 0;
-}
-
-static void
-acl_fa_restart_timer_for_session (acl_main_t * am, u64 now, u32 sess_id)
+static int
+acl_fa_restart_timer_for_session (acl_main_t * am, u64 now, fa_full_session_id_t sess_id)
 {
-  // fa_session_t *sess = am->fa_sessions_pool + sess_id;
-  acl_fa_conn_list_delete_session(am, sess_id);
-  acl_fa_conn_list_add_session(am, sess_id, now);
+  if (acl_fa_conn_list_delete_session(am, sess_id)) {
+    acl_fa_conn_list_add_session(am, sess_id, now);
+    return 1;
+  } else {
+    /*
+     * Our thread does not own this connection, so we can not delete
+     * The session. To avoid the complicated signaling, we simply
+     * pick the list waiting time to be the shortest of the timeouts.
+     * This way we do not have to do anything special, and let
+     * the regular requeue check take care of everything.
+     */
+    return 0;
+  }
 }
 
 
@@ -648,13 +711,16 @@ acl_fa_track_session (acl_main_t * am, int is_input, u32 sw_if_index, u64 now,
 
 
 static void
-acl_fa_delete_session (acl_main_t * am, u32 sw_if_index, u32 sess_id)
+acl_fa_delete_session (acl_main_t * am, u32 sw_if_index, fa_full_session_id_t sess_id)
 {
-  fa_session_t *sess = (fa_session_t *) am->fa_sessions_pool + sess_id;
+  fa_session_t *sess = get_session_ptr(am, sess_id.thread_index, sess_id.session_index);
+  ASSERT(sess->thread_index == os_get_thread_index ());
   BV (clib_bihash_add_del) (&am->fa_sessions_by_sw_if_index[sw_if_index],
 			    &sess->info.kv, 0);
-  pool_put_index (am->fa_sessions_pool, sess_id);
-  /* Deleting from timer wheel not needed, as the cleaner deals with the timers. */
+  acl_fa_per_worker_data_t *pw = &am->per_worker_data[sess_id.thread_index];
+  pool_put_index (pw->fa_sessions_pool, sess_id.session_index);
+  /* Deleting from timer structures not needed,
+     as the caller must have dealt with the timers. */
   vec_validate (am->fa_session_dels_by_sw_if_index, sw_if_index);
   am->fa_session_dels_by_sw_if_index[sw_if_index]++;
 }
@@ -671,13 +737,114 @@ acl_fa_can_add_session (acl_main_t * am, int is_input, u32 sw_if_index)
   return (curr_sess < am->fa_conn_table_max_entries);
 }
 
+static u64
+acl_fa_get_list_head_expiry_time(acl_main_t *am, acl_fa_per_worker_data_t *pw, u64 now, u16 thread_index, int timeout_type)
+{
+  if (~0 == pw->fa_conn_list_head[timeout_type]) {
+    return ~0LL; // infinity.
+  } else {
+    fa_session_t *sess = get_session_ptr(am, thread_index, pw->fa_conn_list_head[timeout_type]);
+    u64 timeout_time =
+              sess->link_enqueue_time + fa_session_get_list_timeout (am, sess);
+    return timeout_time;
+  }
+}
+
+static int
+acl_fa_conn_time_to_check (acl_main_t *am, acl_fa_per_worker_data_t *pw, u64 now, u16 thread_index, u32 session_index)
+{
+  fa_session_t *sess = get_session_ptr(am, thread_index, session_index);
+  u64 timeout_time =
+              sess->link_enqueue_time + fa_session_get_list_timeout (am, sess);
+  return (timeout_time < now) || (sess->link_enqueue_time <= pw->swipe_end_time);
+}
+
+/*
+ * see if there are sessions ready to be checked,
+ * do the maintenance (requeue or delete), and
+ * return the total number of sessions reclaimed.
+ */
+static int
+acl_fa_check_idle_sessions(acl_main_t *am, u16 thread_index, u64 now)
+{
+  acl_fa_per_worker_data_t *pw = &am->per_worker_data[thread_index];
+  fa_full_session_id_t fsid;
+  fsid.thread_index = thread_index;
+  int total_expired = 0;
+
+  {
+    u8 tt = 0;
+    for(tt = 0; tt < ACL_N_TIMEOUTS; tt++) {
+      while((vec_len(pw->expired) < am->fa_max_deleted_sessions_per_interval)
+	    && (~0 != pw->fa_conn_list_head[tt])
+	    && (acl_fa_conn_time_to_check(am, pw, now, thread_index,
+					  pw->fa_conn_list_head[tt]))) {
+	fsid.session_index = pw->fa_conn_list_head[tt];
+	vec_add1(pw->expired, fsid.session_index);
+	acl_fa_conn_list_delete_session(am, fsid);
+      }
+    }
+  }
+
+  u32 *psid = NULL;
+  vec_foreach (psid, pw->expired)
+  {
+    fsid.session_index = *psid;
+    if (!pool_is_free_index (pw->fa_sessions_pool, fsid.session_index))
+      {
+	fa_session_t *sess = get_session_ptr(am, thread_index, fsid.session_index);
+	u32 sw_if_index = sess->sw_if_index;
+	u64 sess_timeout_time =
+	  sess->last_active_time + fa_session_get_timeout (am, sess);
+	if ((now < sess_timeout_time) && (0 == clib_bitmap_get(pw->pending_clear_sw_if_index_bitmap, sw_if_index)))
+	  {
+#ifdef FA_NODE_VERBOSE_DEBUG
+	    clib_warning ("ACL_FA_NODE_CLEAN: Restarting timer for session %d",
+	       (int) session_index);
+#endif
+	    /* There was activity on the session, so the idle timeout
+	       has not passed. Enqueue for another time period. */
+
+	    acl_fa_conn_list_add_session(am, fsid, now);
+	    pw->cnt_session_timer_restarted++;
+	  }
+	else
+	  {
+#ifdef FA_NODE_VERBOSE_DEBUG
+	    clib_warning ("ACL_FA_NODE_CLEAN: Deleting session %d",
+	       (int) session_index);
+#endif
+	    acl_fa_delete_session (am, sw_if_index, fsid);
+	    pw->cnt_deleted_sessions++;
+	  }
+      }
+    else
+      {
+	pw->cnt_already_deleted_sessions++;
+      }
+  }
+  total_expired = vec_len(pw->expired);
+  /* zero out the vector which we have acted on */
+  if (pw->expired)
+    _vec_len (pw->expired) = 0;
+  /* if we were advancing and reached the end
+   * (no more sessions to recycle), reset the fast-forward timestamp */
+
+  if (pw->swipe_end_time && 0 == total_expired)
+    pw->swipe_end_time = 0;
+  return (total_expired);
+}
+
 always_inline void
-acl_fa_try_recycle_session (acl_main_t * am, int is_input, u32 sw_if_index)
+acl_fa_try_recycle_session (acl_main_t * am, int is_input, u16 thread_index, u32 sw_if_index)
 {
   /* try to recycle a TCP transient session */
+  acl_fa_per_worker_data_t *pw = &am->per_worker_data[thread_index];
   u8 timeout_type = ACL_TIMEOUT_TCP_TRANSIENT;
-  u32 sess_id = am->fa_conn_list_head[timeout_type];
-  if (~0 != sess_id) {
+  fa_full_session_id_t sess_id;
+  sess_id.session_index = pw->fa_conn_list_head[timeout_type];
+  if (~0 != sess_id.session_index) {
+    sess_id.thread_index = thread_index;
     acl_fa_conn_list_delete_session(am, sess_id);
     acl_fa_delete_session(am, sw_if_index, sess_id);
   }
@@ -689,25 +856,28 @@ acl_fa_add_session (acl_main_t * am, int is_input, u32 sw_if_index, u64 now,
 {
   clib_bihash_kv_40_8_t *pkv = &p5tuple->kv;
   clib_bihash_kv_40_8_t kv;
-  u32 sess_id;
-  fa_session_t *sess;
+  fa_full_session_id_t f_sess_id;
+  uword thread_index = os_get_thread_index();
+  acl_fa_per_worker_data_t *pw = &am->per_worker_data[thread_index];
 
-  pool_get (am->fa_sessions_pool, sess);
-  sess_id = sess - am->fa_sessions_pool;
+  f_sess_id.thread_index = thread_index;
+  fa_session_t *sess;
 
+  pool_get_aligned (pw->fa_sessions_pool, sess, CLIB_CACHE_LINE_BYTES);
+  f_sess_id.session_index = sess - pw->fa_sessions_pool;
 
   kv.key[0] = pkv->key[0];
   kv.key[1] = pkv->key[1];
   kv.key[2] = pkv->key[2];
   kv.key[3] = pkv->key[3];
   kv.key[4] = pkv->key[4];
-  kv.value = sess_id;
+  kv.value = f_sess_id.as_u64;
 
   memcpy (sess, pkv, sizeof (pkv->key));
   sess->last_active_time = now;
   sess->sw_if_index = sw_if_index;
   sess->tcp_flags_seen.as_u16 = 0;
-  sess->reserved1 = 0;
+  sess->thread_index = thread_index;
   sess->link_list_id = ~0;
   sess->link_prev_idx = ~0;
   sess->link_next_idx = ~0;
@@ -721,7 +891,7 @@ acl_fa_add_session (acl_main_t * am, int is_input, u32 sw_if_index, u64 now,
 
   BV (clib_bihash_add_del) (&am->fa_sessions_by_sw_if_index[sw_if_index],
 			    &kv, 1);
-  acl_fa_conn_list_add_session(am, sess_id, now);
+  acl_fa_conn_list_add_session(am, f_sess_id, now);
 
   vec_validate (am->fa_session_adds_by_sw_if_index, sw_if_index);
   am->fa_session_adds_by_sw_if_index[sw_if_index]++;
@@ -757,6 +927,7 @@ acl_fa_node_fn (vlib_main_t * vm,
   clib_bihash_kv_40_8_t value_sess;
   vlib_node_runtime_t *error_node;
   u64 now = clib_cpu_time_now ();
+  uword thread_index = os_get_thread_index ();
 
   from = vlib_frame_vector_args (frame);
   n_left_from = frame->n_vectors;
@@ -827,16 +998,19 @@ acl_fa_node_fn (vlib_main_t * vm,
 		{
 		  trace_bitmap |= 0x80000000;
 		  error0 = ACL_FA_ERROR_ACL_EXIST_SESSION;
-		  // FIXME assert(value_sess.value == (0xffffffff & value_sess.value));
-		  u32 sess_id = value_sess.value;
-		  fa_session_t *sess = am->fa_sessions_pool + sess_id;
+		  fa_full_session_id_t f_sess_id;
+
+                  f_sess_id.as_u64 = value_sess.value;
+                  ASSERT(f_sess_id.thread_index < vec_len(vlib_mains));
+
+		  fa_session_t *sess = get_session_ptr(am, f_sess_id.thread_index, f_sess_id.session_index);
 		  int old_timeout_type =
 		    fa_session_get_timeout_type (am, sess);
 		  action =
 		    acl_fa_track_session (am, is_input, sw_if_index0, now,
 					  sess, &fa_5tuple);
 		  /* expose the session id to the tracer */
-		  match_rule_index = sess_id;
+		  match_rule_index = f_sess_id.session_index;
 		  int new_timeout_type =
 		    fa_session_get_timeout_type (am, sess);
 		  acl_check_needed = 0;
@@ -844,7 +1018,7 @@ acl_fa_node_fn (vlib_main_t * vm,
 		  /* Tracking might have changed the session timeout type, e.g. from transient to established */
 		  if (PREDICT_FALSE (old_timeout_type != new_timeout_type))
 		    {
-		      acl_fa_restart_timer_for_session (am, now, sess_id);
+		      acl_fa_restart_timer_for_session (am, now, f_sess_id);
 		      pkts_restart_session_timer++;
 		      trace_bitmap |=
 			0x00010000 + ((0xff & old_timeout_type) << 8) +
@@ -865,7 +1039,7 @@ acl_fa_node_fn (vlib_main_t * vm,
 	      if (2 == action)
 		{
 		  if (!acl_fa_can_add_session (am, is_input, sw_if_index0))
-                    acl_fa_try_recycle_session (am, is_input, sw_if_index0);
+                    acl_fa_try_recycle_session (am, is_input, thread_index, sw_if_index0);
 
 		  if (acl_fa_can_add_session (am, is_input, sw_if_index0))
 		    {
@@ -1024,16 +1198,9 @@ acl_out_ip4_fa_node_fn (vlib_main_t * vm,
 }
 
 /*
- * This process performs all the connection clean up - both for idle connections,
- * as well as receiving the signals to clean up the connections in case of sw_if_index deletion,
- * or (maybe in the future) the connection deletion due to policy reasons.
- *
- * The previous iteration (l2sess) attempted to clean up the connections in small increments,
- * in-band, but the problem it tried to preemptively address (process starvation) is yet to be seen.
- *
- * The approach with a single thread deleting the connections is simpler, thus we use it until
- * there is a real starvation problem to solve.
- *
+ * This process ensures the connection cleanup happens every so often
+ * even in absence of traffic, as well as provides general orchestration
+ * for requests like connection deletion on a given sw_if_index.
  */
 
 
@@ -1056,57 +1223,131 @@ static char *acl_fa_cleaner_error_strings[] = {
 #undef _
 };
 
-static int
-acl_fa_clean_sessions_by_sw_if_index (acl_main_t *am, u32 sw_if_index, u32 *count)
-{
-
-  int undeleted = 0;
-  fa_session_t *sess;
-  uword *dv = NULL;
-  uword *ii;
-
-  pool_foreach(sess, am->fa_sessions_pool, ({
-    if ( (~0 == sw_if_index) || (sw_if_index == sess->sw_if_index) )
-      vec_add1(dv, sess-am->fa_sessions_pool);
-  }));
-  vec_foreach(ii, dv)
-  {
-    sess =  pool_elt_at_index(am->fa_sessions_pool, *ii);
-    acl_fa_delete_session(am, sess->sw_if_index, *ii);
-    (*count)++;
-  }
-
-  pool_foreach(sess, am->fa_sessions_pool, ({
-    if ( (~0 == sw_if_index) || (sw_if_index == sess->sw_if_index) )
-      undeleted++;
-  }));
-  if (undeleted == 0)
-    {
-      if (~0 == sw_if_index)
-        {
-          /* FIXME: clean-up tables ? */
-        }
-      else
-        {
-          /* FIXME: clean-up tables ? */
-        }
-    }
-  return (undeleted == 0);
-}
 /* *INDENT-ON* */
 
 static vlib_node_registration_t acl_fa_session_cleaner_process_node;
+static vlib_node_registration_t acl_fa_worker_session_cleaner_process_node;
 
-static int
-acl_fa_conn_time_to_check (acl_main_t *am, u64 now, u32 session_index)
+/*
+ * Per-worker thread interrupt-driven cleaner thread
+ * to clean idle connections if there are no packets
+ */
+static uword
+acl_fa_worker_conn_cleaner_process(vlib_main_t * vm,
+              vlib_node_runtime_t * rt, vlib_frame_t * f)
 {
-  fa_session_t *sess = am->fa_sessions_pool + session_index;
-  u64 timeout_time =
-              sess->link_enqueue_time + fa_session_get_timeout (am, sess);
-  return (timeout_time < now);
+   acl_main_t *am = &acl_main;
+   u64 now = clib_cpu_time_now ();
+   u16 thread_index = os_get_thread_index ();
+   acl_fa_per_worker_data_t *pw = &am->per_worker_data[thread_index];
+   int num_expired;
+#ifdef FA_NODE_VERBOSE_DEBUG
+   clib_warning("\nacl_fa_worker_conn_cleaner: thread index %d now %lu\n\n", thread_index, now);
+#endif
+   /* allow another interrupt to be queued */
+   pw->interrupt_is_pending = 0;
+   if (pw->clear_in_process) {
+     if (0 == pw->swipe_end_time) {
+       /*
+        * Someone has just set the flag to start clearing.
+        * we do this by combing through the connections up to a "time T"
+        * which is now, and requeueing everything except the expired
+        * connections and those matching the interface(s) being cleared.
+        */
+
+       /*
+        * first filter the sw_if_index bitmap that they want from us, by
+        * a bitmap of sw_if_index for which we actually have connections.
+        */
+       if ((pw->pending_clear_sw_if_index_bitmap == 0)
+           || (pw->serviced_sw_if_index_bitmap == 0)) {
+#ifdef FA_NODE_VERBOSE_DEBUG
+         clib_warning("WORKER-CLEAR: someone tried to call clear, but one of the bitmaps are empty");
+#endif
+	 clib_bitmap_zero(pw->pending_clear_sw_if_index_bitmap);
+       } else {
+#ifdef FA_NODE_VERBOSE_DEBUG
+         clib_warning("WORKER-CLEAR: (before and) swiping sw-if-index bitmap: %U, my serviced bitmap %U",
+                      format_bitmap_hex, pw->pending_clear_sw_if_index_bitmap,
+                      format_bitmap_hex, pw->serviced_sw_if_index_bitmap);
+#endif
+         pw->pending_clear_sw_if_index_bitmap = clib_bitmap_and(pw->pending_clear_sw_if_index_bitmap,
+							      pw->serviced_sw_if_index_bitmap);
+       }
+
+       if (clib_bitmap_is_zero(pw->pending_clear_sw_if_index_bitmap)) {
+         /* if the cross-section is a zero vector, no need to do anything. */
+         clib_warning("WORKER: clearing done - nothing to do");
+         pw->clear_in_process = 0;
+       } else {
+#ifdef FA_NODE_VERBOSE_DEBUG
+         clib_warning("WORKER-CLEAR: swiping sw-if-index bitmap: %U, my serviced bitmap %U",
+                      format_bitmap_hex, pw->pending_clear_sw_if_index_bitmap,
+                      format_bitmap_hex, pw->serviced_sw_if_index_bitmap);
+#endif
+         /* swipe through the connection lists until enqueue timestamps become above "now" */
+         pw->swipe_end_time = now;
+       }
+     }
+   }
+   num_expired = acl_fa_check_idle_sessions(am, thread_index, now);
+   // clib_warning("WORKER-CLEAR: checked %d sessions (clear_in_progress: %d)", num_expired, pw->clear_in_process);
+   if (pw->clear_in_process) {
+     if (0 == num_expired) {
+       /* we were clearing but we could not process any more connections. time to stop. */
+       clib_bitmap_zero(pw->pending_clear_sw_if_index_bitmap);
+       pw->clear_in_process = 0;
+#ifdef FA_NODE_VERBOSE_DEBUG
+       clib_warning("WORKER: clearing done, all done");
+#endif
+     } else {
+#ifdef FA_NODE_VERBOSE_DEBUG
+       clib_warning("WORKER-CLEAR: more work to do, raising interrupt");
+#endif
+       /* should continue clearing.. So could they please sent an interrupt again? */
+       pw->interrupt_is_needed = 1;
+     }
+   } else {
+     if (num_expired >= am->fa_max_deleted_sessions_per_interval) {
+       /* there was too much work, we should get an interrupt ASAP */
+       pw->interrupt_is_needed = 1;
+     } else if (num_expired <= am->fa_min_deleted_sessions_per_interval) {
+       /* signal that they should trigger us less */
+       pw->interrupt_is_unwanted = 1;
+     } else {
+       /* the current rate of interrupts is ok */
+       pw->interrupt_is_needed = 0;
+       pw->interrupt_is_unwanted = 0;
+     }
+   }
+   return 0;
 }
 
+static void
+send_one_worker_interrupt (vlib_main_t * vm, acl_main_t *am, int thread_index)
+{
+  acl_fa_per_worker_data_t *pw = &am->per_worker_data[thread_index];
+  if (!pw->interrupt_is_pending) {
+    vlib_node_set_interrupt_pending (vlib_mains[thread_index],
+                  acl_fa_worker_session_cleaner_process_node.index);
+    pw->interrupt_is_pending = 1;
+    /* if the interrupt was requested, mark that done. */
+    pw->interrupt_is_needed = 0;
+  }
+}
 
+static void
+send_interrupts_to_workers (vlib_main_t * vm, acl_main_t *am)
+{
+  int i;
+  /* Can't use vec_len(am->per_worker_data) since the threads might not have come up yet; */
+  int n_threads = vec_len(vlib_mains);
+  for (i = n_threads > 1 ? 1 : 0; i < n_threads; i++) {
+    send_one_worker_interrupt(vm, am, i);
+  }
+}
+
+/* centralized process to drive per-worker cleaners */
 static uword
 acl_fa_session_cleaner_process (vlib_main_t * vm, vlib_node_runtime_t * rt,
 				vlib_frame_t * f)
@@ -1115,28 +1356,48 @@ acl_fa_session_cleaner_process (vlib_main_t * vm, vlib_node_runtime_t * rt,
   u64 now = clib_cpu_time_now ();
   f64 cpu_cps = vm->clib_time.clocks_per_second;
   u64 next_expire;
-  /* We should call timer wheel at least twice a second */
+  /* We should check if there are connections to clean up - at least twice a second */
   u64 max_timer_wait_interval = cpu_cps / 2;
-  am->fa_current_cleaner_timer_wait_interval = max_timer_wait_interval;
-
-  u32 *expired = NULL;
   uword event_type, *event_data = 0;
+  acl_fa_per_worker_data_t *pw0;
 
+  am->fa_current_cleaner_timer_wait_interval = max_timer_wait_interval;
   am->fa_cleaner_node_index = acl_fa_session_cleaner_process_node.index;
 
   while (1)
     {
-      u32 count_deleted_sessions = 0;
-      u32 count_already_deleted = 0;
       now = clib_cpu_time_now ();
       next_expire = now + am->fa_current_cleaner_timer_wait_interval;
       int has_pending_conns = 0;
+      u16 ti;
       u8 tt;
-      for(tt = 0; tt < ACL_N_TIMEOUTS; tt++)
-        {
-          if (~0 != am->fa_conn_list_head[tt])
+
+      /*
+       * walk over all per-thread list heads of different timeouts,
+       * and see if there are any connections pending.
+       * If there aren't - we do not need to wake up until the
+       * worker code signals that it has added a connection.
+       *
+       * Also, while we are at it, calculate the earliest we need to wake up.
+       */
+      for(ti = 0; ti < vec_len(vlib_mains); ti++) {
+        if (ti >= vec_len(am->per_worker_data)) {
+          continue;
+        }
+        acl_fa_per_worker_data_t *pw = &am->per_worker_data[ti];
+        for(tt = 0; tt < vec_len(pw->fa_conn_list_head); tt++) {
+          u64 head_expiry = acl_fa_get_list_head_expiry_time(am, pw, now, ti, tt);
+          if ((head_expiry < next_expire) && !pw->interrupt_is_pending) {
+#ifdef FA_NODE_VERBOSE_DEBUG
+            clib_warning("Head expiry: %lu, now: %lu, next_expire: %lu (worker: %d, tt: %d)", head_expiry, now, next_expire, ti, tt);
+#endif
+            next_expire = head_expiry;
+	  }
+          if (~0 != pw->fa_conn_list_head[tt]) {
             has_pending_conns = 1;
+          }
         }
+      }
 
       /* If no pending connections then no point in timing out */
       if (!has_pending_conns)
@@ -1155,9 +1416,6 @@ acl_fa_session_cleaner_process (vlib_main_t * vm, vlib_node_runtime_t * rt,
 	    }
 	  else
 	    {
-	      /* Timing wheel code is happier if it is called regularly */
-	      if (timeout > 0.5)
-		timeout = 0.5;
               am->fa_cleaner_cnt_wait_with_timeout++;
 	      (void) vlib_process_wait_for_event_or_clock (vm, timeout);
 	      event_type = vlib_process_get_events (vm, &event_data);
@@ -1175,7 +1433,11 @@ acl_fa_session_cleaner_process (vlib_main_t * vm, vlib_node_runtime_t * rt,
 	  break;
 	case ACL_FA_CLEANER_DELETE_BY_SW_IF_INDEX:
 	  {
+            uword *clear_sw_if_index_bitmap = 0;
 	    uword *sw_if_index0;
+#ifdef FA_NODE_VERBOSE_DEBUG
+	    clib_warning("ACL_FA_CLEANER_DELETE_BY_SW_IF_INDEX received");
+#endif
 	    vec_foreach (sw_if_index0, event_data)
 	    {
               am->fa_cleaner_cnt_delete_by_sw_index++;
@@ -1184,13 +1446,54 @@ acl_fa_session_cleaner_process (vlib_main_t * vm, vlib_node_runtime_t * rt,
 		("ACL_FA_NODE_CLEAN: ACL_FA_CLEANER_DELETE_BY_SW_IF_INDEX: %d",
 		 *sw_if_index0);
 #endif
-	      u32 count = 0;
-	      int result =
-		acl_fa_clean_sessions_by_sw_if_index (am, *sw_if_index0,
-						      &count);
-	      count_deleted_sessions += count;
-              am->fa_cleaner_cnt_delete_by_sw_index_ok += result;
+              clear_sw_if_index_bitmap = clib_bitmap_set(clear_sw_if_index_bitmap, *sw_if_index0, 1);
 	    }
+#ifdef FA_NODE_VERBOSE_DEBUG
+	    clib_warning("ACL_FA_CLEANER_DELETE_BY_SW_IF_INDEX bitmap: %U", format_bitmap_hex, clear_sw_if_index_bitmap);
+#endif
+	    vec_foreach(pw0, am->per_worker_data) {
+              CLIB_MEMORY_BARRIER ();
+	      while (pw0->clear_in_process) {
+                CLIB_MEMORY_BARRIER ();
+#ifdef FA_NODE_VERBOSE_DEBUG
+                clib_warning("ACL_FA_NODE_CLEAN: waiting previous cleaning cycle to finish on %d...", pw0 - am->per_worker_data);
+#endif
+                vlib_process_suspend(vm, 0.0001);
+                if (pw0->interrupt_is_needed) {
+                  send_one_worker_interrupt(vm, am, (pw0 - am->per_worker_data));
+                }
+              }
+              if (pw0->clear_in_process) {
+                clib_warning("ERROR-BUG! Could not initiate cleaning on worker because another cleanup in progress");
+	      } else {
+                pw0->pending_clear_sw_if_index_bitmap = clib_bitmap_dup(clear_sw_if_index_bitmap);
+                pw0->clear_in_process = 1;
+              }
+            }
+            /* send some interrupts so they can start working */
+            send_interrupts_to_workers(vm, am);
+
+            /* now wait till they all complete */
+#ifdef FA_NODE_VERBOSE_DEBUG
+	    clib_warning("CLEANER mains len: %d per-worker len: %d", vec_len(vlib_mains), vec_len(am->per_worker_data));
+#endif
+	    vec_foreach(pw0, am->per_worker_data) {
+              CLIB_MEMORY_BARRIER ();
+	      while (pw0->clear_in_process) {
+                CLIB_MEMORY_BARRIER ();
+#ifdef FA_NODE_VERBOSE_DEBUG
+                clib_warning("ACL_FA_NODE_CLEAN: waiting for my cleaning cycle to finish on %d...", pw0 - am->per_worker_data);
+#endif
+                vlib_process_suspend(vm, 0.0001);
+                if (pw0->interrupt_is_needed) {
+                  send_one_worker_interrupt(vm, am, (pw0 - am->per_worker_data));
+                }
+              }
+            }
+#ifdef FA_NODE_VERBOSE_DEBUG
+            clib_warning("ACL_FA_NODE_CLEAN: cleaning done");
+#endif
+            clib_bitmap_free(clear_sw_if_index_bitmap);
 	  }
 	  break;
 	default:
@@ -1206,74 +1509,34 @@ acl_fa_session_cleaner_process (vlib_main_t * vm, vlib_node_runtime_t * rt,
 	  break;
 	}
 
-      {
-        u8 tt = 0;
-        for(tt = 0; tt < ACL_N_TIMEOUTS; tt++) {
-          while((vec_len(expired) < 2*am->fa_max_deleted_sessions_per_interval)
-                && (~0 != am->fa_conn_list_head[tt])
-                && (acl_fa_conn_time_to_check(am, now,
-                                              am->fa_conn_list_head[tt]))) {
-            u32 sess_id = am->fa_conn_list_head[tt];
-            vec_add1(expired, sess_id);
-            acl_fa_conn_list_delete_session(am, sess_id);
-          }
-        }
-      }
+      send_interrupts_to_workers(vm, am);
 
-      u32 *psid = NULL;
-      vec_foreach (psid, expired)
-      {
-	u32 session_index = *psid;
-	if (!pool_is_free_index (am->fa_sessions_pool, session_index))
-	  {
-	    fa_session_t *sess = am->fa_sessions_pool + session_index;
-	    u32 sw_if_index = sess->sw_if_index;
-	    u64 sess_timeout_time =
-	      sess->last_active_time + fa_session_get_timeout (am, sess);
-	    if (now < sess_timeout_time)
-	      {
-		/* clib_warning ("ACL_FA_NODE_CLEAN: Restarting timer for session %d",
-		   (int) session_index); */
-
-                /* There was activity on the session, so the idle timeout
-                   has not passed. Enqueue for another time period. */
-
-                acl_fa_conn_list_add_session(am, session_index, now);
-
-		/* FIXME: When/if moving to timer wheel,
-                   pretend we did this in the past,
-                   at last_active moment, so the timer is accurate */
-                am->fa_cleaner_cnt_timer_restarted++;
-	      }
-	    else
-	      {
-		/* clib_warning ("ACL_FA_NODE_CLEAN: Deleting session %d",
-		   (int) session_index); */
-		acl_fa_delete_session (am, sw_if_index, session_index);
-                count_deleted_sessions++;
-	      }
-	  }
-	else
-	  {
-	    count_already_deleted++;
-	  }
-      }
-      if (expired)
-	_vec_len (expired) = 0;
       if (event_data)
 	_vec_len (event_data) = 0;
 
-      if (count_deleted_sessions > am->fa_max_deleted_sessions_per_interval) {
-        /* if there was too many sessions to delete, do less waiting around next time */
+
+      int interrupts_needed = 0;
+      int interrupts_unwanted = 0;
+
+      vec_foreach(pw0, am->per_worker_data) {
+        if (pw0->interrupt_is_needed) {
+          interrupts_needed++;
+          /* the per-worker value is reset when sending the interrupt */
+        }
+        if (pw0->interrupt_is_unwanted) {
+          interrupts_unwanted++;
+          pw0->interrupt_is_unwanted = 0;
+        }
+      }
+      if (interrupts_needed) {
+        /* they need more interrupts, do less waiting around next time */
         am->fa_current_cleaner_timer_wait_interval /= 2;
-      } else if (count_deleted_sessions < am->fa_min_deleted_sessions_per_interval) {
-        /* Too few deleted sessions, slowly increase the amount of sleep up to a limit */
+      } else if (interrupts_unwanted) {
+        /* slowly increase the amount of sleep up to a limit */
         if (am->fa_current_cleaner_timer_wait_interval < max_timer_wait_interval)
           am->fa_current_cleaner_timer_wait_interval += cpu_cps * am->fa_cleaner_wait_time_increment;
       }
       am->fa_cleaner_cnt_event_cycles++;
-      am->fa_cleaner_cnt_deleted_sessions += count_deleted_sessions;
-      am->fa_cleaner_cnt_already_deleted += count_already_deleted;
     }
   /* NOT REACHED */
   return 0;
@@ -1307,6 +1570,9 @@ acl_fa_enable_disable (u32 sw_if_index, int is_input, int enable_disable)
   if ((!enable_disable) && (!acl_fa_ifc_has_in_acl (am, sw_if_index))
       && (!acl_fa_ifc_has_out_acl (am, sw_if_index)))
     {
+#ifdef FA_NODE_VERBOSE_DEBUG
+      clib_warning("ENABLE-DISABLE: clean the connections on interface %d", sw_if_index);
+#endif
       vlib_process_signal_event (am->vlib_main, am->fa_cleaner_node_index,
 				 ACL_FA_CLEANER_DELETE_BY_SW_IF_INDEX,
 				 sw_if_index);
@@ -1317,6 +1583,12 @@ acl_fa_enable_disable (u32 sw_if_index, int is_input, int enable_disable)
 
 /* *INDENT-OFF* */
 
+VLIB_REGISTER_NODE (acl_fa_worker_session_cleaner_process_node, static) = {
+  .function = acl_fa_worker_conn_cleaner_process,
+  .name = "acl-plugin-fa-worker-cleaner-process",
+  .type = VLIB_NODE_TYPE_INPUT,
+  .state = VLIB_NODE_STATE_INTERRUPT,
+};
 
 VLIB_REGISTER_NODE (acl_fa_session_cleaner_process_node, static) = {
   .function = acl_fa_session_cleaner_process,