2 * Copyright (c) 2016 Cisco and/or its affiliates.
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at:
7 * http://www.apache.org/licenses/LICENSE-2.0
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
16 #include <vnet/ip/lookup.h>
17 #include <vnet/dpo/load_balance.h>
18 #include <vnet/dpo/load_balance_map.h>
19 #include <vnet/dpo/drop_dpo.h>
20 #include <vppinfra/math.h> /* for fabs */
21 #include <vnet/adj/adj.h>
22 #include <vnet/adj/adj_internal.h>
23 #include <vnet/fib/fib_urpf_list.h>
26 * distribution error tolerance for load-balancing
28 const f64 multipath_next_hop_error_tolerance = 0.1;
33 #define LB_DBG(_lb, _fmt, _args...) \
36 clib_warning("lb:[%s]:" _fmt, \
37 load_balance_format(load_balance_get_index((_lb)), \
43 #define LB_DBG(_p, _fmt, _args...)
48 * Pool of all DPOs. It's not static so the DP can have fast access
50 load_balance_t *load_balance_pool;
53 * The one instance of load-balance main
55 load_balance_main_t load_balance_main;
58 load_balance_get_multipath_tolerance (void)
60 return (multipath_next_hop_error_tolerance);
64 load_balance_get_index (const load_balance_t *lb)
66 return (lb - load_balance_pool);
69 static inline dpo_id_t*
70 load_balance_get_buckets (load_balance_t *lb)
72 if (LB_HAS_INLINE_BUCKETS(lb))
74 return (lb->lb_buckets_inline);
78 return (lb->lb_buckets);
82 static load_balance_t *
83 load_balance_alloc_i (void)
87 pool_get_aligned(load_balance_pool, lb, CLIB_CACHE_LINE_BYTES);
88 memset(lb, 0, sizeof(*lb));
90 lb->lb_map = INDEX_INVALID;
91 lb->lb_urpf = INDEX_INVALID;
92 vlib_validate_combined_counter(&(load_balance_main.lbm_to_counters),
93 load_balance_get_index(lb));
94 vlib_validate_combined_counter(&(load_balance_main.lbm_via_counters),
95 load_balance_get_index(lb));
96 vlib_zero_combined_counter(&(load_balance_main.lbm_to_counters),
97 load_balance_get_index(lb));
98 vlib_zero_combined_counter(&(load_balance_main.lbm_via_counters),
99 load_balance_get_index(lb));
105 load_balance_format (index_t lbi,
106 load_balance_format_flags_t flags,
110 vlib_counter_t to, via;
115 lb = load_balance_get(lbi);
116 vlib_get_combined_counter(&(load_balance_main.lbm_to_counters), lbi, &to);
117 vlib_get_combined_counter(&(load_balance_main.lbm_via_counters), lbi, &via);
118 buckets = load_balance_get_buckets(lb);
120 s = format(s, "%U: ", format_dpo_type, DPO_LOAD_BALANCE);
121 s = format(s, "[index:%d buckets:%d ", lbi, lb->lb_n_buckets);
122 s = format(s, "uRPF:%d ", lb->lb_urpf);
123 s = format(s, "to:[%Ld:%Ld]", to.packets, to.bytes);
124 if (0 != via.packets)
126 s = format(s, " via:[%Ld:%Ld]",
127 via.packets, via.bytes);
131 if (INDEX_INVALID != lb->lb_map)
133 s = format(s, "\n%U%U",
134 format_white_space, indent+4,
135 format_load_balance_map, lb->lb_map, indent+4);
137 for (i = 0; i < lb->lb_n_buckets; i++)
139 s = format(s, "\n%U[%d] %U",
140 format_white_space, indent+2,
143 &buckets[i], indent+6);
149 format_load_balance (u8 * s, va_list * args)
151 index_t lbi = va_arg(*args, index_t);
152 load_balance_format_flags_t flags = va_arg(*args, load_balance_format_flags_t);
154 return (load_balance_format(lbi, flags, 0, s));
157 format_load_balance_dpo (u8 * s, va_list * args)
159 index_t lbi = va_arg(*args, index_t);
160 u32 indent = va_arg(*args, u32);
162 return (load_balance_format(lbi, LOAD_BALANCE_FORMAT_DETAIL, indent, s));
166 static load_balance_t *
167 load_balance_create_i (u32 num_buckets,
168 dpo_proto_t lb_proto,
169 flow_hash_config_t fhc)
173 lb = load_balance_alloc_i();
174 lb->lb_hash_config = fhc;
175 lb->lb_n_buckets = num_buckets;
176 lb->lb_n_buckets_minus_1 = num_buckets-1;
177 lb->lb_proto = lb_proto;
179 if (!LB_HAS_INLINE_BUCKETS(lb))
181 vec_validate_aligned(lb->lb_buckets,
182 lb->lb_n_buckets - 1,
183 CLIB_CACHE_LINE_BYTES);
186 LB_DBG(lb, "create");
192 load_balance_create (u32 n_buckets,
193 dpo_proto_t lb_proto,
194 flow_hash_config_t fhc)
196 return (load_balance_get_index(load_balance_create_i(n_buckets, lb_proto, fhc)));
200 load_balance_set_bucket_i (load_balance_t *lb,
203 const dpo_id_t *next)
205 dpo_stack(DPO_LOAD_BALANCE, lb->lb_proto, &buckets[bucket], next);
209 load_balance_set_bucket (index_t lbi,
211 const dpo_id_t *next)
216 lb = load_balance_get(lbi);
217 buckets = load_balance_get_buckets(lb);
219 ASSERT(bucket < lb->lb_n_buckets);
221 load_balance_set_bucket_i(lb, bucket, buckets, next);
225 load_balance_is_drop (const dpo_id_t *dpo)
229 if (DPO_LOAD_BALANCE != dpo->dpoi_type)
232 lb = load_balance_get(dpo->dpoi_index);
234 if (1 == lb->lb_n_buckets)
236 return (dpo_is_drop(load_balance_get_bucket_i(lb, 0)));
242 load_balance_set_urpf (index_t lbi,
248 lb = load_balance_get(lbi);
251 * packets in flight we see this change. but it's atomic, so :P
256 fib_urpf_list_unlock(old);
257 fib_urpf_list_lock(urpf);
261 load_balance_get_urpf (index_t lbi)
265 lb = load_balance_get(lbi);
267 return (lb->lb_urpf);
271 load_balance_get_bucket (index_t lbi,
276 lb = load_balance_get(lbi);
278 return (load_balance_get_bucket_i(lb, bucket));
282 next_hop_sort_by_weight (load_balance_path_t * n1,
283 load_balance_path_t * n2)
285 return ((int) n1->path_weight - (int) n2->path_weight);
288 /* Given next hop vector is over-written with normalized one with sorted weights and
289 with weights corresponding to the number of adjacencies for each next hop.
290 Returns number of adjacencies in block. */
292 ip_multipath_normalize_next_hops (load_balance_path_t * raw_next_hops,
293 load_balance_path_t ** normalized_next_hops,
295 f64 multipath_next_hop_error_tolerance)
297 load_balance_path_t * nhs;
298 uword n_nhs, n_adj, n_adj_left, i, sum_weight;
301 n_nhs = vec_len (raw_next_hops);
306 /* Allocate enough space for 2 copies; we'll use second copy to save original weights. */
307 nhs = *normalized_next_hops;
308 vec_validate (nhs, 2*n_nhs - 1);
310 /* Fast path: 1 next hop in block. */
314 nhs[0] = raw_next_hops[0];
315 nhs[0].path_weight = 1;
323 int cmp = next_hop_sort_by_weight (&raw_next_hops[0], &raw_next_hops[1]) < 0;
326 nhs[0] = raw_next_hops[cmp];
327 nhs[1] = raw_next_hops[cmp ^ 1];
329 /* Fast path: equal cost multipath with 2 next hops. */
330 if (nhs[0].path_weight == nhs[1].path_weight)
332 nhs[0].path_weight = nhs[1].path_weight = 1;
340 clib_memcpy (nhs, raw_next_hops, n_nhs * sizeof (raw_next_hops[0]));
341 qsort (nhs, n_nhs, sizeof (nhs[0]), (void *) next_hop_sort_by_weight);
344 /* Find total weight to normalize weights. */
346 for (i = 0; i < n_nhs; i++)
347 sum_weight += nhs[i].path_weight;
349 /* In the unlikely case that all weights are given as 0, set them all to 1. */
352 for (i = 0; i < n_nhs; i++)
353 nhs[i].path_weight = 1;
357 /* Save copies of all next hop weights to avoid being overwritten in loop below. */
358 for (i = 0; i < n_nhs; i++)
359 nhs[n_nhs + i].path_weight = nhs[i].path_weight;
361 /* Try larger and larger power of 2 sized adjacency blocks until we
362 find one where traffic flows to within 1% of specified weights. */
363 for (n_adj = max_pow2 (n_nhs); ; n_adj *= 2)
367 norm = n_adj / ((f64) sum_weight);
369 for (i = 0; i < n_nhs; i++)
371 f64 nf = nhs[n_nhs + i].path_weight * norm; /* use saved weights */
372 word n = flt_round_nearest (nf);
374 n = n > n_adj_left ? n_adj_left : n;
376 error += fabs (nf - n);
377 nhs[i].path_weight = n;
379 if (0 == nhs[i].path_weight)
382 * when the weight skew is high (norm is small) and n == nf.
383 * without this correction the path with a low weight would have
384 * no represenation in the load-balanace - don't want that.
385 * If the weight skew is high so the load-balance has many buckets
386 * to allow it. pays ya money takes ya choice.
393 nhs[0].path_weight += n_adj_left;
395 /* Less than 5% average error per adjacency with this size adjacency block? */
396 if (error <= multipath_next_hop_error_tolerance*n_adj)
398 /* Truncate any next hops with zero weight. */
405 /* Save vector for next call. */
406 *normalized_next_hops = nhs;
407 *sum_weight_in = sum_weight;
411 static load_balance_path_t *
412 load_balance_multipath_next_hop_fixup (load_balance_path_t *nhs,
413 dpo_proto_t drop_proto)
415 if (0 == vec_len(nhs))
417 load_balance_path_t *nh;
420 * we need something for the load-balance. so use the drop
422 vec_add2(nhs, nh, 1);
425 dpo_copy(&nh->path_dpo, drop_dpo_get(drop_proto));
432 * Fill in adjacencies in block based on corresponding
433 * next hop adjacencies.
436 load_balance_fill_buckets (load_balance_t *lb,
437 load_balance_path_t *nhs,
441 load_balance_path_t * nh;
447 * the next-hops have normalised weights. that means their sum is the number
448 * of buckets we need to fill.
450 vec_foreach (nh, nhs)
452 for (ii = 0; ii < nh->path_weight; ii++)
454 ASSERT(bucket < n_buckets);
455 load_balance_set_bucket_i(lb, bucket++, buckets, &nh->path_dpo);
461 load_balance_set_n_buckets (load_balance_t *lb,
464 lb->lb_n_buckets = n_buckets;
465 lb->lb_n_buckets_minus_1 = n_buckets-1;
469 load_balance_multipath_update (const dpo_id_t *dpo,
470 load_balance_path_t * raw_next_hops,
471 load_balance_flags_t flags)
473 u32 sum_of_weights,n_buckets, ii;
474 load_balance_path_t * nh, * nhs;
475 index_t lbmi, old_lbmi;
481 ASSERT(DPO_LOAD_BALANCE == dpo->dpoi_type);
482 lb = load_balance_get(dpo->dpoi_index);
484 load_balance_multipath_next_hop_fixup(raw_next_hops,
487 ip_multipath_normalize_next_hops(raw_next_hops,
490 multipath_next_hop_error_tolerance);
492 ASSERT (n_buckets >= vec_len (raw_next_hops));
495 * Save the old load-balance map used, and get a new one if required.
497 old_lbmi = lb->lb_map;
498 if (flags & LOAD_BALANCE_FLAG_USES_MAP)
500 lbmi = load_balance_map_add_or_lock(n_buckets, sum_of_weights, nhs);
504 lbmi = INDEX_INVALID;
507 if (0 == lb->lb_n_buckets)
510 * first time initialisation. no packets inflight, so we can write
513 load_balance_set_n_buckets(lb, n_buckets);
515 if (!LB_HAS_INLINE_BUCKETS(lb))
516 vec_validate_aligned(lb->lb_buckets,
517 lb->lb_n_buckets - 1,
518 CLIB_CACHE_LINE_BYTES);
520 load_balance_fill_buckets(lb, nhs,
521 load_balance_get_buckets(lb),
528 * This is a modification of an existing load-balance.
529 * We need to ensure that packets inflight see a consistent state, that
530 * is the number of reported buckets the LB has (read from
531 * lb_n_buckets_minus_1) is not more than it actually has. So if the
532 * number of buckets is increasing, we must update the bucket array first,
533 * then the reported number. vice-versa if the number of buckets goes down.
535 if (n_buckets == lb->lb_n_buckets)
538 * no change in the number of buckets. we can simply fill what
539 * is new over what is old.
541 load_balance_fill_buckets(lb, nhs,
542 load_balance_get_buckets(lb),
546 else if (n_buckets > lb->lb_n_buckets)
549 * we have more buckets. the old load-balance map (if there is one)
550 * will remain valid, i.e. mapping to indices within range, so we
553 if (n_buckets > LB_NUM_INLINE_BUCKETS &&
554 lb->lb_n_buckets <= LB_NUM_INLINE_BUCKETS)
557 * the new increased number of buckets is crossing the threshold
558 * from the inline storage to out-line. Alloc the outline buckets
559 * first, then fixup the number. then reset the inlines.
561 ASSERT(NULL == lb->lb_buckets);
562 vec_validate_aligned(lb->lb_buckets,
564 CLIB_CACHE_LINE_BYTES);
566 load_balance_fill_buckets(lb, nhs,
569 CLIB_MEMORY_BARRIER();
570 load_balance_set_n_buckets(lb, n_buckets);
572 CLIB_MEMORY_BARRIER();
574 for (ii = 0; ii < LB_NUM_INLINE_BUCKETS; ii++)
576 dpo_reset(&lb->lb_buckets_inline[ii]);
581 if (n_buckets <= LB_NUM_INLINE_BUCKETS)
584 * we are not crossing the threshold and it's still inline buckets.
585 * we can write the new on the old..
587 load_balance_fill_buckets(lb, nhs,
588 load_balance_get_buckets(lb),
590 CLIB_MEMORY_BARRIER();
591 load_balance_set_n_buckets(lb, n_buckets);
596 * we are not crossing the threshold. We need a new bucket array to
597 * hold the increased number of choices.
599 dpo_id_t *new_buckets, *old_buckets, *tmp_dpo;
602 old_buckets = load_balance_get_buckets(lb);
604 vec_validate_aligned(new_buckets,
606 CLIB_CACHE_LINE_BYTES);
608 load_balance_fill_buckets(lb, nhs, new_buckets, n_buckets);
609 CLIB_MEMORY_BARRIER();
610 lb->lb_buckets = new_buckets;
611 CLIB_MEMORY_BARRIER();
612 load_balance_set_n_buckets(lb, n_buckets);
614 vec_foreach(tmp_dpo, old_buckets)
618 vec_free(old_buckets);
623 * buckets fixed. ready for the MAP update.
630 * bucket size shrinkage.
631 * Any map we have will be based on the old
632 * larger number of buckets, so will be translating to indices
633 * out of range. So the new MAP must be installed first.
636 CLIB_MEMORY_BARRIER();
639 if (n_buckets <= LB_NUM_INLINE_BUCKETS &&
640 lb->lb_n_buckets > LB_NUM_INLINE_BUCKETS)
643 * the new decreased number of buckets is crossing the threshold
644 * from out-line storage to inline:
645 * 1 - Fill the inline buckets,
646 * 2 - fixup the number (and this point the inline buckets are
648 * 3 - free the outline buckets
650 load_balance_fill_buckets(lb, nhs,
651 lb->lb_buckets_inline,
653 CLIB_MEMORY_BARRIER();
654 load_balance_set_n_buckets(lb, n_buckets);
655 CLIB_MEMORY_BARRIER();
657 vec_foreach(tmp_dpo, lb->lb_buckets)
661 vec_free(lb->lb_buckets);
666 * not crossing the threshold.
667 * 1 - update the number to the smaller size
668 * 2 - write the new buckets
669 * 3 - reset those no longer used.
674 old_n_buckets = lb->lb_n_buckets;
675 buckets = load_balance_get_buckets(lb);
677 load_balance_set_n_buckets(lb, n_buckets);
678 CLIB_MEMORY_BARRIER();
680 load_balance_fill_buckets(lb, nhs,
684 for (ii = old_n_buckets-n_buckets; ii < old_n_buckets; ii++)
686 dpo_reset(&buckets[ii]);
692 vec_foreach (nh, nhs)
694 dpo_reset(&nh->path_dpo);
698 load_balance_map_unlock(old_lbmi);
702 load_balance_lock (dpo_id_t *dpo)
706 lb = load_balance_get(dpo->dpoi_index);
712 load_balance_destroy (load_balance_t *lb)
717 buckets = load_balance_get_buckets(lb);
719 for (i = 0; i < lb->lb_n_buckets; i++)
721 dpo_reset(&buckets[i]);
724 LB_DBG(lb, "destroy");
725 if (!LB_HAS_INLINE_BUCKETS(lb))
727 vec_free(lb->lb_buckets);
730 fib_urpf_list_unlock(lb->lb_urpf);
731 load_balance_map_unlock(lb->lb_map);
733 pool_put(load_balance_pool, lb);
737 load_balance_unlock (dpo_id_t *dpo)
741 lb = load_balance_get(dpo->dpoi_index);
745 if (0 == lb->lb_locks)
747 load_balance_destroy(lb);
752 load_balance_mem_show (void)
754 fib_show_memory_usage("load-balance",
755 pool_elts(load_balance_pool),
756 pool_len(load_balance_pool),
757 sizeof(load_balance_t));
758 load_balance_map_show_mem();
761 const static dpo_vft_t lb_vft = {
762 .dv_lock = load_balance_lock,
763 .dv_unlock = load_balance_unlock,
764 .dv_format = format_load_balance_dpo,
765 .dv_mem_show = load_balance_mem_show,
769 * @brief The per-protocol VLIB graph nodes that are assigned to a load-balance
772 * this means that these graph nodes are ones from which a load-balance is the
773 * parent object in the DPO-graph.
775 * We do not list all the load-balance nodes, such as the *-lookup. instead
776 * we are relying on the correct use of the .sibling_of field when setting
777 * up these sibling nodes.
779 const static char* const load_balance_ip4_nodes[] =
784 const static char* const load_balance_ip6_nodes[] =
789 const static char* const load_balance_mpls_nodes[] =
794 const static char* const load_balance_l2_nodes[] =
799 const static char* const * const load_balance_nodes[DPO_PROTO_NUM] =
801 [DPO_PROTO_IP4] = load_balance_ip4_nodes,
802 [DPO_PROTO_IP6] = load_balance_ip6_nodes,
803 [DPO_PROTO_MPLS] = load_balance_mpls_nodes,
804 [DPO_PROTO_ETHERNET] = load_balance_l2_nodes,
808 load_balance_module_init (void)
810 dpo_register(DPO_LOAD_BALANCE, &lb_vft, load_balance_nodes);
812 load_balance_map_module_init();
815 static clib_error_t *
816 load_balance_show (vlib_main_t * vm,
817 unformat_input_t * input,
818 vlib_cli_command_t * cmd)
820 index_t lbi = INDEX_INVALID;
822 while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
824 if (unformat (input, "%d", &lbi))
830 if (INDEX_INVALID != lbi)
832 vlib_cli_output (vm, "%U", format_load_balance, lbi,
833 LOAD_BALANCE_FORMAT_DETAIL);
839 pool_foreach(lb, load_balance_pool,
841 vlib_cli_output (vm, "%U", format_load_balance,
842 load_balance_get_index(lb),
843 LOAD_BALANCE_FORMAT_NONE);
850 VLIB_CLI_COMMAND (load_balance_show_command, static) = {
851 .path = "show load-balance",
852 .short_help = "show load-balance [<index>]",
853 .function = load_balance_show,
858 ip_flow_hash (void *data)
860 ip4_header_t *iph = (ip4_header_t *) data;
862 if ((iph->ip_version_and_header_length & 0xF0) == 0x40)
863 return ip4_compute_flow_hash (iph, IP_FLOW_HASH_DEFAULT);
865 return ip6_compute_flow_hash ((ip6_header_t *) iph, IP_FLOW_HASH_DEFAULT);
871 return (*((u64 *) m) & 0xffffffffffff);
875 l2_flow_hash (vlib_buffer_t * b0)
877 ethernet_header_t *eh;
879 uword is_ip, eh_size;
882 eh = vlib_buffer_get_current (b0);
883 eh_type = clib_net_to_host_u16 (eh->type);
884 eh_size = ethernet_buffer_header_size (b0);
886 is_ip = (eh_type == ETHERNET_TYPE_IP4 || eh_type == ETHERNET_TYPE_IP6);
888 /* since we have 2 cache lines, use them */
890 a = ip_flow_hash ((u8 *) vlib_buffer_get_current (b0) + eh_size);
894 b = mac_to_u64 ((u8 *) eh->dst_address);
895 c = mac_to_u64 ((u8 *) eh->src_address);
896 hash_mix64 (a, b, c);
901 typedef struct load_balance_trace_t_
904 } load_balance_trace_t;
907 l2_load_balance (vlib_main_t * vm,
908 vlib_node_runtime_t * node,
909 vlib_frame_t * frame)
911 u32 n_left_from, next_index, *from, *to_next;
913 from = vlib_frame_vector_args (frame);
914 n_left_from = frame->n_vectors;
916 next_index = node->cached_next_index;
918 while (n_left_from > 0)
922 vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
924 while (n_left_from > 0 && n_left_to_next > 0)
927 u32 bi0, lbi0, next0;
928 const dpo_id_t *dpo0;
929 const load_balance_t *lb0;
938 b0 = vlib_get_buffer (vm, bi0);
940 /* lookup dst + src mac */
941 lbi0 = vnet_buffer (b0)->ip.adj_index[VLIB_TX];
942 lb0 = load_balance_get(lbi0);
944 vnet_buffer(b0)->ip.flow_hash = l2_flow_hash(b0);
946 dpo0 = load_balance_get_bucket_i(lb0,
947 vnet_buffer(b0)->ip.flow_hash &
948 (lb0->lb_n_buckets_minus_1));
950 next0 = dpo0->dpoi_next_node;
951 vnet_buffer (b0)->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;
953 if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
955 load_balance_trace_t *tr = vlib_add_trace (vm, node, b0,
959 vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
960 n_left_to_next, bi0, next0);
963 vlib_put_next_frame (vm, node, next_index, n_left_to_next);
966 return frame->n_vectors;
970 format_load_balance_trace (u8 * s, va_list * args)
972 CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
973 CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
974 load_balance_trace_t *t = va_arg (*args, load_balance_trace_t *);
976 s = format (s, "L2-load-balance: index %d", t->lb_index);
983 VLIB_REGISTER_NODE (l2_load_balance_node) = {
984 .function = l2_load_balance,
985 .name = "l2-load-balance",
986 .vector_size = sizeof (u32),
988 .format_trace = format_load_balance_trace,