src/vnet/handoff.c - fdio/vpp - Gitiles


 /*
  * Copyright (c) 2016 Cisco and/or its affiliates.
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at:
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include <vnet/vnet.h>
 #include <vppinfra/xxhash.h>
 #include <vlib/threads.h>
 #include <vnet/handoff.h>
 #include <vnet/feature/feature.h>

 typedef struct
 {
   uword *workers_bitmap;
   u32 *workers;
 } per_inteface_handoff_data_t;

 typedef struct
 {
   u32 cached_next_index;
   u32 num_workers;
   u32 first_worker_index;

   per_inteface_handoff_data_t *if_data;

   /* Worker handoff index */
   u32 frame_queue_index;

   /* convenience variables */
   vlib_main_t *vlib_main;
   vnet_main_t *vnet_main;

     u64 (*hash_fn) (ethernet_header_t *);
 } handoff_main_t;

 handoff_main_t handoff_main;
 vlib_node_registration_t handoff_dispatch_node;

 typedef struct
 {
   u32 sw_if_index;
   u32 next_worker_index;
   u32 buffer_index;
 } worker_handoff_trace_t;

 /* packet trace format function */
 static u8 *
 format_worker_handoff_trace (u8 * s, va_list * args)
 {
   CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
   CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
   worker_handoff_trace_t *t = va_arg (*args, worker_handoff_trace_t *);

   s =
     format (s, "worker-handoff: sw_if_index %d, next_worker %d, buffer 0x%x",
 	    t->sw_if_index, t->next_worker_index, t->buffer_index);
   return s;
 }

 vlib_node_registration_t handoff_node;

 static uword
 worker_handoff_node_fn (vlib_main_t * vm,
 			vlib_node_runtime_t * node, vlib_frame_t * frame)
 {
   handoff_main_t *hm = &handoff_main;
   vlib_thread_main_t *tm = vlib_get_thread_main ();
   u32 n_left_from, *from;
   static __thread vlib_frame_queue_elt_t **handoff_queue_elt_by_worker_index;
   static __thread vlib_frame_queue_t **congested_handoff_queue_by_worker_index
     = 0;
   vlib_frame_queue_elt_t *hf = 0;
   int i;
   u32 n_left_to_next_worker = 0, *to_next_worker = 0;
   u32 next_worker_index = 0;
   u32 current_worker_index = ~0;

   if (PREDICT_FALSE (handoff_queue_elt_by_worker_index == 0))
     {
       vec_validate (handoff_queue_elt_by_worker_index, tm->n_vlib_mains - 1);

       vec_validate_init_empty (congested_handoff_queue_by_worker_index,
 			       hm->first_worker_index + hm->num_workers - 1,
 			       (vlib_frame_queue_t *) (~0));
     }

   from = vlib_frame_vector_args (frame);
   n_left_from = frame->n_vectors;

   while (n_left_from > 0)
     {
       u32 bi0;
       vlib_buffer_t *b0;
       u32 sw_if_index0;
       u32 hash;
       u64 hash_key;
       per_inteface_handoff_data_t *ihd0;
       u32 index0;

       bi0 = from[0];
       from += 1;
       n_left_from -= 1;

       b0 = vlib_get_buffer (vm, bi0);
       sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
       ASSERT (hm->if_data);
       ihd0 = vec_elt_at_index (hm->if_data, sw_if_index0);

       next_worker_index = hm->first_worker_index;

       /*
        * Force unknown traffic onto worker 0,
        * and into ethernet-input. $$$$ add more hashes.
        */

       /* Compute ingress LB hash */
       hash_key = hm->hash_fn ((ethernet_header_t *) b0->data);
       hash = (u32) clib_xxhash (hash_key);

       /* if input node did not specify next index, then packet
          should go to eternet-input */
       if (PREDICT_FALSE ((b0->flags & VNET_BUFFER_F_HANDOFF_NEXT_VALID) == 0))
 	vnet_buffer (b0)->handoff.next_index =
 	  HANDOFF_DISPATCH_NEXT_ETHERNET_INPUT;
       else if (vnet_buffer (b0)->handoff.next_index ==
 	       HANDOFF_DISPATCH_NEXT_IP4_INPUT
 	       || vnet_buffer (b0)->handoff.next_index ==
 	       HANDOFF_DISPATCH_NEXT_IP6_INPUT
 	       || vnet_buffer (b0)->handoff.next_index ==
 	       HANDOFF_DISPATCH_NEXT_MPLS_INPUT)
 	vlib_buffer_advance (b0, (sizeof (ethernet_header_t)));

       if (PREDICT_TRUE (is_pow2 (vec_len (ihd0->workers))))
 	index0 = hash & (vec_len (ihd0->workers) - 1);
       else
 	index0 = hash % vec_len (ihd0->workers);

       next_worker_index += ihd0->workers[index0];

       if (next_worker_index != current_worker_index)
 	{
 	  if (hf)
 	    hf->n_vectors = VLIB_FRAME_SIZE - n_left_to_next_worker;

 	  hf = vlib_get_worker_handoff_queue_elt (hm->frame_queue_index,
 						  next_worker_index,
 						  handoff_queue_elt_by_worker_index);

 	  n_left_to_next_worker = VLIB_FRAME_SIZE - hf->n_vectors;
 	  to_next_worker = &hf->buffer_index[hf->n_vectors];
 	  current_worker_index = next_worker_index;
 	}

       /* enqueue to correct worker thread */
       to_next_worker[0] = bi0;
       to_next_worker++;
       n_left_to_next_worker--;

       if (n_left_to_next_worker == 0)
 	{
 	  hf->n_vectors = VLIB_FRAME_SIZE;
 	  vlib_put_frame_queue_elt (hf);
 	  current_worker_index = ~0;
 	  handoff_queue_elt_by_worker_index[next_worker_index] = 0;
 	  hf = 0;
 	}

       if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
 			 && (b0->flags & VLIB_BUFFER_IS_TRACED)))
 	{
 	  worker_handoff_trace_t *t =
 	    vlib_add_trace (vm, node, b0, sizeof (*t));
 	  t->sw_if_index = sw_if_index0;
 	  t->next_worker_index = next_worker_index - hm->first_worker_index;
 	  t->buffer_index = bi0;
 	}

     }

   if (hf)
     hf->n_vectors = VLIB_FRAME_SIZE - n_left_to_next_worker;

   /* Ship frames to the worker nodes */
   for (i = 0; i < vec_len (handoff_queue_elt_by_worker_index); i++)
     {
       if (handoff_queue_elt_by_worker_index[i])
 	{
 	  hf = handoff_queue_elt_by_worker_index[i];
 	  /*
 	   * It works better to let the handoff node
 	   * rate-adapt, always ship the handoff queue element.
 	   */
 	  if (1 || hf->n_vectors == hf->last_n_vectors)
 	    {
 	      vlib_put_frame_queue_elt (hf);
 	      handoff_queue_elt_by_worker_index[i] = 0;
 	    }
 	  else
 	    hf->last_n_vectors = hf->n_vectors;
 	}
       congested_handoff_queue_by_worker_index[i] =
 	(vlib_frame_queue_t *) (~0);
     }
   hf = 0;
   current_worker_index = ~0;
   return frame->n_vectors;
 }

 /* *INDENT-OFF* */
 VLIB_REGISTER_NODE (worker_handoff_node) = {
   .function = worker_handoff_node_fn,
   .name = "worker-handoff",
   .vector_size = sizeof (u32),
   .format_trace = format_worker_handoff_trace,
   .type = VLIB_NODE_TYPE_INTERNAL,

   .n_next_nodes = 1,
   .next_nodes = {
     [0] = "error-drop",
   },
 };

 VLIB_NODE_FUNCTION_MULTIARCH (worker_handoff_node, worker_handoff_node_fn)
 /* *INDENT-ON* */

 int
 interface_handoff_enable_disable (vlib_main_t * vm, u32 sw_if_index,
 				  uword * bitmap, int enable_disable)
 {
   handoff_main_t *hm = &handoff_main;
   vnet_sw_interface_t *sw;
   vnet_main_t *vnm = vnet_get_main ();
   per_inteface_handoff_data_t *d;
   int i, rv = 0;

   if (pool_is_free_index (vnm->interface_main.sw_interfaces, sw_if_index))
     return VNET_API_ERROR_INVALID_SW_IF_INDEX;

   sw = vnet_get_sw_interface (vnm, sw_if_index);
   if (sw->type != VNET_SW_INTERFACE_TYPE_HARDWARE)
     return VNET_API_ERROR_INVALID_SW_IF_INDEX;

   if (clib_bitmap_last_set (bitmap) >= hm->num_workers)
     return VNET_API_ERROR_INVALID_WORKER;

   if (hm->frame_queue_index == ~0)
     hm->frame_queue_index =
       vlib_frame_queue_main_init (handoff_dispatch_node.index, 0);

   vec_validate (hm->if_data, sw_if_index);
   d = vec_elt_at_index (hm->if_data, sw_if_index);

   vec_free (d->workers);
   vec_free (d->workers_bitmap);

   if (enable_disable)
     {
       d->workers_bitmap = bitmap;
       /* *INDENT-OFF* */
       clib_bitmap_foreach (i, bitmap,
 	({
 	  vec_add1(d->workers, i);
 	}));
       /* *INDENT-ON* */
     }

   vnet_feature_enable_disable ("device-input", "worker-handoff",
 			       sw_if_index, enable_disable, 0, 0);
   return rv;
 }

 static clib_error_t *
 set_interface_handoff_command_fn (vlib_main_t * vm,
 				  unformat_input_t * input,
 				  vlib_cli_command_t * cmd)
 {
   handoff_main_t *hm = &handoff_main;
   u32 sw_if_index = ~0;
   int enable_disable = 1;
   uword *bitmap = 0;
   u32 sym = ~0;

   int rv = 0;

   while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
     {
       if (unformat (input, "disable"))
 	enable_disable = 0;
       else if (unformat (input, "workers %U", unformat_bitmap_list, &bitmap))
 	;
       else if (unformat (input, "%U", unformat_vnet_sw_interface,
 			 vnet_get_main (), &sw_if_index))
 	;
       else if (unformat (input, "symmetrical"))
 	sym = 1;
       else if (unformat (input, "asymmetrical"))
 	sym = 0;
       else
 	break;
     }

   if (sw_if_index == ~0)
     return clib_error_return (0, "Please specify an interface...");

   if (bitmap == 0)
     return clib_error_return (0, "Please specify list of workers...");

   rv =
     interface_handoff_enable_disable (vm, sw_if_index, bitmap,
 				      enable_disable);

   switch (rv)
     {
     case 0:
       break;

     case VNET_API_ERROR_INVALID_SW_IF_INDEX:
       return clib_error_return (0, "Invalid interface");
       break;

     case VNET_API_ERROR_INVALID_WORKER:
       return clib_error_return (0, "Invalid worker(s)");
       break;

     case VNET_API_ERROR_UNIMPLEMENTED:
       return clib_error_return (0,
 				"Device driver doesn't support redirection");
       break;

     default:
       return clib_error_return (0, "unknown return value %d", rv);
     }

   if (sym == 1)
     hm->hash_fn = eth_get_sym_key;
   else if (sym == 0)
     hm->hash_fn = eth_get_key;

   return 0;
 }

 /* *INDENT-OFF* */
 VLIB_CLI_COMMAND (set_interface_handoff_command, static) = {
   .path = "set interface handoff",
   .short_help =
   "set interface handoff <interface-name> workers <workers-list> [symmetrical|asymmetrical]",
   .function = set_interface_handoff_command_fn,
 };
 /* *INDENT-ON* */

 typedef struct
 {
   u32 buffer_index;
   u32 next_index;
   u32 sw_if_index;
 } handoff_dispatch_trace_t;

 /* packet trace format function */
 static u8 *
 format_handoff_dispatch_trace (u8 * s, va_list * args)
 {
   CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
   CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
   handoff_dispatch_trace_t *t = va_arg (*args, handoff_dispatch_trace_t *);

   s = format (s, "handoff-dispatch: sw_if_index %d next_index %d buffer 0x%x",
 	      t->sw_if_index, t->next_index, t->buffer_index);
   return s;
 }

 #define foreach_handoff_dispatch_error \
 _(EXAMPLE, "example packets")

 typedef enum
 {
 #define _(sym,str) HANDOFF_DISPATCH_ERROR_##sym,
   foreach_handoff_dispatch_error
 #undef _
     HANDOFF_DISPATCH_N_ERROR,
 } handoff_dispatch_error_t;

 static char *handoff_dispatch_error_strings[] = {
 #define _(sym,string) string,
   foreach_handoff_dispatch_error
 #undef _
 };

 static uword
 handoff_dispatch_node_fn (vlib_main_t * vm,
 			  vlib_node_runtime_t * node, vlib_frame_t * frame)
 {
   u32 n_left_from, *from, *to_next;
   handoff_dispatch_next_t next_index;

   from = vlib_frame_vector_args (frame);
   n_left_from = frame->n_vectors;
   next_index = node->cached_next_index;

   while (n_left_from > 0)
     {
       u32 n_left_to_next;

       vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);

       while (n_left_from >= 4 && n_left_to_next >= 2)
 	{
 	  u32 bi0, bi1;
 	  vlib_buffer_t *b0, *b1;
 	  u32 next0, next1;
 	  u32 sw_if_index0, sw_if_index1;

 	  /* Prefetch next iteration. */
 	  {
 	    vlib_buffer_t *p2, *p3;

 	    p2 = vlib_get_buffer (vm, from[2]);
 	    p3 = vlib_get_buffer (vm, from[3]);

 	    vlib_prefetch_buffer_header (p2, LOAD);
 	    vlib_prefetch_buffer_header (p3, LOAD);
 	  }

 	  /* speculatively enqueue b0 and b1 to the current next frame */
 	  to_next[0] = bi0 = from[0];
 	  to_next[1] = bi1 = from[1];
 	  from += 2;
 	  to_next += 2;
 	  n_left_from -= 2;
 	  n_left_to_next -= 2;

 	  b0 = vlib_get_buffer (vm, bi0);
 	  b1 = vlib_get_buffer (vm, bi1);

 	  next0 = vnet_buffer (b0)->handoff.next_index;
 	  next1 = vnet_buffer (b1)->handoff.next_index;

 	  if (PREDICT_FALSE (vm->trace_main.trace_active_hint))
 	    {
 	      if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
 		{
 		  vlib_trace_buffer (vm, node, next0, b0,	/* follow_chain */
 				     0);
 		  handoff_dispatch_trace_t *t =
 		    vlib_add_trace (vm, node, b0, sizeof (*t));
 		  sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
 		  t->sw_if_index = sw_if_index0;
 		  t->next_index = next0;
 		  t->buffer_index = bi0;
 		}
 	      if (PREDICT_FALSE (b1->flags & VLIB_BUFFER_IS_TRACED))
 		{
 		  vlib_trace_buffer (vm, node, next1, b1,	/* follow_chain */
 				     0);
 		  handoff_dispatch_trace_t *t =
 		    vlib_add_trace (vm, node, b1, sizeof (*t));
 		  sw_if_index1 = vnet_buffer (b1)->sw_if_index[VLIB_RX];
 		  t->sw_if_index = sw_if_index1;
 		  t->next_index = next1;
 		  t->buffer_index = bi1;
 		}
 	    }

 	  /* verify speculative enqueues, maybe switch current next frame */
 	  vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
 					   to_next, n_left_to_next,
 					   bi0, bi1, next0, next1);
 	}

       while (n_left_from > 0 && n_left_to_next > 0)
 	{
 	  u32 bi0;
 	  vlib_buffer_t *b0;
 	  u32 next0;
 	  u32 sw_if_index0;

 	  /* speculatively enqueue b0 to the current next frame */
 	  bi0 = from[0];
 	  to_next[0] = bi0;
 	  from += 1;
 	  to_next += 1;
 	  n_left_from -= 1;
 	  n_left_to_next -= 1;

 	  b0 = vlib_get_buffer (vm, bi0);

 	  next0 = vnet_buffer (b0)->handoff.next_index;

 	  if (PREDICT_FALSE (vm->trace_main.trace_active_hint))
 	    {
 	      if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
 		{
 		  vlib_trace_buffer (vm, node, next0, b0,	/* follow_chain */
 				     0);
 		  handoff_dispatch_trace_t *t =
 		    vlib_add_trace (vm, node, b0, sizeof (*t));
 		  sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
 		  t->sw_if_index = sw_if_index0;
 		  t->next_index = next0;
 		  t->buffer_index = bi0;
 		}
 	    }

 	  /* verify speculative enqueue, maybe switch current next frame */
 	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
 					   to_next, n_left_to_next,
 					   bi0, next0);
 	}

       vlib_put_next_frame (vm, node, next_index, n_left_to_next);
     }

   return frame->n_vectors;
 }

 /* *INDENT-OFF* */
 VLIB_REGISTER_NODE (handoff_dispatch_node) = {
   .function = handoff_dispatch_node_fn,
   .name = "handoff-dispatch",
   .vector_size = sizeof (u32),
   .format_trace = format_handoff_dispatch_trace,
   .type = VLIB_NODE_TYPE_INTERNAL,
   .flags = VLIB_NODE_FLAG_IS_HANDOFF,

   .n_errors = ARRAY_LEN(handoff_dispatch_error_strings),
   .error_strings = handoff_dispatch_error_strings,

   .n_next_nodes = HANDOFF_DISPATCH_N_NEXT,

   .next_nodes = {
         [HANDOFF_DISPATCH_NEXT_DROP] = "error-drop",
         [HANDOFF_DISPATCH_NEXT_ETHERNET_INPUT] = "ethernet-input",
         [HANDOFF_DISPATCH_NEXT_IP4_INPUT] = "ip4-input-no-checksum",
         [HANDOFF_DISPATCH_NEXT_IP6_INPUT] = "ip6-input",
         [HANDOFF_DISPATCH_NEXT_MPLS_INPUT] = "mpls-input",
   },
 };

 VLIB_NODE_FUNCTION_MULTIARCH (handoff_dispatch_node, handoff_dispatch_node_fn)
 /* *INDENT-ON* */

 clib_error_t *
 handoff_init (vlib_main_t * vm)
 {
   handoff_main_t *hm = &handoff_main;
   vlib_thread_main_t *tm = vlib_get_thread_main ();
   clib_error_t *error;
   uword *p;

   if ((error = vlib_call_init_function (vm, threads_init)))
     return error;

   vlib_thread_registration_t *tr;
   /* Only the standard vnet worker threads are supported */
   p = hash_get_mem (tm->thread_registrations_by_name, "workers");
   if (p)
     {
       tr = (vlib_thread_registration_t *) p[0];
       if (tr)
 	{
 	  hm->num_workers = tr->count;
 	  hm->first_worker_index = tr->first_index;
 	}
     }

   hm->hash_fn = eth_get_key;

   hm->vlib_main = vm;
   hm->vnet_main = &vnet_main;

   hm->frame_queue_index = ~0;

   return 0;
 }

 VLIB_INIT_FUNCTION (handoff_init);

 /*
  * fd.io coding-style-patch-verification: ON
  *
  * Local Variables:
  * eval: (c-set-style "gnu")
  * End:
  */

	/*
	* Copyright (c) 2016 Cisco and/or its affiliates.
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at:
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include <vnet/vnet.h>
	#include <vppinfra/xxhash.h>
	#include <vlib/threads.h>
	#include <vnet/handoff.h>
	#include <vnet/feature/feature.h>

	typedef struct
	{
	uword *workers_bitmap;
	u32 *workers;
	} per_inteface_handoff_data_t;

	typedef struct
	{
	u32 cached_next_index;
	u32 num_workers;
	u32 first_worker_index;

	per_inteface_handoff_data_t *if_data;

	/* Worker handoff index */
	u32 frame_queue_index;

	/* convenience variables */
	vlib_main_t *vlib_main;
	vnet_main_t *vnet_main;

	u64 (hash_fn) (ethernet_header_t );
	} handoff_main_t;

	handoff_main_t handoff_main;
	vlib_node_registration_t handoff_dispatch_node;

	typedef struct
	{
	u32 sw_if_index;
	u32 next_worker_index;
	u32 buffer_index;
	} worker_handoff_trace_t;

	/* packet trace format function */
	static u8 *
	format_worker_handoff_trace (u8 * s, va_list * args)
	{
	CLIB_UNUSED (vlib_main_t * vm) = va_arg (args, vlib_main_t );
	CLIB_UNUSED (vlib_node_t * node) = va_arg (args, vlib_node_t );
	worker_handoff_trace_t t = va_arg (args, worker_handoff_trace_t *);

	s =
	format (s, "worker-handoff: sw_if_index %d, next_worker %d, buffer 0x%x",
	t->sw_if_index, t->next_worker_index, t->buffer_index);
	return s;
	}

	vlib_node_registration_t handoff_node;

	static uword
	worker_handoff_node_fn (vlib_main_t * vm,
	vlib_node_runtime_t * node, vlib_frame_t * frame)
	{
	handoff_main_t *hm = &handoff_main;
	vlib_thread_main_t *tm = vlib_get_thread_main ();
	u32 n_left_from, *from;
	static __thread vlib_frame_queue_elt_t **handoff_queue_elt_by_worker_index;
	static __thread vlib_frame_queue_t **congested_handoff_queue_by_worker_index
	= 0;
	vlib_frame_queue_elt_t *hf = 0;
	int i;
	u32 n_left_to_next_worker = 0, *to_next_worker = 0;
	u32 next_worker_index = 0;
	u32 current_worker_index = ~0;

	if (PREDICT_FALSE (handoff_queue_elt_by_worker_index == 0))
	{
	vec_validate (handoff_queue_elt_by_worker_index, tm->n_vlib_mains - 1);

	vec_validate_init_empty (congested_handoff_queue_by_worker_index,
	hm->first_worker_index + hm->num_workers - 1,
	(vlib_frame_queue_t *) (~0));
	}

	from = vlib_frame_vector_args (frame);
	n_left_from = frame->n_vectors;

	while (n_left_from > 0)
	{
	u32 bi0;
	vlib_buffer_t *b0;
	u32 sw_if_index0;
	u32 hash;
	u64 hash_key;
	per_inteface_handoff_data_t *ihd0;
	u32 index0;

	bi0 = from[0];
	from += 1;
	n_left_from -= 1;

	b0 = vlib_get_buffer (vm, bi0);
	sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
	ASSERT (hm->if_data);
	ihd0 = vec_elt_at_index (hm->if_data, sw_if_index0);

	next_worker_index = hm->first_worker_index;

	/*
	* Force unknown traffic onto worker 0,
	* and into ethernet-input. $$$$ add more hashes.
	*/

	/* Compute ingress LB hash */
	hash_key = hm->hash_fn ((ethernet_header_t *) b0->data);
	hash = (u32) clib_xxhash (hash_key);

	/* if input node did not specify next index, then packet
	should go to eternet-input */
	if (PREDICT_FALSE ((b0->flags & VNET_BUFFER_F_HANDOFF_NEXT_VALID) == 0))
	vnet_buffer (b0)->handoff.next_index =
	HANDOFF_DISPATCH_NEXT_ETHERNET_INPUT;
	else if (vnet_buffer (b0)->handoff.next_index ==
	HANDOFF_DISPATCH_NEXT_IP4_INPUT
	\|\| vnet_buffer (b0)->handoff.next_index ==
	HANDOFF_DISPATCH_NEXT_IP6_INPUT
	\|\| vnet_buffer (b0)->handoff.next_index ==
	HANDOFF_DISPATCH_NEXT_MPLS_INPUT)
	vlib_buffer_advance (b0, (sizeof (ethernet_header_t)));

	if (PREDICT_TRUE (is_pow2 (vec_len (ihd0->workers))))
	index0 = hash & (vec_len (ihd0->workers) - 1);
	else
	index0 = hash % vec_len (ihd0->workers);

	next_worker_index += ihd0->workers[index0];

	if (next_worker_index != current_worker_index)
	{
	if (hf)
	hf->n_vectors = VLIB_FRAME_SIZE - n_left_to_next_worker;

	hf = vlib_get_worker_handoff_queue_elt (hm->frame_queue_index,
	next_worker_index,
	handoff_queue_elt_by_worker_index);

	n_left_to_next_worker = VLIB_FRAME_SIZE - hf->n_vectors;
	to_next_worker = &hf->buffer_index[hf->n_vectors];
	current_worker_index = next_worker_index;
	}

	/* enqueue to correct worker thread */
	to_next_worker[0] = bi0;
	to_next_worker++;
	n_left_to_next_worker--;

	if (n_left_to_next_worker == 0)
	{
	hf->n_vectors = VLIB_FRAME_SIZE;
	vlib_put_frame_queue_elt (hf);
	current_worker_index = ~0;
	handoff_queue_elt_by_worker_index[next_worker_index] = 0;
	hf = 0;
	}

	if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
	&& (b0->flags & VLIB_BUFFER_IS_TRACED)))
	{
	worker_handoff_trace_t *t =
	vlib_add_trace (vm, node, b0, sizeof (*t));
	t->sw_if_index = sw_if_index0;
	t->next_worker_index = next_worker_index - hm->first_worker_index;
	t->buffer_index = bi0;
	}

	}

	if (hf)
	hf->n_vectors = VLIB_FRAME_SIZE - n_left_to_next_worker;

	/* Ship frames to the worker nodes */
	for (i = 0; i < vec_len (handoff_queue_elt_by_worker_index); i++)
	{
	if (handoff_queue_elt_by_worker_index[i])
	{
	hf = handoff_queue_elt_by_worker_index[i];
	/*
	* It works better to let the handoff node
	* rate-adapt, always ship the handoff queue element.
	*/
	if (1 \|\| hf->n_vectors == hf->last_n_vectors)
	{
	vlib_put_frame_queue_elt (hf);
	handoff_queue_elt_by_worker_index[i] = 0;
	}
	else
	hf->last_n_vectors = hf->n_vectors;
	}
	congested_handoff_queue_by_worker_index[i] =
	(vlib_frame_queue_t *) (~0);
	}
	hf = 0;
	current_worker_index = ~0;
	return frame->n_vectors;
	}

	/* INDENT-OFF */
	VLIB_REGISTER_NODE (worker_handoff_node) = {
	.function = worker_handoff_node_fn,
	.name = "worker-handoff",
	.vector_size = sizeof (u32),
	.format_trace = format_worker_handoff_trace,
	.type = VLIB_NODE_TYPE_INTERNAL,

	.n_next_nodes = 1,
	.next_nodes = {
	[0] = "error-drop",
	},
	};

	VLIB_NODE_FUNCTION_MULTIARCH (worker_handoff_node, worker_handoff_node_fn)
	/* INDENT-ON */

	int
	interface_handoff_enable_disable (vlib_main_t * vm, u32 sw_if_index,
	uword * bitmap, int enable_disable)
	{
	handoff_main_t *hm = &handoff_main;
	vnet_sw_interface_t *sw;
	vnet_main_t *vnm = vnet_get_main ();
	per_inteface_handoff_data_t *d;
	int i, rv = 0;

	if (pool_is_free_index (vnm->interface_main.sw_interfaces, sw_if_index))
	return VNET_API_ERROR_INVALID_SW_IF_INDEX;

	sw = vnet_get_sw_interface (vnm, sw_if_index);
	if (sw->type != VNET_SW_INTERFACE_TYPE_HARDWARE)
	return VNET_API_ERROR_INVALID_SW_IF_INDEX;

	if (clib_bitmap_last_set (bitmap) >= hm->num_workers)
	return VNET_API_ERROR_INVALID_WORKER;

	if (hm->frame_queue_index == ~0)
	hm->frame_queue_index =
	vlib_frame_queue_main_init (handoff_dispatch_node.index, 0);

	vec_validate (hm->if_data, sw_if_index);
	d = vec_elt_at_index (hm->if_data, sw_if_index);

	vec_free (d->workers);
	vec_free (d->workers_bitmap);

	if (enable_disable)
	{
	d->workers_bitmap = bitmap;
	/* INDENT-OFF */
	clib_bitmap_foreach (i, bitmap,
	({
	vec_add1(d->workers, i);
	}));
	/* INDENT-ON */
	}

	vnet_feature_enable_disable ("device-input", "worker-handoff",
	sw_if_index, enable_disable, 0, 0);
	return rv;
	}

	static clib_error_t *
	set_interface_handoff_command_fn (vlib_main_t * vm,
	unformat_input_t * input,
	vlib_cli_command_t * cmd)
	{
	handoff_main_t *hm = &handoff_main;
	u32 sw_if_index = ~0;
	int enable_disable = 1;
	uword *bitmap = 0;
	u32 sym = ~0;

	int rv = 0;

	while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
	{
	if (unformat (input, "disable"))
	enable_disable = 0;
	else if (unformat (input, "workers %U", unformat_bitmap_list, &bitmap))
	;
	else if (unformat (input, "%U", unformat_vnet_sw_interface,
	vnet_get_main (), &sw_if_index))
	;
	else if (unformat (input, "symmetrical"))
	sym = 1;
	else if (unformat (input, "asymmetrical"))
	sym = 0;
	else
	break;
	}

	if (sw_if_index == ~0)
	return clib_error_return (0, "Please specify an interface...");

	if (bitmap == 0)
	return clib_error_return (0, "Please specify list of workers...");

	rv =
	interface_handoff_enable_disable (vm, sw_if_index, bitmap,
	enable_disable);

	switch (rv)
	{
	case 0:
	break;

	case VNET_API_ERROR_INVALID_SW_IF_INDEX:
	return clib_error_return (0, "Invalid interface");
	break;

	case VNET_API_ERROR_INVALID_WORKER:
	return clib_error_return (0, "Invalid worker(s)");
	break;

	case VNET_API_ERROR_UNIMPLEMENTED:
	return clib_error_return (0,
	"Device driver doesn't support redirection");
	break;

	default:
	return clib_error_return (0, "unknown return value %d", rv);
	}

	if (sym == 1)
	hm->hash_fn = eth_get_sym_key;
	else if (sym == 0)
	hm->hash_fn = eth_get_key;

	return 0;
	}

	/* INDENT-OFF */
	VLIB_CLI_COMMAND (set_interface_handoff_command, static) = {
	.path = "set interface handoff",
	.short_help =
	"set interface handoff <interface-name> workers <workers-list> [symmetrical\|asymmetrical]",
	.function = set_interface_handoff_command_fn,
	};
	/* INDENT-ON */

	typedef struct
	{
	u32 buffer_index;
	u32 next_index;
	u32 sw_if_index;
	} handoff_dispatch_trace_t;

	/* packet trace format function */
	static u8 *
	format_handoff_dispatch_trace (u8 * s, va_list * args)
	{
	CLIB_UNUSED (vlib_main_t * vm) = va_arg (args, vlib_main_t );
	CLIB_UNUSED (vlib_node_t * node) = va_arg (args, vlib_node_t );
	handoff_dispatch_trace_t t = va_arg (args, handoff_dispatch_trace_t *);

	s = format (s, "handoff-dispatch: sw_if_index %d next_index %d buffer 0x%x",
	t->sw_if_index, t->next_index, t->buffer_index);
	return s;
	}

	#define foreach_handoff_dispatch_error \
	_(EXAMPLE, "example packets")

	typedef enum
	{
	#define _(sym,str) HANDOFF_DISPATCH_ERROR_##sym,
	foreach_handoff_dispatch_error
	#undef _
	HANDOFF_DISPATCH_N_ERROR,
	} handoff_dispatch_error_t;

	static char *handoff_dispatch_error_strings[] = {
	#define _(sym,string) string,
	foreach_handoff_dispatch_error
	#undef _
	};

	static uword
	handoff_dispatch_node_fn (vlib_main_t * vm,
	vlib_node_runtime_t * node, vlib_frame_t * frame)
	{
	u32 n_left_from, from, to_next;
	handoff_dispatch_next_t next_index;

	from = vlib_frame_vector_args (frame);
	n_left_from = frame->n_vectors;
	next_index = node->cached_next_index;

	while (n_left_from > 0)
	{
	u32 n_left_to_next;

	vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);

	while (n_left_from >= 4 && n_left_to_next >= 2)
	{
	u32 bi0, bi1;
	vlib_buffer_t b0, b1;
	u32 next0, next1;
	u32 sw_if_index0, sw_if_index1;

	/* Prefetch next iteration. */
	{
	vlib_buffer_t p2, p3;

	p2 = vlib_get_buffer (vm, from[2]);
	p3 = vlib_get_buffer (vm, from[3]);

	vlib_prefetch_buffer_header (p2, LOAD);
	vlib_prefetch_buffer_header (p3, LOAD);
	}

	/* speculatively enqueue b0 and b1 to the current next frame */
	to_next[0] = bi0 = from[0];
	to_next[1] = bi1 = from[1];
	from += 2;
	to_next += 2;
	n_left_from -= 2;
	n_left_to_next -= 2;

	b0 = vlib_get_buffer (vm, bi0);
	b1 = vlib_get_buffer (vm, bi1);

	next0 = vnet_buffer (b0)->handoff.next_index;
	next1 = vnet_buffer (b1)->handoff.next_index;

	if (PREDICT_FALSE (vm->trace_main.trace_active_hint))
	{
	if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
	{
	vlib_trace_buffer (vm, node, next0, b0, /* follow_chain */
	0);
	handoff_dispatch_trace_t *t =
	vlib_add_trace (vm, node, b0, sizeof (*t));
	sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
	t->sw_if_index = sw_if_index0;
	t->next_index = next0;
	t->buffer_index = bi0;
	}
	if (PREDICT_FALSE (b1->flags & VLIB_BUFFER_IS_TRACED))
	{
	vlib_trace_buffer (vm, node, next1, b1, /* follow_chain */
	0);
	handoff_dispatch_trace_t *t =
	vlib_add_trace (vm, node, b1, sizeof (*t));
	sw_if_index1 = vnet_buffer (b1)->sw_if_index[VLIB_RX];
	t->sw_if_index = sw_if_index1;
	t->next_index = next1;
	t->buffer_index = bi1;
	}
	}

	/* verify speculative enqueues, maybe switch current next frame */
	vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
	to_next, n_left_to_next,
	bi0, bi1, next0, next1);
	}

	while (n_left_from > 0 && n_left_to_next > 0)
	{
	u32 bi0;
	vlib_buffer_t *b0;
	u32 next0;
	u32 sw_if_index0;

	/* speculatively enqueue b0 to the current next frame */
	bi0 = from[0];
	to_next[0] = bi0;
	from += 1;
	to_next += 1;
	n_left_from -= 1;
	n_left_to_next -= 1;

	b0 = vlib_get_buffer (vm, bi0);

	next0 = vnet_buffer (b0)->handoff.next_index;

	if (PREDICT_FALSE (vm->trace_main.trace_active_hint))
	{
	if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
	{
	vlib_trace_buffer (vm, node, next0, b0, /* follow_chain */
	0);
	handoff_dispatch_trace_t *t =
	vlib_add_trace (vm, node, b0, sizeof (*t));
	sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
	t->sw_if_index = sw_if_index0;
	t->next_index = next0;
	t->buffer_index = bi0;
	}
	}

	/* verify speculative enqueue, maybe switch current next frame */
	vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
	to_next, n_left_to_next,
	bi0, next0);
	}

	vlib_put_next_frame (vm, node, next_index, n_left_to_next);
	}

	return frame->n_vectors;
	}

	/* INDENT-OFF */
	VLIB_REGISTER_NODE (handoff_dispatch_node) = {
	.function = handoff_dispatch_node_fn,
	.name = "handoff-dispatch",
	.vector_size = sizeof (u32),
	.format_trace = format_handoff_dispatch_trace,
	.type = VLIB_NODE_TYPE_INTERNAL,
	.flags = VLIB_NODE_FLAG_IS_HANDOFF,

	.n_errors = ARRAY_LEN(handoff_dispatch_error_strings),
	.error_strings = handoff_dispatch_error_strings,

	.n_next_nodes = HANDOFF_DISPATCH_N_NEXT,

	.next_nodes = {
	[HANDOFF_DISPATCH_NEXT_DROP] = "error-drop",
	[HANDOFF_DISPATCH_NEXT_ETHERNET_INPUT] = "ethernet-input",
	[HANDOFF_DISPATCH_NEXT_IP4_INPUT] = "ip4-input-no-checksum",
	[HANDOFF_DISPATCH_NEXT_IP6_INPUT] = "ip6-input",
	[HANDOFF_DISPATCH_NEXT_MPLS_INPUT] = "mpls-input",
	},
	};

	VLIB_NODE_FUNCTION_MULTIARCH (handoff_dispatch_node, handoff_dispatch_node_fn)
	/* INDENT-ON */

	clib_error_t *
	handoff_init (vlib_main_t * vm)
	{
	handoff_main_t *hm = &handoff_main;
	vlib_thread_main_t *tm = vlib_get_thread_main ();
	clib_error_t *error;
	uword *p;

	if ((error = vlib_call_init_function (vm, threads_init)))
	return error;

	vlib_thread_registration_t *tr;
	/* Only the standard vnet worker threads are supported */
	p = hash_get_mem (tm->thread_registrations_by_name, "workers");
	if (p)
	{
	tr = (vlib_thread_registration_t *) p[0];
	if (tr)
	{
	hm->num_workers = tr->count;
	hm->first_worker_index = tr->first_index;
	}
	}

	hm->hash_fn = eth_get_key;

	hm->vlib_main = vm;
	hm->vnet_main = &vnet_main;

	hm->frame_queue_index = ~0;

	return 0;
	}

	VLIB_INIT_FUNCTION (handoff_init);

	/*
	* fd.io coding-style-patch-verification: ON
	*
	* Local Variables:
	* eval: (c-set-style "gnu")
	* End:
	*/