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[simgrid.git] / src / simdag / sd_task.c
index 7546cc4..c55d588 100644 (file)
@@ -1,11 +1,11 @@
-/* Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011. The SimGrid Team.
+/* Copyright (c) 2006-2015. The SimGrid Team.
  * All rights reserved.                                                     */
 
 /* This program is free software; you can redistribute it and/or modify it
  * under the terms of the license (GNU LGPL) which comes with this package. */
 
 #include "private.h"
-#include "simdag/simdag.h"
+#include "simgrid/simdag.h"
 #include "xbt/sysdep.h"
 #include "xbt/dynar.h"
 #include "instr/instr_private.h"
@@ -55,8 +55,8 @@ void SD_task_recycle_f(void *t)
   /* scheduling parameters */
   task->workstation_nb = 0;
   task->workstation_list = NULL;
-  task->computation_amount = NULL;
-  task->communication_amount = NULL;
+  task->flops_amount = NULL;
+  task->bytes_amount = NULL;
   task->rate = -1;
 }
 
@@ -90,13 +90,139 @@ SD_task_t SD_task_create(const char *name, void *data, double amount)
 
   sd_global->task_number++;
 
-#ifdef HAVE_TRACING
   TRACE_sd_task_create(task);
-#endif
 
   return task;
 }
 
+static XBT_INLINE SD_task_t SD_task_create_sized(const char *name,
+                                                 void *data, double amount,
+                                                 int ws_count)
+{
+  SD_task_t task = SD_task_create(name, data, amount);
+  task->bytes_amount = xbt_new0(double, ws_count * ws_count);
+  task->flops_amount = xbt_new0(double, ws_count);
+  task->workstation_nb = ws_count;
+  task->workstation_list = xbt_new0(SD_workstation_t, ws_count);
+  return task;
+}
+
+/** @brief create a end-to-end communication task that can then be auto-scheduled
+ *
+ * Auto-scheduling mean that the task can be used with SD_task_schedulev(). This
+ * allows to specify the task costs at creation, and decouple them from the
+ * scheduling process where you just specify which resource should deliver the
+ * mandatory power.
+ *
+ * A end-to-end communication must be scheduled on 2 hosts, and the amount
+ * specified at creation is sent from hosts[0] to hosts[1].
+ */
+SD_task_t SD_task_create_comm_e2e(const char *name, void *data,
+                                  double amount)
+{
+  SD_task_t res = SD_task_create_sized(name, data, amount, 2);
+  res->bytes_amount[2] = amount;
+  res->kind = SD_TASK_COMM_E2E;
+
+  TRACE_category("COMM_E2E");
+  TRACE_sd_set_task_category(res, "COMM_E2E");
+
+  return res;
+}
+
+/** @brief create a sequential computation task that can then be auto-scheduled
+ *
+ * Auto-scheduling mean that the task can be used with SD_task_schedulev(). This
+ * allows to specify the task costs at creation, and decouple them from the
+ * scheduling process where you just specify which resource should deliver the
+ * mandatory power.
+ *
+ * A sequential computation must be scheduled on 1 host, and the amount
+ * specified at creation to be run on hosts[0].
+ *
+ * \param name the name of the task (can be \c NULL)
+ * \param data the user data you want to associate with the task (can be \c NULL)
+ * \param flops_amount amount of compute work to be done by the task
+ * \return the new SD_TASK_COMP_SEQ typed task
+ */
+SD_task_t SD_task_create_comp_seq(const char *name, void *data,
+                                  double flops_amount)
+{
+  SD_task_t res = SD_task_create_sized(name, data, flops_amount, 1);
+  res->flops_amount[0] = flops_amount;
+  res->kind = SD_TASK_COMP_SEQ;
+
+  TRACE_category("COMP_SEQ");
+  TRACE_sd_set_task_category(res, "COMP_SEQ");
+
+  return res;
+}
+
+/** @brief create a parallel computation task that can then be auto-scheduled
+ *
+ * Auto-scheduling mean that the task can be used with SD_task_schedulev(). This
+ * allows to specify the task costs at creation, and decouple them from the
+ * scheduling process where you just specify which resource should deliver the
+ * mandatory power.
+ *
+ * A parallel computation can be scheduled on any number of host.
+ * The underlying speedup model is Amdahl's law.
+ * To be auto-scheduled, \see SD_task_distribute_comp_amdahl has to be called
+ * first.
+ * \param name the name of the task (can be \c NULL)
+ * \param data the user data you want to associate with the task (can be \c NULL)
+ * \param flops_amount amount of compute work to be done by the task
+ * \param alpha purely serial fraction of the work to be done (in [0.;1.[)
+ * \return the new task
+ */
+SD_task_t SD_task_create_comp_par_amdahl(const char *name, void *data,
+                                  double flops_amount, double alpha)
+{
+  xbt_assert(alpha < 1. && alpha >= 0.,
+              "Invalid parameter: alpha must be in [0.;1.[");
+  
+  SD_task_t res = SD_task_create(name, data, flops_amount);
+  res->alpha = alpha;
+  res->kind = SD_TASK_COMP_PAR_AMDAHL;
+
+  TRACE_category("COMP_PAR_AMDAHL");
+  TRACE_sd_set_task_category(res, "COMP_PAR_AMDAHL");
+
+  return res;
+}
+
+/** @brief create a complex data redistribution task that can then be 
+ * auto-scheduled
+ *
+ * Auto-scheduling mean that the task can be used with SD_task_schedulev(). 
+ * This allows to specify the task costs at creation, and decouple them from 
+ * the scheduling process where you just specify which resource should 
+ * communicate. 
+ *
+ * A data redistribution can be scheduled on any number of host.
+ * The assumed distribution is a 1D block distribution. Each host owns the same
+ * share of the \see amount. 
+ * To be auto-scheduled, \see SD_task_distribute_comm_mxn_1d_block has to be 
+ * called first.
+ * \param name the name of the task (can be \c NULL)
+ * \param data the user data you want to associate with the task (can be
+ * \c NULL)
+ * \param amount amount of data to redistribute by the task
+ * \return the new task
+ */
+SD_task_t SD_task_create_comm_par_mxn_1d_block(const char *name, void *data,
+                                               double amount)
+{
+  SD_task_t res = SD_task_create(name, data, amount);
+  res->workstation_list=NULL;
+  res->kind = SD_TASK_COMM_PAR_MXN_1D_BLOCK;
+
+  TRACE_category("COMM_PAR_MXN_1D_BLOCK");
+  TRACE_sd_set_task_category(res, "COMM_PAR_MXN_1D_BLOCK");
+
+  return res;
+}
+
 /**
  * \brief Destroys a task.
  *
@@ -121,19 +247,17 @@ void SD_task_destroy(SD_task_t task)
   xbt_free(task->name);
 
   if (task->surf_action != NULL)
-    surf_workstation_model->action_unref(task->surf_action);
+       surf_action_unref(task->surf_action);
 
   xbt_free(task->workstation_list);
-  xbt_free(task->communication_amount);
-  xbt_free(task->computation_amount);
+  xbt_free(task->bytes_amount);
+  xbt_free(task->flops_amount);
+
+  TRACE_sd_task_destroy(task);
 
   xbt_mallocator_release(sd_global->task_mallocator,task);
   sd_global->task_number--;
 
-#ifdef HAVE_TRACING
-  TRACE_sd_task_destroy(task);
-#endif
-
   XBT_DEBUG("Task destroyed.");
 }
 
@@ -164,6 +288,32 @@ void SD_task_set_data(SD_task_t task, void *data)
   task->data = data;
 }
 
+/**
+ * \brief Sets the rate of a task
+ *
+ * This will change the network bandwidth a task can use. This rate
+ * cannot be dynamically changed. Once the task has started, this call
+ * is ineffective. This rate depends on both the nominal bandwidth on
+ * the route onto which the task is scheduled (\see
+ * SD_task_get_current_bandwidth) and the amount of data to transfer.
+ *
+ * To divide the nominal bandwidth by 2, the rate then has to be :
+ *    rate = bandwidth/(2*amount)
+ *
+ * \param task a \see SD_TASK_COMM_E2E task (end-to-end communication)
+ * \param rate the new rate you want to associate with this task.
+ */
+void SD_task_set_rate(SD_task_t task, double rate)
+{
+  xbt_assert(task->kind == SD_TASK_COMM_E2E,
+             "The rate can be modified for end-to-end communications only.");
+  if(task->start_time<0) {
+    task->rate = rate;
+  } else {
+    XBT_WARN("Task %p has started. Changing rate is ineffective.", task);
+  }
+}
+
 /**
  * \brief Returns the state of a task
  *
@@ -200,13 +350,11 @@ void __SD_task_set_state(SD_task_t task, e_SD_task_state_t new_state)
     break;
   case SD_RUNNING:
     task->state_set = sd_global->running_task_set;
-    task->start_time =
-        surf_workstation_model->action_get_start_time(task->surf_action);
+    task->start_time = surf_action_get_start_time(task->surf_action);
     break;
   case SD_DONE:
     task->state_set = sd_global->done_task_set;
-    task->finish_time =
-        surf_workstation_model->action_get_finish_time(task->surf_action);
+    task->finish_time = surf_action_get_finish_time(task->surf_action);
     task->remains = 0;
 #ifdef HAVE_JEDULE
     jedule_log_sd_event(task);
@@ -317,6 +465,40 @@ double SD_task_get_amount(SD_task_t task)
   return task->amount;
 }
 
+/**
+ * \brief Sets the total amount of work of a task
+ * For sequential typed tasks (COMP_SEQ and COMM_E2E), it also sets the
+ * appropriate values in the flops_amount and bytes_amount arrays
+ * respectively. Nothing more than modifying task->amount is done for paralle
+ * typed tasks (COMP_PAR_AMDAHL and COMM_PAR_MXN_1D_BLOCK) as the distribution
+ * of the amount of work is done at scheduling time.
+ *
+ * \param task a task
+ * \param amount the new amount of work to execute
+ */
+void SD_task_set_amount(SD_task_t task, double amount)
+{
+  task->amount = amount;
+  if (task->kind == SD_TASK_COMP_SEQ)
+    task->flops_amount[0] = amount;
+  if (task->kind == SD_TASK_COMM_E2E)
+    task->bytes_amount[2] = amount;
+}
+
+/**
+ * \brief Returns the alpha parameter of a SD_TASK_COMP_PAR_AMDAHL task
+ *
+ * \param task a parallel task assuming Amdahl's law as speedup model
+ * \return the alpha parameter (serial part of a task in percent) for this task
+ */
+double SD_task_get_alpha(SD_task_t task)
+{
+  xbt_assert(SD_task_get_kind(task) == SD_TASK_COMP_PAR_AMDAHL,
+     "Alpha parameter is not defined for this kink of task");
+  return task->alpha;
+}
+
+
 /**
  * \brief Returns the remaining amount work to do till the completion of a task
  *
@@ -327,7 +509,7 @@ double SD_task_get_amount(SD_task_t task)
 double SD_task_get_remaining_amount(SD_task_t task)
 {
   if (task->surf_action)
-    return surf_workstation_model->get_remains(task->surf_action);
+       return surf_action_get_remains(task->surf_action);
   else
     return task->remains;
 }
@@ -346,16 +528,16 @@ void SD_task_dump(SD_task_t task)
 
   XBT_INFO("Displaying task %s", SD_task_get_name(task));
   statename = bprintf("%s %s %s %s %s %s %s %s",
-                      (task->state & SD_NOT_SCHEDULED ? "not scheduled" :
+                      (task->state == SD_NOT_SCHEDULED ? "not scheduled" :
                        ""),
-                      (task->state & SD_SCHEDULABLE ? "schedulable" : ""),
-                      (task->state & SD_SCHEDULED ? "scheduled" : ""),
-                      (task->state & SD_RUNNABLE ? "runnable" :
+                      (task->state == SD_SCHEDULABLE ? "schedulable" : ""),
+                      (task->state == SD_SCHEDULED ? "scheduled" : ""),
+                      (task->state == SD_RUNNABLE ? "runnable" :
                        "not runnable"),
-                      (task->state & SD_IN_FIFO ? "in fifo" : ""),
-                      (task->state & SD_RUNNING ? "running" : ""),
-                      (task->state & SD_DONE ? "done" : ""),
-                      (task->state & SD_FAILED ? "failed" : ""));
+                      (task->state == SD_IN_FIFO ? "in fifo" : ""),
+                      (task->state == SD_RUNNING ? "running" : ""),
+                      (task->state == SD_DONE ? "done" : ""),
+                      (task->state == SD_FAILED ? "failed" : ""));
   XBT_INFO("  - state: %s", statename);
   free(statename);
 
@@ -367,19 +549,31 @@ void SD_task_dump(SD_task_t task)
     case SD_TASK_COMP_SEQ:
       XBT_INFO("  - kind: sequential computation");
       break;
+    case SD_TASK_COMP_PAR_AMDAHL:
+      XBT_INFO("  - kind: parallel computation following Amdahl's law");
+      break;
+    case SD_TASK_COMM_PAR_MXN_1D_BLOCK:
+      XBT_INFO("  - kind: MxN data redistribution assuming 1D block distribution");
+      break;
     default:
       XBT_INFO("  - (unknown kind %d)", task->kind);
     }
   }
+
+  if (task->category)
+    XBT_INFO("  - tracing category: %s", task->category);
+
   XBT_INFO("  - amount: %.0f", SD_task_get_amount(task));
+  if (task->kind == SD_TASK_COMP_PAR_AMDAHL)
+    XBT_INFO("  - alpha: %.2f", task->alpha);
   XBT_INFO("  - Dependencies to satisfy: %d", task->unsatisfied_dependencies);
-  if (xbt_dynar_length(task->tasks_before)) {
+  if (!xbt_dynar_is_empty(task->tasks_before)) {
     XBT_INFO("  - pre-dependencies:");
     xbt_dynar_foreach(task->tasks_before, counter, dependency) {
       XBT_INFO("    %s", SD_task_get_name(dependency->src));
     }
   }
-  if (xbt_dynar_length(task->tasks_after)) {
+  if (!xbt_dynar_is_empty(task->tasks_after)) {
     XBT_INFO("  - post-dependencies:");
     xbt_dynar_foreach(task->tasks_after, counter, dependency) {
       XBT_INFO("    %s", SD_task_get_name(dependency->dst));
@@ -395,9 +589,11 @@ void SD_task_dotty(SD_task_t task, void *out)
   fprintf(out, "  T%p [label=\"%.20s\"", task, task->name);
   switch (task->kind) {
   case SD_TASK_COMM_E2E:
+  case SD_TASK_COMM_PAR_MXN_1D_BLOCK:
     fprintf(out, ", shape=box");
     break;
   case SD_TASK_COMP_SEQ:
+  case SD_TASK_COMP_PAR_AMDAHL:
     fprintf(out, ", shape=circle");
     break;
   default:
@@ -413,8 +609,7 @@ void SD_task_dotty(SD_task_t task, void *out)
  */
 static void __SD_task_dependency_destroy(void *dependency)
 {
-  if (((SD_dependency_t) dependency)->name != NULL)
-    xbt_free(((SD_dependency_t) dependency)->name);
+  xbt_free(((SD_dependency_t)dependency)->name);
   xbt_free(dependency);
 }
 
@@ -434,9 +629,9 @@ void SD_task_dependency_add(const char *name, void *data, SD_task_t src,
                             SD_task_t dst)
 {
   xbt_dynar_t dynar;
-  int length;
+  unsigned long length;
   int found = 0;
-  int i;
+  unsigned long i;
   SD_dependency_t dependency;
 
   dynar = src->tasks_after;
@@ -448,9 +643,10 @@ void SD_task_dependency_add(const char *name, void *data, SD_task_t src,
            SD_task_get_name(src));
 
   if (!__SD_task_is_not_scheduled(src) && !__SD_task_is_schedulable(src)
-      && !__SD_task_is_scheduled_or_runnable(src))
+      && !__SD_task_is_scheduled_or_runnable(src) && !__SD_task_is_running(src))
     THROWF(arg_error, 0,
-           "Task '%s' must be SD_NOT_SCHEDULED, SD_SCHEDULABLE, SD_SCHEDULED or SD_RUNNABLE",
+           "Task '%s' must be SD_NOT_SCHEDULED, SD_SCHEDULABLE, SD_SCHEDULED or SD_RUNNABLE"
+     " or SD_RUNNING",
            SD_task_get_name(src));
 
   if (!__SD_task_is_not_scheduled(dst) && !__SD_task_is_schedulable(dst)
@@ -464,7 +660,7 @@ void SD_task_dependency_add(const char *name, void *data, SD_task_t src,
   for (i = 0; i < length && !found; i++) {
     xbt_dynar_get_cpy(dynar, i, &dependency);
     found = (dependency->dst == dst);
-    XBT_DEBUG("Dependency %d: dependency->dst = %s", i,
+    XBT_DEBUG("Dependency %lu: dependency->dst = %s", i,
            SD_task_get_name(dependency->dst));
   }
 
@@ -495,13 +691,27 @@ void SD_task_dependency_add(const char *name, void *data, SD_task_t src,
          SD_task_get_name(dst));
     __SD_task_set_state(dst, SD_SCHEDULED);
   }
+}
+/**
+ * \brief Returns the name given as input when dependency has been created..
+ *
+ * \param src a task
+ * \param dst a task depending on \a src
+ *
+ */
+const char *SD_task_dependency_get_name(SD_task_t src, SD_task_t dst){
+  unsigned int i;
+  SD_dependency_t dependency;
 
-  /*  __SD_print_dependencies(src);
-     __SD_print_dependencies(dst); */
+  xbt_dynar_foreach(src->tasks_after, i, dependency){
+    if (dependency->dst == dst)
+      return dependency->name;
+  }
+  return NULL;
 }
 
 /**
- * \brief Indacates whether there is a dependency between two tasks.
+ * \brief Indicates whether there is a dependency between two tasks.
  *
  * \param src a task
  * \param dst a task depending on \a src
@@ -544,9 +754,9 @@ void SD_task_dependency_remove(SD_task_t src, SD_task_t dst)
 {
 
   xbt_dynar_t dynar;
-  int length;
+  unsigned long length;
   int found = 0;
-  int i;
+  unsigned long i;
   SD_dependency_t dependency;
 
   /* remove the dependency from src->tasks_after */
@@ -615,9 +825,9 @@ void *SD_task_dependency_get_data(SD_task_t src, SD_task_t dst)
 {
 
   xbt_dynar_t dynar;
-  int length;
+  unsigned long length;
   int found = 0;
-  int i;
+  unsigned long i;
   SD_dependency_t dependency;
 
   dynar = src->tasks_after;
@@ -703,16 +913,16 @@ void SD_task_unwatch(SD_task_t task, e_SD_task_state_t state)
  * \param task the task to evaluate
  * \param workstation_nb number of workstations on which the task would be executed
  * \param workstation_list the workstations on which the task would be executed
- * \param computation_amount computation amount for each workstation
- * \param communication_amount communication amount between each pair of workstations
+ * \param flops_amount computation amount for each workstation
+ * \param bytes_amount communication amount between each pair of workstations
  * \see SD_schedule()
  */
 double SD_task_get_execution_time(SD_task_t task,
                                   int workstation_nb,
                                   const SD_workstation_t *
                                   workstation_list,
-                                  const double *computation_amount,
-                                  const double *communication_amount)
+                                  const double *flops_amount,
+                                  const double *bytes_amount)
 {
   double time, max_time = 0.0;
   int i, j;
@@ -722,17 +932,17 @@ double SD_task_get_execution_time(SD_task_t task,
 
   for (i = 0; i < workstation_nb; i++) {
     time = 0.0;
-    if (computation_amount != NULL)
+    if (flops_amount != NULL)
       time =
           SD_workstation_get_computation_time(workstation_list[i],
-                                              computation_amount[i]);
+                                              flops_amount[i]);
 
-    if (communication_amount != NULL)
+    if (bytes_amount != NULL)
       for (j = 0; j < workstation_nb; j++) {
         time +=
             SD_route_get_communication_time(workstation_list[i],
                                             workstation_list[j],
-                                            communication_amount[i *
+                                            bytes_amount[i *
                                                                  workstation_nb
                                                                  + j]);
       }
@@ -767,15 +977,15 @@ static XBT_INLINE void SD_task_do_schedule(SD_task_t task)
  * \param task the task you want to schedule
  * \param workstation_count number of workstations on which the task will be executed
  * \param workstation_list the workstations on which the task will be executed
- * \param computation_amount computation amount for each workstation
- * \param communication_amount communication amount between each pair of workstations
+ * \param flops_amount computation amount for each workstation
+ * \param bytes_amount communication amount between each pair of workstations
  * \param rate task execution speed rate
  * \see SD_task_unschedule()
  */
 void SD_task_schedule(SD_task_t task, int workstation_count,
                       const SD_workstation_t * workstation_list,
-                      const double *computation_amount,
-                      const double *communication_amount, double rate)
+                      const double *flops_amount,
+                      const double *bytes_amount, double rate)
 {
   int communication_nb;
   task->workstation_nb = 0;
@@ -785,25 +995,25 @@ void SD_task_schedule(SD_task_t task, int workstation_count,
   task->workstation_nb = workstation_count;
   task->rate = rate;
 
-  if (computation_amount) {
-    task->computation_amount = xbt_realloc(task->computation_amount,
+  if (flops_amount) {
+    task->flops_amount = xbt_realloc(task->flops_amount,
                                            sizeof(double) * workstation_count);
-    memcpy(task->computation_amount, computation_amount,
+    memcpy(task->flops_amount, flops_amount,
            sizeof(double) * workstation_count);
   } else {
-    xbt_free(task->computation_amount);
-    task->computation_amount = NULL;
+    xbt_free(task->flops_amount);
+    task->flops_amount = NULL;
   }
 
   communication_nb = workstation_count * workstation_count;
-  if (communication_amount) {
-    task->communication_amount = xbt_realloc(task->communication_amount,
+  if (bytes_amount) {
+    task->bytes_amount = xbt_realloc(task->bytes_amount,
                                              sizeof(double) * communication_nb);
-    memcpy(task->communication_amount, communication_amount,
+    memcpy(task->bytes_amount, bytes_amount,
            sizeof(double) * communication_nb);
   } else {
-    xbt_free(task->communication_amount);
-    task->communication_amount = NULL;
+    xbt_free(task->bytes_amount);
+    task->bytes_amount = NULL;
   }
 
   task->workstation_list =
@@ -836,11 +1046,16 @@ void SD_task_unschedule(SD_task_t task)
            SD_task_get_name(task));
 
   if (__SD_task_is_scheduled_or_runnable(task)  /* if the task is scheduled or runnable */
-      &&task->kind == SD_TASK_NOT_TYPED)        /* Don't free scheduling data for typed tasks */
+      && ((task->kind == SD_TASK_COMP_PAR_AMDAHL) ||
+          (task->kind == SD_TASK_COMM_PAR_MXN_1D_BLOCK))) { /* Don't free scheduling data for typed tasks */
     __SD_task_destroy_scheduling_data(task);
+    xbt_free(task->workstation_list);
+    task->workstation_list=NULL;
+    task->workstation_nb = 0;
+  }
 
   if (__SD_task_is_running(task))       /* the task should become SD_FAILED */
-    surf_workstation_model->action_cancel(task->surf_action);
+       surf_action_cancel(task->surf_action);
   else {
     if (task->unsatisfied_dependencies == 0)
       __SD_task_set_state(task, SD_SCHEDULABLE);
@@ -851,7 +1066,8 @@ void SD_task_unschedule(SD_task_t task)
   task->start_time = -1.0;
 }
 
-/* Destroys the data memorized by SD_task_schedule. Task state must be SD_SCHEDULED or SD_RUNNABLE.
+/* Destroys the data memorized by SD_task_schedule.
+ * Task state must be SD_SCHEDULED or SD_RUNNABLE.
  */
 static void __SD_task_destroy_scheduling_data(SD_task_t task)
 {
@@ -861,37 +1077,36 @@ static void __SD_task_destroy_scheduling_data(SD_task_t task)
            "Task '%s' must be SD_SCHEDULED, SD_RUNNABLE or SD_IN_FIFO",
            SD_task_get_name(task));
 
-  xbt_free(task->computation_amount);
-  xbt_free(task->communication_amount);
-  task->computation_amount = task->communication_amount = NULL;
+  xbt_free(task->flops_amount);
+  xbt_free(task->bytes_amount);
+  task->flops_amount = task->bytes_amount = NULL;
 }
 
-/* Runs a task. This function is directly called by __SD_task_try_to_run if the task
- * doesn't have to wait in fifos. Otherwise, it is called by __SD_task_just_done when
- * the task gets out of its fifos.
+/* Runs a task. This function is directly called by __SD_task_try_to_run if
+ * the task doesn't have to wait in FIFOs. Otherwise, it is called by
+ * __SD_task_just_done when the task gets out of its FIFOs.
  */
 void __SD_task_really_run(SD_task_t task)
 {
 
   int i;
-  void **surf_workstations;
+  sg_host_t *hosts;
 
   xbt_assert(__SD_task_is_runnable_or_in_fifo(task),
               "Task '%s' is not runnable or in a fifo! Task state: %d",
-              SD_task_get_name(task), SD_task_get_state(task));
+             SD_task_get_name(task), (int)SD_task_get_state(task));
   xbt_assert(task->workstation_list != NULL,
               "Task '%s': workstation_list is NULL!",
               SD_task_get_name(task));
 
-
-
   XBT_DEBUG("Really running task '%s'", SD_task_get_name(task));
+  int host_nb = task->workstation_nb;
 
   /* set this task as current task for the workstations in sequential mode */
-  for (i = 0; i < task->workstation_nb; i++) {
+  for (i = 0; i < host_nb; i++) {
     if (SD_workstation_get_access_mode(task->workstation_list[i]) ==
         SD_WORKSTATION_SEQUENTIAL_ACCESS) {
-      task->workstation_list[i]->current_task = task;
+       sg_host_sd(task->workstation_list[i])->current_task = task;
       xbt_assert(__SD_workstation_is_busy(task->workstation_list[i]),
                   "The workstation should be busy now");
     }
@@ -902,92 +1117,49 @@ void __SD_task_really_run(SD_task_t task)
 
   /* start the task */
 
-  /* we have to create a Surf workstation array instead of the SimDag workstation array */
-  surf_workstations = xbt_new(void *, task->workstation_nb);
+  /* Copy the elements of the task into the action */
+  hosts = xbt_new(sg_host_t, host_nb);
 
-  for (i = 0; i < task->workstation_nb; i++)
-    surf_workstations[i] = task->workstation_list[i]->surf_workstation;
+  for (i = 0; i < host_nb; i++)
+    hosts[i] =  task->workstation_list[i];
 
-  /* It's allowed to pass a NULL vector as cost to mean vector of 0.0 (easing user's life). Let's deal with it */
-#define cost_or_zero(array,pos) ((array)?(array)[pos]:0.0)
+  double *flops_amount = xbt_new0(double, host_nb);
+  double *bytes_amount = xbt_new0(double, host_nb * host_nb);
 
-  task->surf_action = NULL;
-  if ((task->workstation_nb == 1)
-      && (cost_or_zero(task->communication_amount, 0) == 0.0)) {
-    task->surf_action =
-        surf_workstation_model->extension.
-        workstation.execute(surf_workstations[0],
-                            cost_or_zero(task->computation_amount, 0));
-  } else if ((task->workstation_nb == 1)
-             && (cost_or_zero(task->computation_amount, 0) == 0.0)) {
-
-    task->surf_action =
-        surf_workstation_model->extension.
-        workstation.communicate(surf_workstations[0], surf_workstations[0],
-                                cost_or_zero(task->communication_amount,
-                                             0), task->rate);
-  } else if ((task->workstation_nb == 2)
-             && (cost_or_zero(task->computation_amount, 0) == 0.0)
-             && (cost_or_zero(task->computation_amount, 1) == 0.0)) {
-    int nb = 0;
-    double value = 0.0;
-
-    for (i = 0; i < task->workstation_nb * task->workstation_nb; i++) {
-      if (cost_or_zero(task->communication_amount, i) > 0.0) {
-        nb++;
-        value = cost_or_zero(task->communication_amount, i);
-      }
-    }
-    if (nb == 1) {
-      task->surf_action =
-          surf_workstation_model->extension.
-          workstation.communicate(surf_workstations[0],
-                                  surf_workstations[1], value, task->rate);
-    }
-  }
-#undef cost_or_zero
-
-  if (!task->surf_action) {
-    double *computation_amount = xbt_new(double, task->workstation_nb);
-    double *communication_amount = xbt_new(double, task->workstation_nb *
-                                           task->workstation_nb);
-
-    memcpy(computation_amount, task->computation_amount, sizeof(double) *
-           task->workstation_nb);
-    memcpy(communication_amount, task->communication_amount,
-           sizeof(double) * task->workstation_nb * task->workstation_nb);
-
-    task->surf_action =
-        surf_workstation_model->extension.
-        workstation.execute_parallel_task(task->workstation_nb,
-                                          surf_workstations,
-                                          computation_amount,
-                                          communication_amount,
-                                          task->amount, task->rate);
-  } else {
-    xbt_free(surf_workstations);
-  }
 
-  surf_workstation_model->action_data_set(task->surf_action, task);
+  if(task->flops_amount)
+    memcpy(flops_amount, task->flops_amount, sizeof(double) *
+           host_nb);
+  if(task->bytes_amount)
+    memcpy(bytes_amount, task->bytes_amount,
+           sizeof(double) * host_nb * host_nb);
+
+  task->surf_action = surf_host_model_execute_parallel_task((surf_host_model_t)surf_host_model,
+                                                                    host_nb,
+                                                                    hosts,
+                                                                    flops_amount,
+                                                                    bytes_amount,
+                                                                    task->rate);
+
+  surf_action_set_data(task->surf_action, task);
 
   XBT_DEBUG("surf_action = %p", task->surf_action);
 
-#ifdef HAVE_TRACING
   if (task->category)
     TRACE_surf_action(task->surf_action, task->category);
-#endif
 
   __SD_task_destroy_scheduling_data(task);      /* now the scheduling data are not useful anymore */
   __SD_task_set_state(task, SD_RUNNING);
   xbt_assert(__SD_task_is_running(task), "Bad state of task '%s': %d",
-              SD_task_get_name(task), SD_task_get_state(task));
+             SD_task_get_name(task), (int)SD_task_get_state(task));
 
 }
 
-/* Tries to run a task. This function is called by SD_simulate() when a scheduled task becomes SD_RUNNABLE
- * (ie when its dependencies are satisfied).
- * If one of the workstations where the task is scheduled on is busy (in sequential mode),
- * the task doesn't start.
+/* Tries to run a task. This function is called by SD_simulate() when a
+ * scheduled task becomes SD_RUNNABLE (i.e., when its dependencies are
+ * satisfied).
+ * If one of the workstations where the task is scheduled on is busy (in
+ * sequential mode), the task doesn't start.
  * Returns whether the task has started.
  */
 int __SD_task_try_to_run(SD_task_t task)
@@ -999,7 +1171,7 @@ int __SD_task_try_to_run(SD_task_t task)
 
   xbt_assert(__SD_task_is_runnable(task),
               "Task '%s' is not runnable! Task state: %d",
-              SD_task_get_name(task), SD_task_get_state(task));
+             SD_task_get_name(task), (int)SD_task_get_state(task));
 
 
   for (i = 0; i < task->workstation_nb; i++) {
@@ -1009,19 +1181,19 @@ int __SD_task_try_to_run(SD_task_t task)
 
   XBT_DEBUG("Task '%s' can start: %d", SD_task_get_name(task), can_start);
 
-  if (!can_start) {             /* if the task cannot start and is not in the fifos yet */
+  if (!can_start) {             /* if the task cannot start and is not in the FIFOs yet */
     for (i = 0; i < task->workstation_nb; i++) {
       workstation = task->workstation_list[i];
-      if (workstation->access_mode == SD_WORKSTATION_SEQUENTIAL_ACCESS) {
-        XBT_DEBUG("Pushing task '%s' in the fifo of workstation '%s'",
+      if (sg_host_sd(workstation)->access_mode == SD_WORKSTATION_SEQUENTIAL_ACCESS) {
+        XBT_DEBUG("Pushing task '%s' in the FIFO of workstation '%s'",
                SD_task_get_name(task),
                SD_workstation_get_name(workstation));
-        xbt_fifo_push(workstation->task_fifo, task);
+        xbt_fifo_push(sg_host_sd(workstation)->task_fifo, task);
       }
     }
     __SD_task_set_state(task, SD_IN_FIFO);
     xbt_assert(__SD_task_is_in_fifo(task), "Bad state of task '%s': %d",
-                SD_task_get_name(task), SD_task_get_state(task));
+               SD_task_get_name(task), (int)SD_task_get_state(task));
     XBT_DEBUG("Task '%s' state is now SD_IN_FIFO", SD_task_get_name(task));
   } else {
     __SD_task_really_run(task);
@@ -1032,7 +1204,7 @@ int __SD_task_try_to_run(SD_task_t task)
 
 /* This function is called by SD_simulate when a task is done.
  * It updates task->state and task->action and executes if necessary the tasks
- * which were waiting in fifos for the end of `task'
+ * which were waiting in FIFOs for the end of `task'
  */
 void __SD_task_just_done(SD_task_t task)
 {
@@ -1047,7 +1219,7 @@ void __SD_task_just_done(SD_task_t task)
 
   xbt_assert(__SD_task_is_running(task),
               "The task must be running! Task state: %d",
-              SD_task_get_state(task));
+              (int)SD_task_get_state(task));
   xbt_assert(task->workstation_list != NULL,
               "Task '%s': workstation_list is NULL!",
               SD_task_get_name(task));
@@ -1056,40 +1228,40 @@ void __SD_task_just_done(SD_task_t task)
   candidates = xbt_new(SD_task_t, 8);
 
   __SD_task_set_state(task, SD_DONE);
-  surf_workstation_model->action_unref(task->surf_action);
+  surf_action_unref(task->surf_action);
   task->surf_action = NULL;
 
   XBT_DEBUG("Looking for candidates");
 
   /* if the task was executed on sequential workstations,
-     maybe we can execute the next task of the fifo for each workstation */
+     maybe we can execute the next task of the FIFO for each workstation */
   for (i = 0; i < task->workstation_nb; i++) {
     workstation = task->workstation_list[i];
     XBT_DEBUG("Workstation '%s': access_mode = %d",
-           SD_workstation_get_name(workstation), workstation->access_mode);
-    if (workstation->access_mode == SD_WORKSTATION_SEQUENTIAL_ACCESS) {
-      xbt_assert(workstation->task_fifo != NULL,
-                  "Workstation '%s' has sequential access but no fifo!",
+              SD_workstation_get_name(workstation), (int)sg_host_sd(workstation)->access_mode);
+    if (sg_host_sd(workstation)->access_mode == SD_WORKSTATION_SEQUENTIAL_ACCESS) {
+      xbt_assert(sg_host_sd(workstation)->task_fifo != NULL,
+                  "Workstation '%s' has sequential access but no FIFO!",
                   SD_workstation_get_name(workstation));
-      xbt_assert(workstation->current_task =
+      xbt_assert(sg_host_sd(workstation)->current_task =
                   task, "Workstation '%s': current task should be '%s'",
                   SD_workstation_get_name(workstation),
                   SD_task_get_name(task));
 
       /* the task is over so we can release the workstation */
-      workstation->current_task = NULL;
+      sg_host_sd(workstation)->current_task = NULL;
 
-      XBT_DEBUG("Getting candidate in fifo");
+      XBT_DEBUG("Getting candidate in FIFO");
       candidate =
           xbt_fifo_get_item_content(xbt_fifo_get_first_item
-                                    (workstation->task_fifo));
+                                    (sg_host_sd(workstation)->task_fifo));
 
       if (candidate != NULL) {
         XBT_DEBUG("Candidate: '%s'", SD_task_get_name(candidate));
         xbt_assert(__SD_task_is_in_fifo(candidate),
                     "Bad state of candidate '%s': %d",
                     SD_task_get_name(candidate),
-                    SD_task_get_state(candidate));
+                    (int)SD_task_get_state(candidate));
       }
 
       XBT_DEBUG("Candidate in fifo: %p", candidate);
@@ -1097,9 +1269,10 @@ void __SD_task_just_done(SD_task_t task)
       /* if there was a task waiting for my place */
       if (candidate != NULL) {
         /* Unfortunately, we are not sure yet that we can execute the task now,
-           because the task can be waiting more deeply in some other workstation's fifos...
-           So we memorize all candidate tasks, and then we will check for each candidate
-           whether or not all its workstations are available. */
+           because the task can be waiting more deeply in some other
+           workstation's FIFOs ...
+           So we memorize all candidate tasks, and then we will check for each
+           candidate whether or not all its workstations are available. */
 
         /* realloc if necessary */
         if (candidate_nb == candidate_capacity) {
@@ -1128,17 +1301,17 @@ void __SD_task_just_done(SD_task_t task)
 
     xbt_assert(__SD_task_is_in_fifo(candidate),
                 "Bad state of candidate '%s': %d",
-                SD_task_get_name(candidate), SD_task_get_state(candidate));
+               SD_task_get_name(candidate), (int)SD_task_get_state(candidate));
 
     for (j = 0; j < candidate->workstation_nb && can_start; j++) {
       workstation = candidate->workstation_list[j];
 
       /* I can start on this workstation if the workstation is shared
-         or if I am the first task in the fifo */
-      can_start = workstation->access_mode == SD_WORKSTATION_SHARED_ACCESS
+         or if I am the first task in the FIFO */
+      can_start = sg_host_sd(workstation)->access_mode == SD_WORKSTATION_SHARED_ACCESS
           || candidate ==
           xbt_fifo_get_item_content(xbt_fifo_get_first_item
-                                    (workstation->task_fifo));
+                                    (sg_host_sd(workstation)->task_fifo));
     }
 
     XBT_DEBUG("Candidate '%s' can start: %d", SD_task_get_name(candidate),
@@ -1149,20 +1322,20 @@ void __SD_task_just_done(SD_task_t task)
       for (j = 0; j < candidate->workstation_nb && can_start; j++) {
         workstation = candidate->workstation_list[j];
 
-        /* update the fifo */
-        if (workstation->access_mode == SD_WORKSTATION_SEQUENTIAL_ACCESS) {
-          candidate = xbt_fifo_shift(workstation->task_fifo);   /* the return value is stored just for debugging */
-          XBT_DEBUG("Head of the fifo: '%s'",
+        /* update the FIFO */
+        if (sg_host_sd(workstation)->access_mode == SD_WORKSTATION_SEQUENTIAL_ACCESS) {
+          candidate = xbt_fifo_shift(sg_host_sd(workstation)->task_fifo);   /* the return value is stored just for debugging */
+          XBT_DEBUG("Head of the FIFO: '%s'",
                  (candidate !=
                   NULL) ? SD_task_get_name(candidate) : "NULL");
           xbt_assert(candidate == candidates[i],
-                      "Error in __SD_task_just_done: bad first task in the fifo");
+                      "Error in __SD_task_just_done: bad first task in the FIFO");
         }
       }                         /* for each workstation */
 
       /* finally execute the task */
       XBT_DEBUG("Task '%s' state: %d", SD_task_get_name(candidate),
-             SD_task_get_state(candidate));
+             (int)SD_task_get_state(candidate));
       __SD_task_really_run(candidate);
 
       XBT_DEBUG
@@ -1172,7 +1345,7 @@ void __SD_task_just_done(SD_task_t task)
       xbt_assert(__SD_task_is_running(candidate),
                   "Bad state of task '%s': %d",
                   SD_task_get_name(candidate),
-                  SD_task_get_state(candidate));
+                 (int)SD_task_get_state(candidate));
       XBT_DEBUG("Okay, the task is running.");
 
     }                           /* can start */
@@ -1182,19 +1355,21 @@ void __SD_task_just_done(SD_task_t task)
   xbt_free(candidates);
 }
 
-/* Remove all dependencies associated with a task. This function is called when the task is destroyed.
+/* 
+ * Remove all dependencies associated with a task. This function is called 
+ * when the task is destroyed.
  */
 static void __SD_task_remove_dependencies(SD_task_t task)
 {
   /* we must destroy the dependencies carefuly (with SD_dependency_remove)
      because each one is stored twice */
   SD_dependency_t dependency;
-  while (xbt_dynar_length(task->tasks_before) > 0) {
+  while (!xbt_dynar_is_empty(task->tasks_before)) {
     xbt_dynar_get_cpy(task->tasks_before, 0, &dependency);
     SD_task_dependency_remove(dependency->src, dependency->dst);
   }
 
-  while (xbt_dynar_length(task->tasks_after) > 0) {
+  while (!xbt_dynar_is_empty(task->tasks_after)) {
     xbt_dynar_get_cpy(task->tasks_after, 0, &dependency);
     SD_task_dependency_remove(dependency->src, dependency->dst);
   }
@@ -1211,8 +1386,7 @@ static void __SD_task_remove_dependencies(SD_task_t task)
 double SD_task_get_start_time(SD_task_t task)
 {
   if (task->surf_action)
-    return surf_workstation_model->
-        action_get_start_time(task->surf_action);
+    return surf_action_get_start_time(task->surf_action);
   else
     return task->start_time;
 }
@@ -1231,96 +1405,78 @@ double SD_task_get_start_time(SD_task_t task)
 double SD_task_get_finish_time(SD_task_t task)
 {
   if (task->surf_action)        /* should never happen as actions are destroyed right after their completion */
-    return surf_workstation_model->
-        action_get_finish_time(task->surf_action);
+    return surf_action_get_finish_time(task->surf_action);
   else
     return task->finish_time;
 }
-
-static XBT_INLINE SD_task_t SD_task_create_sized(const char *name,
-                                                 void *data, double amount,
-                                                 int ws_count)
-{
-  SD_task_t task = SD_task_create(name, data, amount);
-  task->communication_amount = xbt_new0(double, ws_count * ws_count);
-  task->computation_amount = xbt_new0(double, ws_count);
-  task->workstation_nb = ws_count;
-  task->workstation_list = xbt_new0(SD_workstation_t, ws_count);
-  return task;
-}
-
-/** @brief create a end-to-end communication task that can then be auto-scheduled
+/** @brief Blah
  *
- * Auto-scheduling mean that the task can be used with SD_task_schedulev(). This
- * allows to specify the task costs at creation, and decorelate them from the
- * scheduling process where you just specify which resource should deliver the
- * mandatory power.
- *
- * A end-to-end communication must be scheduled on 2 hosts, and the amount
- * specified at creation is sent from hosts[0] to hosts[1].
  */
-SD_task_t SD_task_create_comm_e2e(const char *name, void *data,
-                                  double amount)
+void SD_task_distribute_comp_amdahl(SD_task_t task, int ws_count)
 {
-  SD_task_t res = SD_task_create_sized(name, data, amount, 2);
-  res->communication_amount[2] = amount;
-  res->kind = SD_TASK_COMM_E2E;
-  return res;
-}
+  int i;
+  xbt_assert(task->kind == SD_TASK_COMP_PAR_AMDAHL,
+              "Task %s is not a SD_TASK_COMP_PAR_AMDAHL typed task."
+              "Cannot use this function.",
+              SD_task_get_name(task));  
+  task->flops_amount = xbt_new0(double, ws_count);
+  task->bytes_amount = xbt_new0(double, ws_count * ws_count);
+  xbt_free(task->workstation_list);
+  task->workstation_nb = ws_count;
+  task->workstation_list = xbt_new0(SD_workstation_t, ws_count);
+  
+  for(i=0;i<ws_count;i++){
+    task->flops_amount[i] = 
+      (task->alpha + (1 - task->alpha)/ws_count) * task->amount;
+  }
+} 
 
-/** @brief create a sequential computation task that can then be auto-scheduled
- *
- * Auto-scheduling mean that the task can be used with SD_task_schedulev(). This
- * allows to specify the task costs at creation, and decorelate them from the
- * scheduling process where you just specify which resource should deliver the
- * mandatory power.
- *
- * A sequential computation must be scheduled on 1 host, and the amount
- * specified at creation to be run on hosts[0].
- */
-SD_task_t SD_task_create_comp_seq(const char *name, void *data,
-                                  double amount)
-{
-  SD_task_t res = SD_task_create_sized(name, data, amount, 1);
-  res->computation_amount[0] = amount;
-  res->kind = SD_TASK_COMP_SEQ;
-  return res;
-}
 
 /** @brief Auto-schedules a task.
  *
  * Auto-scheduling mean that the task can be used with SD_task_schedulev(). This
- * allows to specify the task costs at creation, and decorelate them from the
+ * allows to specify the task costs at creation, and decouple them from the
  * scheduling process where you just specify which resource should deliver the
  * mandatory power.
  *
- * To be auto-schedulable, a task must be created with SD_task_create_comm_e2e() or
- * SD_task_create_comp_seq(). Check their definitions for the exact semantic of each
- * of them.
+ * To be auto-schedulable, a task must be created with SD_task_create_comm_e2e()
+ * or SD_task_create_comp_seq(). Check their definitions for the exact semantic
+ * of each of them.
  *
  * @todo
  * We should create tasks kind for the following categories:
  *  - Point to point communication (done)
  *  - Sequential computation       (done)
  *  - group communication (redistribution, several kinds)
- *  - parallel tasks with no internal communication (one kind per speedup model such as amdal)
- *  - idem+ internal communication. Task type not enough since we cannot store comm cost alongside to comp one)
+ *  - parallel tasks with no internal communication (one kind per speedup
+ *    model such as Amdahl)
+ *  - idem+ internal communication. Task type not enough since we cannot store
+ *    comm cost alongside to comp one)
  */
 void SD_task_schedulev(SD_task_t task, int count,
                        const SD_workstation_t * list)
 {
-  int i;
+  int i, j;
   SD_dependency_t dep;
   unsigned int cpt;
   xbt_assert(task->kind != 0,
               "Task %s is not typed. Cannot automatically schedule it.",
               SD_task_get_name(task));
   switch (task->kind) {
+  case SD_TASK_COMP_PAR_AMDAHL:
+    SD_task_distribute_comp_amdahl(task, count);
   case SD_TASK_COMM_E2E:
   case SD_TASK_COMP_SEQ:
-    xbt_assert(task->workstation_nb == count,"Got %d locations, but were expecting %d locations",count,task->workstation_nb);
+    xbt_assert(task->workstation_nb == count,
+               "Got %d locations, but were expecting %d locations",
+               count,task->workstation_nb);
     for (i = 0; i < count; i++)
       task->workstation_list[i] = list[i];
+    if (SD_task_get_kind(task)== SD_TASK_COMP_SEQ && !task->flops_amount){
+      /*This task has failed and is rescheduled. Reset the flops_amount*/
+      task->flops_amount = xbt_new0(double, 1);
+      task->flops_amount[0] = task->remains;
+    }
     SD_task_do_schedule(task);
     break;
   default:
@@ -1332,15 +1488,17 @@ void SD_task_schedulev(SD_task_t task, int count,
           SD_task_get_name(task),
           SD_workstation_get_name(task->workstation_list[0]),
           SD_workstation_get_name(task->workstation_list[1]),
-          task->communication_amount[2]);
+          task->bytes_amount[2]);
 
   }
-  /* Iterate over all childs and parent being COMM_E2E to say where I am located (and start them if runnable) */
+
+  /* Iterate over all children and parents being COMM_E2E to say where I am
+   * located (and start them if runnable) */
   if (task->kind == SD_TASK_COMP_SEQ) {
     XBT_VERB("Schedule computation task %s on %s. It costs %.f flops",
           SD_task_get_name(task),
           SD_workstation_get_name(task->workstation_list[0]),
-          task->computation_amount[0]);
+          task->flops_amount[0]);
 
     xbt_dynar_foreach(task->tasks_before, cpt, dep) {
       SD_task_t before = dep->src;
@@ -1356,7 +1514,7 @@ void SD_task_schedulev(SD_task_t task, int count,
                SD_task_get_name(before),
                SD_workstation_get_name(before->workstation_list[0]),
                SD_workstation_get_name(before->workstation_list[1]),
-               before->communication_amount[2]);
+               before->bytes_amount[2]);
         }
       }
     }
@@ -1364,7 +1522,6 @@ void SD_task_schedulev(SD_task_t task, int count,
       SD_task_t after = dep->dst;
       if (after->kind == SD_TASK_COMM_E2E) {
         after->workstation_list[0] = task->workstation_list[0];
-        //J-N : Why did you comment on these line (this comment add a bug I think)?
         if (after->workstation_list[1]
             && (__SD_task_is_not_scheduled(after)
                 || __SD_task_is_schedulable(after))) {
@@ -1374,12 +1531,150 @@ void SD_task_schedulev(SD_task_t task, int count,
                SD_task_get_name(after),
                SD_workstation_get_name(after->workstation_list[0]),
                SD_workstation_get_name(after->workstation_list[1]),
-               after->communication_amount[2]);
+               after->bytes_amount[2]);
 
         }
       }
     }
   }
+  /* Iterate over all children and parents being MXN_1D_BLOCK to say where I am
+   * located (and start them if runnable) */
+  if (task->kind == SD_TASK_COMP_PAR_AMDAHL) {
+    XBT_VERB("Schedule computation task %s on %d workstations. %.f flops"
+             " will be distributed following Amdahl's Law",
+          SD_task_get_name(task), task->workstation_nb,
+          task->flops_amount[0]);
+    xbt_dynar_foreach(task->tasks_before, cpt, dep) {
+      SD_task_t before = dep->src;
+      if (before->kind == SD_TASK_COMM_PAR_MXN_1D_BLOCK){
+        if (!before->workstation_list){
+          XBT_VERB("Sender side of Task %s is not scheduled yet",
+             SD_task_get_name(before));
+          before->workstation_list = xbt_new0(SD_workstation_t, count);
+          before->workstation_nb = count;
+          XBT_VERB("Fill the workstation list with list of Task '%s'",
+            SD_task_get_name(task));
+          for (i=0;i<count;i++)
+            before->workstation_list[i] = task->workstation_list[i];
+        } else {
+          XBT_VERB("Build communication matrix for task '%s'",
+             SD_task_get_name(before));
+          int src_nb, dst_nb;
+          double src_start, src_end, dst_start, dst_end;
+          src_nb = before->workstation_nb;
+          dst_nb = count;
+          before->workstation_list = (SD_workstation_t*) xbt_realloc(
+             before->workstation_list,
+             (before->workstation_nb+count)*sizeof(s_SD_workstation_t));
+          for(i=0; i<count; i++)
+            before->workstation_list[before->workstation_nb+i] =
+               task->workstation_list[i];
+
+          before->workstation_nb += count;
+          xbt_free(before->flops_amount);
+          xbt_free(before->bytes_amount);
+          before->flops_amount = xbt_new0(double,
+                                                before->workstation_nb);
+          before->bytes_amount = xbt_new0(double,
+                                                  before->workstation_nb*
+                                                  before->workstation_nb);
+
+          for(i=0;i<src_nb;i++){
+            src_start = i*before->amount/src_nb;
+            src_end = src_start + before->amount/src_nb;
+            for(j=0; j<dst_nb; j++){
+              dst_start = j*before->amount/dst_nb;
+              dst_end = dst_start + before->amount/dst_nb;
+              XBT_VERB("(%s->%s): (%.2f, %.2f)-> (%.2f, %.2f)",
+                  SD_workstation_get_name(before->workstation_list[i]),
+                  SD_workstation_get_name(before->workstation_list[src_nb+j]),
+                  src_start, src_end, dst_start, dst_end);
+              if ((src_end <= dst_start) || (dst_end <= src_start)) {
+                before->bytes_amount[i*(src_nb+dst_nb)+src_nb+j]=0.0;
+              } else {
+                before->bytes_amount[i*(src_nb+dst_nb)+src_nb+j] =
+                  MIN(src_end, dst_end) - MAX(src_start, dst_start);
+              }
+              XBT_VERB("==> %.2f",
+                 before->bytes_amount[i*(src_nb+dst_nb)+src_nb+j]);
+            }
+          }
+
+          if (__SD_task_is_schedulable(before) ||
+              __SD_task_is_not_scheduled(before)) {
+            SD_task_do_schedule(before);
+            XBT_VERB
+              ("Auto-Schedule redistribution task %s. Send %.f bytes from %d hosts to %d hosts.",
+                  SD_task_get_name(before),before->amount, src_nb, dst_nb);
+            }
+        }
+      }
+    }
+    xbt_dynar_foreach(task->tasks_after, cpt, dep) {
+      SD_task_t after = dep->dst;
+      if (after->kind == SD_TASK_COMM_PAR_MXN_1D_BLOCK){
+        if (!after->workstation_list){
+          XBT_VERB("Receiver side of Task '%s' is not scheduled yet",
+              SD_task_get_name(after));
+          after->workstation_list = xbt_new0(SD_workstation_t, count);
+          after->workstation_nb = count;
+          XBT_VERB("Fill the workstation list with list of Task '%s'",
+            SD_task_get_name(task));
+          for (i=0;i<count;i++)
+            after->workstation_list[i] = task->workstation_list[i];
+        } else {
+          int src_nb, dst_nb;
+          double src_start, src_end, dst_start, dst_end;
+          src_nb = count;
+          dst_nb = after->workstation_nb;
+          after->workstation_list = (SD_workstation_t*) xbt_realloc(
+            after->workstation_list,
+            (after->workstation_nb+count)*sizeof(s_SD_workstation_t));
+          for(i=after->workstation_nb - 1; i>=0; i--)
+            after->workstation_list[count+i] = after->workstation_list[i];
+          for(i=0; i<count; i++)
+            after->workstation_list[i] = task->workstation_list[i];
+
+          after->workstation_nb += count;
+
+          xbt_free(after->flops_amount);
+          xbt_free(after->bytes_amount);
+
+          after->flops_amount = xbt_new0(double, after->workstation_nb);
+          after->bytes_amount = xbt_new0(double,
+                                                 after->workstation_nb*
+                                                 after->workstation_nb);
+
+          for(i=0;i<src_nb;i++){
+            src_start = i*after->amount/src_nb;
+            src_end = src_start + after->amount/src_nb;
+            for(j=0; j<dst_nb; j++){
+              dst_start = j*after->amount/dst_nb;
+              dst_end = dst_start + after->amount/dst_nb;
+              XBT_VERB("(%d->%d): (%.2f, %.2f)-> (%.2f, %.2f)",
+                  i, j, src_start, src_end, dst_start, dst_end);
+              if ((src_end <= dst_start) || (dst_end <= src_start)) {
+                after->bytes_amount[i*(src_nb+dst_nb)+src_nb+j]=0.0;
+              } else {
+                after->bytes_amount[i*(src_nb+dst_nb)+src_nb+j] =
+                   MIN(src_end, dst_end)- MAX(src_start, dst_start);
+              }
+              XBT_VERB("==> %.2f",
+                 after->bytes_amount[i*(src_nb+dst_nb)+src_nb+j]);
+            }
+          }
+
+          if (__SD_task_is_schedulable(after) ||
+              __SD_task_is_not_scheduled(after)) {
+            SD_task_do_schedule(after);
+            XBT_VERB
+            ("Auto-Schedule redistribution task %s. Send %.f bytes from %d hosts to %d hosts.",
+              SD_task_get_name(after),after->amount, src_nb, dst_nb);
+          }
+         }
+      }
+    }
+  }
 }
 
 /** @brief autoschedule a task on a list of workstations