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Allow to set latency_factor, bandwidth_factor and weight_S parameters of the network...
[simgrid.git] / src / surf / network.c
1 /*      $Id$     */
2
3 /* Copyright (c) 2004 Arnaud Legrand. All rights reserved.                  */
4
5 /* This program is free software; you can redistribute it and/or modify it
6  * under the terms of the license (GNU LGPL) which comes with this package. */
7
8 #include "network_private.h"
9 #include "xbt/log.h"
10 #include "xbt/str.h"
11
12 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(surf_network, surf,
13                                 "Logging specific to the SURF network module");
14
15 surf_model_t surf_network_model = NULL;
16 static lmm_system_t network_maxmin_system = NULL;
17 static void (*network_solve) (lmm_system_t) = NULL;
18
19 double sg_latency_factor = 1.0;    /* default value; can be set by model or from command line */
20 double sg_bandwidth_factor = 1.0;  /* default value; can be set by model or from command line */
21 double sg_weight_S_parameter = 0.0;/* default value; can be set by model or from command line */
22
23 double sg_tcp_gamma = 0.0;
24
25
26 static link_CM02_t net_link_new(char *name,
27                             double bw_initial,
28                             tmgr_trace_t bw_trace,
29                             double lat_initial,
30                             tmgr_trace_t lat_trace,
31                             e_surf_resource_state_t
32                             state_initial,
33                             tmgr_trace_t state_trace,
34                             e_surf_link_sharing_policy_t
35                             policy, xbt_dict_t properties)
36 {
37   link_CM02_t nw_link = (link_CM02_t)
38     surf_resource_lmm_new(sizeof(s_link_CM02_t),
39                           surf_network_model, name, properties,
40                           network_maxmin_system,
41                           sg_bandwidth_factor * bw_initial,
42                           history,
43                           state_initial, state_trace,
44                           bw_initial, bw_trace);
45
46   xbt_assert1(!xbt_dict_get_or_null(surf_network_model->resource_set, name),
47               "Link '%s' declared several times in the platform file.", name);
48
49   nw_link->lat_current = lat_initial;
50   if (lat_trace)
51     nw_link->lat_event =
52       tmgr_history_add_trace(history, lat_trace, 0.0, 0, nw_link);
53
54   if (policy == SURF_LINK_FATPIPE)
55     lmm_constraint_shared(nw_link->lmm_resource.constraint);
56
57   xbt_dict_set(surf_network_model->resource_set, name, nw_link,
58                surf_resource_free);
59
60   return nw_link;
61 }
62
63 static void net_parse_link_init(void)
64 {
65   char *name_link;
66   double bw_initial;
67   tmgr_trace_t bw_trace;
68   double lat_initial;
69   tmgr_trace_t lat_trace;
70   e_surf_resource_state_t state_initial_link = SURF_RESOURCE_ON;
71   e_surf_link_sharing_policy_t policy_initial_link = SURF_LINK_SHARED;
72   tmgr_trace_t state_trace;
73
74   name_link = xbt_strdup(A_surfxml_link_id);
75   surf_parse_get_double(&bw_initial, A_surfxml_link_bandwidth);
76   bw_trace = tmgr_trace_new(A_surfxml_link_bandwidth_file);
77   surf_parse_get_double(&lat_initial, A_surfxml_link_latency);
78   lat_trace = tmgr_trace_new(A_surfxml_link_latency_file);
79
80   xbt_assert0((A_surfxml_link_state == A_surfxml_link_state_ON)
81               || (A_surfxml_link_state ==
82                   A_surfxml_link_state_OFF), "Invalid state");
83   if (A_surfxml_link_state == A_surfxml_link_state_ON)
84     state_initial_link = SURF_RESOURCE_ON;
85   else if (A_surfxml_link_state == A_surfxml_link_state_OFF)
86     state_initial_link = SURF_RESOURCE_OFF;
87
88   if (A_surfxml_link_sharing_policy == A_surfxml_link_sharing_policy_SHARED)
89     policy_initial_link = SURF_LINK_SHARED;
90   else if (A_surfxml_link_sharing_policy ==
91            A_surfxml_link_sharing_policy_FATPIPE)
92     policy_initial_link = SURF_LINK_FATPIPE;
93
94   state_trace = tmgr_trace_new(A_surfxml_link_state_file);
95
96   net_link_new(name_link, bw_initial, bw_trace,
97            lat_initial, lat_trace, state_initial_link, state_trace,
98            policy_initial_link, xbt_dict_new());
99
100 }
101
102 static void net_add_traces(void)
103 {
104   xbt_dict_cursor_t cursor = NULL;
105   char *trace_name, *elm;
106
107   static int called = 0;
108   if (called)
109     return;
110   called = 1;
111
112   /* connect all traces relative to network */
113   xbt_dict_foreach(trace_connect_list_link_avail, cursor, trace_name, elm) {
114     tmgr_trace_t trace = xbt_dict_get_or_null(traces_set_list, trace_name);
115     link_CM02_t link =
116       xbt_dict_get_or_null(surf_network_model->resource_set, elm);
117
118     xbt_assert2(link, "Cannot connect trace %s to link %s: link undefined",
119                 trace_name, elm);
120     xbt_assert2(trace, "Cannot connect trace %s to link %s: trace undefined",
121                 trace_name, elm);
122
123     link->lmm_resource.state_event =
124       tmgr_history_add_trace(history, trace, 0.0, 0, link);
125   }
126
127   xbt_dict_foreach(trace_connect_list_bandwidth, cursor, trace_name, elm) {
128     tmgr_trace_t trace = xbt_dict_get_or_null(traces_set_list, trace_name);
129     link_CM02_t link =
130       xbt_dict_get_or_null(surf_network_model->resource_set, elm);
131
132     xbt_assert2(link, "Cannot connect trace %s to link %s: link undefined",
133                 trace_name, elm);
134     xbt_assert2(trace, "Cannot connect trace %s to link %s: trace undefined",
135                 trace_name, elm);
136
137     link->lmm_resource.power.event =
138       tmgr_history_add_trace(history, trace, 0.0, 0, link);
139   }
140
141   xbt_dict_foreach(trace_connect_list_latency, cursor, trace_name, elm) {
142     tmgr_trace_t trace = xbt_dict_get_or_null(traces_set_list, trace_name);
143     link_CM02_t link =
144       xbt_dict_get_or_null(surf_network_model->resource_set, elm);
145
146     xbt_assert2(link, "Cannot connect trace %s to link %s: link undefined",
147                 trace_name, elm);
148     xbt_assert2(trace, "Cannot connect trace %s to link %s: trace undefined",
149                 trace_name, elm);
150
151     link->lat_event = tmgr_history_add_trace(history, trace, 0.0, 0, link);
152   }
153 }
154
155 static void net_define_callbacks(const char *file)
156 {
157   /* Figuring out the network links */
158   surfxml_add_callback(STag_surfxml_link_cb_list, &net_parse_link_init);
159   surfxml_add_callback(ETag_surfxml_platform_cb_list, &net_add_traces);
160 }
161
162 static int net_resource_used(void *resource_id)
163 {
164   return lmm_constraint_used(network_maxmin_system,
165                              ((surf_resource_lmm_t) resource_id)->constraint);
166 }
167
168 static int net_action_unref(surf_action_t action)
169 {
170   action->refcount--;
171   if (!action->refcount) {
172     xbt_swag_remove(action, action->state_set);
173     if (((surf_action_network_CM02_t) action)->variable)
174       lmm_variable_free(network_maxmin_system,
175                         ((surf_action_network_CM02_t) action)->variable);
176     free(action);
177     return 1;
178   }
179   return 0;
180 }
181
182 static void net_action_cancel(surf_action_t action)
183 {
184   surf_network_model->action_state_set((surf_action_t) action,
185                                        SURF_ACTION_FAILED);
186   return;
187 }
188
189 static void net_action_recycle(surf_action_t action)
190 {
191   return;
192 }
193
194 static double net_action_get_remains(surf_action_t action)
195 {
196   return action->remains;
197 }
198
199 static double net_share_resources(double now)
200 {
201   s_surf_action_network_CM02_t s_action;
202   surf_action_network_CM02_t action = NULL;
203   xbt_swag_t running_actions = surf_network_model->states.running_action_set;
204   double min;
205
206   min = generic_maxmin_share_resources(running_actions,
207                                        xbt_swag_offset(s_action,
208                                                        variable),
209                                        network_maxmin_system, network_solve);
210
211 #define VARIABLE(action) (*((lmm_variable_t*)(((char *) (action)) + xbt_swag_offset(s_action, variable)  )))
212
213   xbt_swag_foreach(action, running_actions) {
214     if (action->latency > 0) {
215       if (min < 0)
216         min = action->latency;
217       else if (action->latency < min)
218         min = action->latency;
219     }
220   }
221
222   return min;
223 }
224
225 static void net_update_actions_state(double now, double delta)
226 {
227   double deltap = 0.0;
228   surf_action_network_CM02_t action = NULL;
229   surf_action_network_CM02_t next_action = NULL;
230   xbt_swag_t running_actions = surf_network_model->states.running_action_set;
231   /*
232      xbt_swag_t failed_actions =
233      surf_network_model->states.failed_action_set;
234    */
235
236   xbt_swag_foreach_safe(action, next_action, running_actions) {
237     deltap = delta;
238     if (action->latency > 0) {
239       if (action->latency > deltap) {
240         double_update(&(action->latency), deltap);
241         deltap = 0.0;
242       } else {
243         double_update(&(deltap), action->latency);
244         action->latency = 0.0;
245       }
246       if ((action->latency == 0.0) && !(action->suspended))
247         lmm_update_variable_weight(network_maxmin_system, action->variable,
248                                    action->weight);
249     }
250     double_update(&(action->generic_action.remains),
251                   lmm_variable_getvalue(action->variable) * deltap);
252     if (action->generic_action.max_duration != NO_MAX_DURATION)
253       double_update(&(action->generic_action.max_duration), delta);
254
255     if ((action->generic_action.remains <= 0) &&
256         (lmm_get_variable_weight(action->variable) > 0)) {
257       action->generic_action.finish = surf_get_clock();
258       surf_network_model->action_state_set((surf_action_t) action,
259                                            SURF_ACTION_DONE);
260     } else if ((action->generic_action.max_duration != NO_MAX_DURATION)
261                && (action->generic_action.max_duration <= 0)) {
262       action->generic_action.finish = surf_get_clock();
263       surf_network_model->action_state_set((surf_action_t) action,
264                                            SURF_ACTION_DONE);
265     }
266   }
267
268   return;
269 }
270
271 static void net_update_resource_state(void *id,
272                                   tmgr_trace_event_t event_type,
273                                   double value, double date)
274 {
275   link_CM02_t nw_link = id;
276   /*   printf("[" "%lg" "] Asking to update network card \"%s\" with value " */
277   /*     "%lg" " for event %p\n", surf_get_clock(), nw_link->name, */
278   /*     value, event_type); */
279
280   if (event_type == nw_link->lmm_resource.power.event) {
281     double delta =
282       sg_weight_S_parameter / value - sg_weight_S_parameter /
283       (nw_link->lmm_resource.power.peak * nw_link->lmm_resource.power.scale);
284     lmm_variable_t var = NULL;
285     lmm_element_t elem = NULL;
286     surf_action_network_CM02_t action = NULL;
287
288     nw_link->lmm_resource.power.peak = value;
289     lmm_update_constraint_bound(network_maxmin_system,
290                                 nw_link->lmm_resource.constraint,
291                                 sg_bandwidth_factor *
292                                 (nw_link->lmm_resource.power.peak *
293                                  nw_link->lmm_resource.power.scale));
294     if (sg_weight_S_parameter > 0) {
295       while ((var = lmm_get_var_from_cnst
296               (network_maxmin_system, nw_link->lmm_resource.constraint,
297                &elem))) {
298         action = lmm_variable_id(var);
299         action->weight += delta;
300         if (!(action->suspended))
301           lmm_update_variable_weight(network_maxmin_system, action->variable,
302                                      action->weight);
303       }
304     }
305     if (tmgr_trace_event_free(event_type))
306       nw_link->lmm_resource.power.event = NULL;
307   } else if (event_type == nw_link->lat_event) {
308     double delta = value - nw_link->lat_current;
309     lmm_variable_t var = NULL;
310     lmm_element_t elem = NULL;
311     surf_action_network_CM02_t action = NULL;
312
313     nw_link->lat_current = value;
314     while ((var = lmm_get_var_from_cnst
315             (network_maxmin_system, nw_link->lmm_resource.constraint,
316              &elem))) {
317       action = lmm_variable_id(var);
318       action->lat_current += delta;
319       action->weight += delta;
320       if (action->rate < 0)
321         lmm_update_variable_bound(network_maxmin_system, action->variable,
322                                   sg_tcp_gamma / (2.0 * action->lat_current));
323       else
324         lmm_update_variable_bound(network_maxmin_system, action->variable,
325                                   min(action->rate,
326                                       sg_tcp_gamma / (2.0 *
327                                                       action->lat_current)));
328       if (!(action->suspended))
329         lmm_update_variable_weight(network_maxmin_system, action->variable,
330                                    action->weight);
331
332     }
333     if (tmgr_trace_event_free(event_type))
334       nw_link->lat_event = NULL;
335   } else if (event_type == nw_link->lmm_resource.state_event) {
336     if (value > 0)
337       nw_link->lmm_resource.state_current = SURF_RESOURCE_ON;
338     else {
339       lmm_constraint_t cnst = nw_link->lmm_resource.constraint;
340       lmm_variable_t var = NULL;
341       lmm_element_t elem = NULL;
342
343       nw_link->lmm_resource.state_current = SURF_RESOURCE_OFF;
344       while ((var = lmm_get_var_from_cnst
345               (network_maxmin_system, cnst, &elem))) {
346         surf_action_t action = lmm_variable_id(var);
347
348         if (surf_action_state_get(action) == SURF_ACTION_RUNNING ||
349             surf_action_state_get(action) == SURF_ACTION_READY) {
350           action->finish = date;
351           surf_network_model->action_state_set(action, SURF_ACTION_FAILED);
352         }
353       }
354     }
355     if (tmgr_trace_event_free(event_type))
356       nw_link->lmm_resource.state_event = NULL;
357   } else {
358     CRITICAL0("Unknown event ! \n");
359     xbt_abort();
360   }
361
362   return;
363 }
364
365 static surf_action_t net_communicate(const char *src_name, const char *dst_name,
366                                  int src, int dst, double size, double rate)
367 {
368   surf_action_network_CM02_t action = NULL;
369   /* LARGE PLATFORMS HACK:
370      Add a link_CM02_t *link and a int link_nb to network_card_CM02_t. It will represent local links for this node
371      Use the cluster_id for ->id */
372   xbt_dynar_t route = used_routing->get_route(src, dst);
373   /* LARGE PLATFORMS HACK:
374      total_route_size = route_size + src->link_nb + dst->nb */
375   unsigned int i;
376
377   XBT_IN4("(%s,%s,%g,%g)", src_name, dst_name, size, rate);
378   /* LARGE PLATFORMS HACK:
379      assert on total_route_size */
380   xbt_assert2(xbt_dynar_length(route),
381               "You're trying to send data from %s to %s but there is no connection between these two hosts.",
382               src_name, dst_name);
383
384   link_CM02_t link;
385   int failed = 0;
386   xbt_dynar_foreach(route, i, link) {
387     if (link->lmm_resource.state_current == SURF_RESOURCE_OFF) {
388       failed = 1;
389       break;
390     }
391   }
392   action =
393     surf_action_new(sizeof(s_surf_action_network_CM02_t), size,
394                     surf_network_model, failed);
395
396   xbt_swag_insert(action, action->generic_action.state_set);
397   action->rate = rate;
398
399   action->latency = 0.0;
400   action->weight = 0.0;
401   xbt_dynar_foreach(route, i, link) {
402     action->latency += link->lat_current;
403     action->weight +=
404       link->lat_current +
405       sg_weight_S_parameter /
406       (link->lmm_resource.power.peak * link->lmm_resource.power.scale);
407   }
408   /* LARGE PLATFORMS HACK:
409      Add src->link and dst->link latencies */
410   action->lat_current = action->latency;
411   action->latency *= sg_latency_factor;
412
413   /* LARGE PLATFORMS HACK:
414      lmm_variable_new(..., total_route_size) */
415   if (action->latency > 0)
416     action->variable =
417       lmm_variable_new(network_maxmin_system, action, 0.0, -1.0,
418                        xbt_dynar_length(route));
419   else
420     action->variable =
421       lmm_variable_new(network_maxmin_system, action, 1.0, -1.0,
422                        xbt_dynar_length(route));
423
424   if (action->rate < 0) {
425     if (action->lat_current > 0)
426       lmm_update_variable_bound(network_maxmin_system, action->variable,
427                                 sg_tcp_gamma / (2.0 * action->lat_current));
428     else
429       lmm_update_variable_bound(network_maxmin_system, action->variable,
430                                 -1.0);
431   } else {
432     if (action->lat_current > 0)
433       lmm_update_variable_bound(network_maxmin_system, action->variable,
434                                 min(action->rate,
435                                     sg_tcp_gamma / (2.0 *
436                                                     action->lat_current)));
437     else
438       lmm_update_variable_bound(network_maxmin_system, action->variable,
439                                 action->rate);
440   }
441
442   xbt_dynar_foreach(route, i, link) {
443     lmm_expand(network_maxmin_system, link->lmm_resource.constraint,
444                action->variable, 1.0);
445   }
446   /* LARGE PLATFORMS HACK:
447      expand also with src->link and dst->link */
448
449   XBT_OUT;
450
451   return (surf_action_t) action;
452 }
453
454 static double net_get_link_bandwidth(const void *link)
455 {
456   surf_resource_lmm_t lmm = (surf_resource_lmm_t) link;
457   return lmm->power.peak * lmm->power.scale;
458 }
459
460 static double net_get_link_latency(const void *link)
461 {
462   return ((link_CM02_t) link)->lat_current;
463 }
464
465 static int net_link_shared(const void *link)
466 {
467   return lmm_constraint_is_shared(((surf_resource_lmm_t) link)->constraint);
468 }
469
470 static void net_action_suspend(surf_action_t action)
471 {
472   ((surf_action_network_CM02_t) action)->suspended = 1;
473   lmm_update_variable_weight(network_maxmin_system,
474                              ((surf_action_network_CM02_t) action)->variable,
475                              0.0);
476 }
477
478 static void net_action_resume(surf_action_t action)
479 {
480   if (((surf_action_network_CM02_t) action)->suspended) {
481     lmm_update_variable_weight(network_maxmin_system,
482                                ((surf_action_network_CM02_t)
483                                 action)->variable,
484                                ((surf_action_network_CM02_t) action)->weight);
485     ((surf_action_network_CM02_t) action)->suspended = 0;
486   }
487 }
488
489 static int net_action_is_suspended(surf_action_t action)
490 {
491   return ((surf_action_network_CM02_t) action)->suspended;
492 }
493
494 static void net_action_set_max_duration(surf_action_t action, double duration)
495 {
496   action->max_duration = duration;
497 }
498
499 static void net_finalize(void)
500 {
501   surf_model_exit(surf_network_model);
502   surf_network_model = NULL;
503
504   used_routing->finalize();
505   lmm_system_free(network_maxmin_system);
506   network_maxmin_system = NULL;
507 }
508
509 static void surf_network_model_init_internal(void)
510 {
511   surf_network_model = surf_model_init();
512
513   surf_network_model->name = "network";
514   surf_network_model->action_unref = net_action_unref;
515   surf_network_model->action_cancel = net_action_cancel;
516   surf_network_model->action_recycle = net_action_recycle;
517   surf_network_model->get_remains = net_action_get_remains;
518
519   surf_network_model->model_private->resource_used = net_resource_used;
520   surf_network_model->model_private->share_resources = net_share_resources;
521   surf_network_model->model_private->update_actions_state =
522     net_update_actions_state;
523   surf_network_model->model_private->update_resource_state =
524     net_update_resource_state;
525   surf_network_model->model_private->finalize = net_finalize;
526
527   surf_network_model->suspend = net_action_suspend;
528   surf_network_model->resume = net_action_resume;
529   surf_network_model->is_suspended = net_action_is_suspended;
530   surf_cpu_model->set_max_duration = net_action_set_max_duration;
531
532   surf_network_model->extension.network.communicate = net_communicate;
533   surf_network_model->extension.network.get_link_bandwidth =
534     net_get_link_bandwidth;
535   surf_network_model->extension.network.get_link_latency = net_get_link_latency;
536   surf_network_model->extension.network.link_shared = net_link_shared;
537
538   if (!network_maxmin_system)
539     network_maxmin_system = lmm_system_new();
540
541   routing_model_create(sizeof(link_CM02_t),
542                        net_link_new(xbt_strdup("__loopback__"),
543                                 498000000, NULL, 0.000015, NULL,
544                                 SURF_RESOURCE_ON, NULL, SURF_LINK_FATPIPE,
545                                 NULL));
546 }
547
548 /************************************************************************/
549 /* New model based on optimizations discussed during this thesis        */
550 /************************************************************************/
551 void surf_network_model_init_LegrandVelho(const char *filename)
552 {
553
554   if (surf_network_model)
555     return;
556   surf_network_model_init_internal();
557   net_define_callbacks(filename);
558   xbt_dynar_push(model_list, &surf_network_model);
559   network_solve = lmm_solve;
560
561   xbt_cfg_setdefault_double(_surf_cfg_set,"network/latency_factor",10.4);
562   xbt_cfg_setdefault_double(_surf_cfg_set,"network/bandwidth_factor", 0.92);
563   xbt_cfg_setdefault_double(_surf_cfg_set,"network/weight_S", 8775);
564
565   update_model_description(surf_network_model_description,
566                            "LV08", surf_network_model);
567 }
568
569 /***************************************************************************/
570 /* The nice TCP sharing model designed by Loris Marchal and Henri Casanova */
571 /***************************************************************************/
572 /* @TechReport{      rr-lip2002-40, */
573 /*   author        = {Henri Casanova and Loris Marchal}, */
574 /*   institution   = {LIP}, */
575 /*   title         = {A Network Model for Simulation of Grid Application}, */
576 /*   number        = {2002-40}, */
577 /*   month         = {oct}, */
578 /*   year          = {2002} */
579 /* } */
580 void surf_network_model_init_CM02(const char *filename)
581 {
582
583   if (surf_network_model)
584     return;
585   surf_network_model_init_internal();
586   net_define_callbacks(filename);
587   xbt_dynar_push(model_list, &surf_network_model);
588   network_solve = lmm_solve;
589
590   update_model_description(surf_network_model_description,
591                            "CM02", surf_network_model);
592 }
593
594 void surf_network_model_init_Reno(const char *filename)
595 {
596   if (surf_network_model)
597     return;
598   surf_network_model_init_internal();
599   net_define_callbacks(filename);
600
601   xbt_dynar_push(model_list, &surf_network_model);
602   lmm_set_default_protocol_function(func_reno_f, func_reno_fp, func_reno_fpi);
603   network_solve = lagrange_solve;
604
605   xbt_cfg_setdefault_double(_surf_cfg_set,"network/latency_factor", 10.4);
606   xbt_cfg_setdefault_double(_surf_cfg_set,"network/bandwidth_factor", 0.92);
607   xbt_cfg_setdefault_double(_surf_cfg_set,"network/weight_S", 8775);
608
609   update_model_description(surf_network_model_description,
610                            "Reno", surf_network_model);
611 }
612
613
614 void surf_network_model_init_Reno2(const char *filename)
615 {
616   if (surf_network_model)
617     return;
618   surf_network_model_init_internal();
619   net_define_callbacks(filename);
620
621   xbt_dynar_push(model_list, &surf_network_model);
622   lmm_set_default_protocol_function(func_reno2_f, func_reno2_fp,
623                                     func_reno2_fpi);
624   network_solve = lagrange_solve;
625
626   xbt_cfg_setdefault_double(_surf_cfg_set,"network/latency_factor", 10.4);
627   xbt_cfg_setdefault_double(_surf_cfg_set,"network/bandwidth_factor", 0.92);
628   xbt_cfg_setdefault_double(_surf_cfg_set,"network/weight_S_parameter", 8775);
629
630   update_model_description(surf_network_model_description,
631                            "Reno2", surf_network_model);
632 }
633
634 void surf_network_model_init_Vegas(const char *filename)
635 {
636   if (surf_network_model)
637     return;
638   surf_network_model_init_internal();
639   net_define_callbacks(filename);
640
641   xbt_dynar_push(model_list, &surf_network_model);
642   lmm_set_default_protocol_function(func_vegas_f, func_vegas_fp,
643                                     func_vegas_fpi);
644   network_solve = lagrange_solve;
645
646   xbt_cfg_setdefault_double(_surf_cfg_set,"network/latency_factor", 10.4);
647   xbt_cfg_setdefault_double(_surf_cfg_set,"network/bandwidth_factor", 0.92);
648   xbt_cfg_setdefault_double(_surf_cfg_set,"network/weight_S", 8775);
649
650   update_model_description(surf_network_model_description,
651                            "Vegas", surf_network_model);
652 }