X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/59ee07d949014eace7f574354a69fbba0fd2be4e..b1919c1826467eb2cfbc972842e0c39c5ab4d92c:/src/simdag/sd_task.c

diff --git a/src/simdag/sd_task.c b/src/simdag/sd_task.c
index f1d202feca..3673944cd3 100644
--- a/src/simdag/sd_task.c
+++ b/src/simdag/sd_task.c
@@ -16,39 +16,18 @@ XBT_LOG_NEW_DEFAULT_SUBCATEGORY(sd_task, sd,
 static void __SD_task_remove_dependencies(SD_task_t task);
 static void __SD_task_destroy_scheduling_data(SD_task_t task);
 
-void* SD_task_new_f(void) {
+void* SD_task_new_f(void)
+{
   SD_task_t task = xbt_new0(s_SD_task_t, 1);
   task->tasks_before = xbt_dynar_new(sizeof(SD_dependency_t), NULL);
   task->tasks_after = xbt_dynar_new(sizeof(SD_dependency_t), NULL);
 
   return task;
 }
-void SD_task_recycle_f(void *t) {
-  SD_task_t task = (SD_task_t)t;
-
-  __SD_task_remove_dependencies(task);
-  /* if the task was scheduled or runnable we have to free the scheduling parameters */
-  if (__SD_task_is_scheduled_or_runnable(task))
-    __SD_task_destroy_scheduling_data(task);
-  if (task->state_set != NULL) {/* would be null if just created */
-    xbt_swag_remove(task, task->state_set);
-  }
-  xbt_swag_remove(task, sd_global->return_set);
-
-  if (task->name != NULL)
-    xbt_free(task->name);
-
-  if (task->surf_action != NULL)
-    surf_workstation_model->action_unref(task->surf_action);
-
-  if (task->workstation_list != NULL)
-    xbt_free(task->workstation_list);
-
-  if (task->communication_amount)
-    xbt_free(task->communication_amount);
 
-  if (task->computation_amount)
-    xbt_free(task->computation_amount);
+void SD_task_recycle_f(void *t)
+{
+  SD_task_t task = (SD_task_t) t;
 
   /* Reset the content */
   task->kind = SD_TASK_NOT_TYPED;
@@ -68,8 +47,8 @@ void SD_task_recycle_f(void *t) {
   task->watch_points = 0;
 
   /* dependencies */
-  xbt_dynar_reset(task->tasks_before); // =  new(sizeof(SD_dependency_t), NULL);
-  xbt_dynar_reset(task->tasks_after);  // = xbt_dynar_new(sizeof(SD_dependency_t), NULL);
+  xbt_dynar_reset(task->tasks_before);
+  xbt_dynar_reset(task->tasks_after);
   task->unsatisfied_dependencies = 0;
   task->is_not_ready = 0;
 
@@ -79,47 +58,17 @@ void SD_task_recycle_f(void *t) {
   task->computation_amount = NULL;
   task->communication_amount = NULL;
   task->rate = -1;
-
-#ifdef HAVE_TRACING
-  TRACE_sd_task_create(task);
-#endif
 }
-void SD_task_free_f(void *t) {
-  SD_task_t task = (SD_task_t)t;
 
-  __SD_task_remove_dependencies(task);
-  /* if the task was scheduled or runnable we have to free the scheduling parameters */
-  if (__SD_task_is_scheduled_or_runnable(task))
-    __SD_task_destroy_scheduling_data(task);
-  if (task->state_set != NULL) /* would be null if just created */
-    xbt_swag_remove(task, task->state_set);
-
-  xbt_swag_remove(task, sd_global->return_set);
-
-  if (task->name != NULL)
-    xbt_free(task->name);
-
-  if (task->surf_action != NULL)
-    surf_workstation_model->action_unref(task->surf_action);
-
-  if (task->workstation_list != NULL)
-    xbt_free(task->workstation_list);
-
-  if (task->communication_amount)
-    xbt_free(task->communication_amount);
-
-  if (task->computation_amount)
-    xbt_free(task->computation_amount);
-#ifdef HAVE_TRACING
-  TRACE_sd_task_destroy(task);
-#endif
+void SD_task_free_f(void *t)
+{
+  SD_task_t task = (SD_task_t)t;
 
   xbt_dynar_free(&task->tasks_before);
   xbt_dynar_free(&task->tasks_after);
   xbt_free(task);
 }
 
-
 /**
  * \brief Creates a new task.
  *
@@ -141,8 +90,125 @@ SD_task_t SD_task_create(const char *name, void *data, double amount)
 
   sd_global->task_number++;
 
+#ifdef HAVE_TRACING
+  task->category = NULL;
+#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->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
+ *
+ * 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->communication_amount[2] = amount;
+  res->kind = SD_TASK_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 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 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 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_amdhal 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 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 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, amount);
+  res->alpha = alpha;
+  res->kind = SD_TASK_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;
+  return res;
+}
+
 /**
  * \brief Destroys a task.
  *
@@ -155,13 +221,34 @@ void SD_task_destroy(SD_task_t task)
 {
   XBT_DEBUG("Destroying task %s...", SD_task_get_name(task));
 
+  __SD_task_remove_dependencies(task);
+  /* if the task was scheduled or runnable we have to free the scheduling parameters */
+  if (__SD_task_is_scheduled_or_runnable(task))
+    __SD_task_destroy_scheduling_data(task);
+  if (task->state_set != NULL) /* would be null if just created */
+    xbt_swag_remove(task, task->state_set);
+
+  xbt_swag_remove(task, sd_global->return_set);
+
+  xbt_free(task->name);
+
+  if (task->surf_action != NULL)
+    surf_workstation_model->action_unref(task->surf_action);
+
+  xbt_free(task->workstation_list);
+  xbt_free(task->communication_amount);
+  xbt_free(task->computation_amount);
+
+#ifdef HAVE_TRACING
+  if (task->category) xbt_free(task->category);
+#endif
+
   xbt_mallocator_release(sd_global->task_mallocator,task);
   sd_global->task_number--;
 
   XBT_DEBUG("Task destroyed.");
 }
 
-
 /**
  * \brief Returns the user data of a task
  *
@@ -171,8 +258,6 @@ void SD_task_destroy(SD_task_t task)
  */
 void *SD_task_get_data(SD_task_t task)
 {
-  SD_CHECK_INIT_DONE();
-  xbt_assert(task != NULL, "Invalid parameter");
   return task->data;
 }
 
@@ -188,11 +273,31 @@ void *SD_task_get_data(SD_task_t task)
  */
 void SD_task_set_data(SD_task_t task, void *data)
 {
-  SD_CHECK_INIT_DONE();
-  xbt_assert(task != NULL, "Invalid parameter");
   task->data = data;
 }
 
+/**
+ * \brief Sets the rate of a task
+ *
+ * This will change the network bandwidth a task can use. 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.");
+
+  task->rate = rate;
+}
+
 /**
  * \brief Returns the state of a task
  *
@@ -203,8 +308,6 @@ void SD_task_set_data(SD_task_t task, void *data)
  */
 e_SD_task_state_t SD_task_get_state(SD_task_t task)
 {
-  SD_CHECK_INIT_DONE();
-  xbt_assert(task != NULL, "Invalid parameter");
   return task->state;
 }
 
@@ -267,8 +370,6 @@ void __SD_task_set_state(SD_task_t task, e_SD_task_state_t new_state)
  */
 const char *SD_task_get_name(SD_task_t task)
 {
-  SD_CHECK_INIT_DONE();
-  xbt_assert(task != NULL, "Invalid parameter");
   return task->name;
 }
 
@@ -290,8 +391,6 @@ xbt_dynar_t SD_task_get_parents(SD_task_t task)
   unsigned int i;
   xbt_dynar_t parents;
   SD_dependency_t dep;
-  SD_CHECK_INIT_DONE();
-  xbt_assert(task != NULL, "Invalid parameter");
 
   parents = xbt_dynar_new(sizeof(SD_task_t), NULL);
   xbt_dynar_foreach(task->tasks_before, i, dep) {
@@ -310,8 +409,6 @@ xbt_dynar_t SD_task_get_children(SD_task_t task)
   unsigned int i;
   xbt_dynar_t children;
   SD_dependency_t dep;
-  SD_CHECK_INIT_DONE();
-  xbt_assert(task != NULL, "Invalid parameter");
 
   children = xbt_dynar_new(sizeof(SD_task_t), NULL);
   xbt_dynar_foreach(task->tasks_after, i, dep) {
@@ -328,10 +425,6 @@ xbt_dynar_t SD_task_get_children(SD_task_t task)
  */
 int SD_task_get_workstation_count(SD_task_t task)
 {
-  SD_CHECK_INIT_DONE();
-  xbt_assert(task != NULL, "Invalid parameter");
-  //xbt_assert(task->state_set != sd_global->scheduled_task_set,
-  //           "Unscheduled task %s", task->name);
   return task->workstation_nb;
 }
 
@@ -343,10 +436,6 @@ int SD_task_get_workstation_count(SD_task_t task)
  */
 SD_workstation_t *SD_task_get_workstation_list(SD_task_t task)
 {
-  SD_CHECK_INIT_DONE();
-  xbt_assert(task != NULL, "Invalid parameter");
-  //xbt_assert(task->state_set != sd_global->scheduled_task_set,
-  //           "Unscheduled task %s", task->name);
   return task->workstation_list;
 }
 
@@ -359,8 +448,6 @@ SD_workstation_t *SD_task_get_workstation_list(SD_task_t task)
  */
 double SD_task_get_amount(SD_task_t task)
 {
-  SD_CHECK_INIT_DONE();
-  xbt_assert(task != NULL, "Invalid parameter");
   return task->amount;
 }
 
@@ -373,9 +460,6 @@ double SD_task_get_amount(SD_task_t task)
  */
 double SD_task_get_remaining_amount(SD_task_t task)
 {
-  SD_CHECK_INIT_DONE();
-  xbt_assert(task != NULL, "Invalid parameter");
-
   if (task->surf_action)
     return surf_workstation_model->get_remains(task->surf_action);
   else
@@ -417,19 +501,22 @@ 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;
     default:
       XBT_INFO("  - (unknown kind %d)", task->kind);
     }
   }
   XBT_INFO("  - amount: %.0f", SD_task_get_amount(task));
   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));
@@ -463,8 +550,7 @@ 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);
 }
 
@@ -489,9 +575,6 @@ void SD_task_dependency_add(const char *name, void *data, SD_task_t src,
   int i;
   SD_dependency_t dependency;
 
-  SD_CHECK_INIT_DONE();
-  xbt_assert(src != NULL && dst != NULL, "Invalid parameter");
-
   dynar = src->tasks_after;
   length = xbt_dynar_length(dynar);
 
@@ -501,9 +584,10 @@ 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)
@@ -548,13 +632,10 @@ 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);
   }
-
-  /*  __SD_print_dependencies(src);
-     __SD_print_dependencies(dst); */
 }
 
 /**
- * \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
@@ -567,7 +648,6 @@ int SD_task_dependency_exists(SD_task_t src, SD_task_t dst)
   unsigned int counter;
   SD_dependency_t dependency;
 
-  SD_CHECK_INIT_DONE();
   xbt_assert(src != NULL
               || dst != NULL,
               "Invalid parameter: both src and dst are NULL");
@@ -603,9 +683,6 @@ void SD_task_dependency_remove(SD_task_t src, SD_task_t dst)
   int i;
   SD_dependency_t dependency;
 
-  SD_CHECK_INIT_DONE();
-  xbt_assert(src != NULL && dst != NULL, "Invalid parameter");
-
   /* remove the dependency from src->tasks_after */
   dynar = src->tasks_after;
   length = xbt_dynar_length(dynar);
@@ -677,10 +754,6 @@ void *SD_task_dependency_get_data(SD_task_t src, SD_task_t dst)
   int i;
   SD_dependency_t dependency;
 
-
-  SD_CHECK_INIT_DONE();
-  xbt_assert(src != NULL && dst != NULL, "Invalid parameter");
-
   dynar = src->tasks_after;
   length = xbt_dynar_length(dynar);
 
@@ -731,9 +804,6 @@ static void __SD_print_watch_points(SD_task_t task)
  */
 void SD_task_watch(SD_task_t task, e_SD_task_state_t state)
 {
-  SD_CHECK_INIT_DONE();
-  xbt_assert(task != NULL, "Invalid parameter");
-
   if (state & SD_NOT_SCHEDULED)
     THROWF(arg_error, 0,
            "Cannot add a watch point for state SD_NOT_SCHEDULED");
@@ -751,8 +821,6 @@ void SD_task_watch(SD_task_t task, e_SD_task_state_t state)
  */
 void SD_task_unwatch(SD_task_t task, e_SD_task_state_t state)
 {
-  SD_CHECK_INIT_DONE();
-  xbt_assert(task != NULL, "Invalid parameter");
   xbt_assert(state != SD_NOT_SCHEDULED,
               "SimDag error: Cannot have a watch point for state SD_NOT_SCHEDULED");
 
@@ -782,9 +850,7 @@ double SD_task_get_execution_time(SD_task_t task,
 {
   double time, max_time = 0.0;
   int i, j;
-  SD_CHECK_INIT_DONE();
-  xbt_assert(task != NULL && workstation_nb > 0
-              && workstation_list != NULL, "Invalid parameter");
+  xbt_assert(workstation_nb > 0, "Invalid parameter");
 
   /* the task execution time is the maximum execution time of the parallel tasks */
 
@@ -814,8 +880,6 @@ double SD_task_get_execution_time(SD_task_t task,
 
 static XBT_INLINE void SD_task_do_schedule(SD_task_t task)
 {
-  SD_CHECK_INIT_DONE();
-
   if (!__SD_task_is_not_scheduled(task) && !__SD_task_is_schedulable(task))
     THROWF(arg_error, 0, "Task '%s' has already been scheduled",
            SD_task_get_name(task));
@@ -897,9 +961,6 @@ void SD_task_schedule(SD_task_t task, int workstation_count,
  */
 void SD_task_unschedule(SD_task_t task)
 {
-  SD_CHECK_INIT_DONE();
-  xbt_assert(task != NULL, "Invalid parameter");
-
   if (task->state_set != sd_global->scheduled_task_set &&
       task->state_set != sd_global->runnable_task_set &&
       task->state_set != sd_global->running_task_set &&
@@ -909,8 +970,12 @@ 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);
+    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);
@@ -924,11 +989,11 @@ 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)
 {
-  SD_CHECK_INIT_DONE();
   if (!__SD_task_is_scheduled_or_runnable(task)
       && !__SD_task_is_in_fifo(task))
     THROWF(arg_error, 0,
@@ -940,9 +1005,9 @@ static void __SD_task_destroy_scheduling_data(SD_task_t task)
   task->computation_amount = task->communication_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)
 {
@@ -950,21 +1015,18 @@ void __SD_task_really_run(SD_task_t task)
   int i;
   void **surf_workstations;
 
-  SD_CHECK_INIT_DONE();
-  xbt_assert(task != NULL, "Invalid parameter");
   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 workstation_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 < workstation_nb; i++) {
     if (SD_workstation_get_access_mode(task->workstation_list[i]) ==
         SD_WORKSTATION_SEQUENTIAL_ACCESS) {
       task->workstation_list[i]->current_task = task;
@@ -978,71 +1040,31 @@ 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);
+  /* we have to create a Surf workstation array instead of the SimDag
+   * workstation array */
+  surf_workstations = xbt_new(void *, workstation_nb);
 
-  for (i = 0; i < task->workstation_nb; i++)
+  for (i = 0; i < workstation_nb; i++)
     surf_workstations[i] = task->workstation_list[i]->surf_workstation;
 
-  /* 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 *computation_amount = xbt_new0(double, workstation_nb);
+  double *communication_amount = xbt_new0(double, workstation_nb * workstation_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);
 
+  if(task->computation_amount)
     memcpy(computation_amount, task->computation_amount, sizeof(double) *
-           task->workstation_nb);
+           workstation_nb);
+  if(task->communication_amount)
     memcpy(communication_amount, task->communication_amount,
-           sizeof(double) * task->workstation_nb * task->workstation_nb);
+           sizeof(double) * workstation_nb * workstation_nb);
 
-    task->surf_action =
+  task->surf_action =
         surf_workstation_model->extension.
-        workstation.execute_parallel_task(task->workstation_nb,
+        workstation.execute_parallel_task(workstation_nb,
                                           surf_workstations,
                                           computation_amount,
                                           communication_amount,
-                                          task->amount, task->rate);
-  } else {
-    xbt_free(surf_workstations);
-  }
+                                          task->rate);
 
   surf_workstation_model->action_data_set(task->surf_action, task);
 
@@ -1056,14 +1078,15 @@ void __SD_task_really_run(SD_task_t task)
   __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)
@@ -1073,11 +1096,9 @@ int __SD_task_try_to_run(SD_task_t task)
   int i;
   SD_workstation_t workstation;
 
-  SD_CHECK_INIT_DONE();
-  xbt_assert(task != NULL, "Invalid parameter");
   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++) {
@@ -1087,11 +1108,11 @@ 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'",
+        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);
@@ -1099,7 +1120,7 @@ int __SD_task_try_to_run(SD_task_t 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);
@@ -1110,7 +1131,7 @@ 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)
 {
@@ -1123,11 +1144,9 @@ void __SD_task_just_done(SD_task_t task)
   SD_task_t *candidates;
   int can_start = 1;
 
-  SD_CHECK_INIT_DONE();
-  xbt_assert(task != NULL, "Invalid parameter");
   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));
@@ -1142,14 +1161,14 @@ void __SD_task_just_done(SD_task_t task)
   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);
+              SD_workstation_get_name(workstation), (int)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!",
+                  "Workstation '%s' has sequential access but no FIFO!",
                   SD_workstation_get_name(workstation));
       xbt_assert(workstation->current_task =
                   task, "Workstation '%s': current task should be '%s'",
@@ -1159,7 +1178,7 @@ void __SD_task_just_done(SD_task_t task)
       /* the task is over so we can release the workstation */
       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));
@@ -1169,7 +1188,7 @@ 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));
+                    (int)SD_task_get_state(candidate));
       }
 
       XBT_DEBUG("Candidate in fifo: %p", candidate);
@@ -1177,9 +1196,10 @@ 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) {
@@ -1208,13 +1228,13 @@ 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 */
+         or if I am the first task in the FIFO */
       can_start = workstation->access_mode == SD_WORKSTATION_SHARED_ACCESS
           || candidate ==
           xbt_fifo_get_item_content(xbt_fifo_get_first_item
@@ -1229,20 +1249,20 @@ 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 */
+        /* 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'",
+          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
@@ -1252,7 +1272,7 @@ 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 */
@@ -1262,19 +1282,21 @@ 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);
   }
@@ -1290,8 +1312,6 @@ static void __SD_task_remove_dependencies(SD_task_t task)
  */
 double SD_task_get_start_time(SD_task_t task)
 {
-  SD_CHECK_INIT_DONE();
-  xbt_assert(task != NULL, "Invalid parameter");
   if (task->surf_action)
     return surf_workstation_model->
         action_get_start_time(task->surf_action);
@@ -1312,100 +1332,80 @@ double SD_task_get_start_time(SD_task_t task)
  */
 double SD_task_get_finish_time(SD_task_t task)
 {
-  SD_CHECK_INIT_DONE();
-  xbt_assert(task != NULL, "Invalid parameter");
-
   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);
   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)
+/** @brief Blah
+ *
+ */
+void SD_task_distribute_comp_amdhal(SD_task_t task, int ws_count)
 {
-  SD_task_t task = SD_task_create(name, data, amount);
-  task->communication_amount = xbt_new0(double, ws_count * ws_count);
+  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->computation_amount = xbt_new0(double, ws_count);
+  task->communication_amount = xbt_new0(double, ws_count * 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 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)
-{
-  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;
-}
+  
+  for(i=0;i<ws_count;i++){
+    task->computation_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_amdhal(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->computation_amount){
+      /*This task has failed and is rescheduled. Reset the computation amount*/
+      task->computation_amount = xbt_new0(double, 1);
+      task->computation_amount[0] = task->remains;
+    }
     SD_task_do_schedule(task);
     break;
   default:
@@ -1420,7 +1420,9 @@ void SD_task_schedulev(SD_task_t task, int count,
           task->communication_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),
@@ -1449,7 +1451,6 @@ 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))) {
@@ -1465,6 +1466,134 @@ void SD_task_schedulev(SD_task_t task, int count,
       }
     }
   }
+  /* 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'Law",
+          SD_task_get_name(task), task->workstation_nb,
+          task->computation_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. Fill the workstation list with receiver side",
+             SD_task_get_name(before));
+          before->workstation_list = xbt_new0(SD_workstation_t, count);
+          before->workstation_nb = count;
+          for (i=0;i<count;i++)
+            before->workstation_list[i] = task->workstation_list[i];
+        } else {
+          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;
+
+          before->computation_amount = xbt_new0(double,
+                                                before->workstation_nb);
+          before->communication_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->communication_amount[i*(src_nb+dst_nb)+src_nb+j]=0.0;
+              } else {
+                before->communication_amount[i*(src_nb+dst_nb)+src_nb+j] =
+                  MIN(src_end, dst_end) - MAX(src_start, dst_start);
+              }
+              XBT_VERB("==> %.2f",
+                 before->communication_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. Fill the workstation list with sender side",
+              SD_task_get_name(after));
+          after->workstation_list = xbt_new0(SD_workstation_t, count);
+          after->workstation_nb = count;
+          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;
+
+          after->computation_amount = xbt_new0(double, after->workstation_nb);
+          after->communication_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->communication_amount[i*(src_nb+dst_nb)+src_nb+j]=0.0;
+              } else {
+                after->communication_amount[i*(src_nb+dst_nb)+src_nb+j] =
+                   MIN(src_end, dst_end)- MAX(src_start, dst_start);
+              }
+              XBT_VERB("==> %.2f",
+                 after->communication_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
@@ -1486,3 +1615,50 @@ void SD_task_schedulel(SD_task_t task, int count, ...)
   SD_task_schedulev(task, count, list);
   free(list);
 }
+
+/**
+ * \brief Sets the tracing category of a task.
+ *
+ * This function should be called after the creation of a
+ * SimDAG task, to define the category of that task. The first
+ * parameter must contain a task that was created with the
+ * function #SD_task_create. The second parameter must contain
+ * a category that was previously declared with the function
+ * #TRACE_category.
+ *
+ * \param task The task to be considered
+ * \param category the name of the category to be associated to the task
+ *
+ * \see SD_task_get_category, TRACE_category, TRACE_category_with_color
+ */
+void SD_task_set_category (SD_task_t task, const char *category)
+{
+#ifdef HAVE_TRACING
+  if (!TRACE_is_enabled()) return;
+  if (task == NULL) return;
+  if (category == NULL){
+    if (task->category) xbt_free (task->category);
+    task->category = NULL;
+  }else{
+    task->category = xbt_strdup (category);
+  }
+#endif
+}
+
+/**
+ * \brief Gets the current tracing category of a task.
+ *
+ * \param task The task to be considered
+ *
+ * \see SD_task_set_category
+ *
+ * \return Returns the name of the tracing category of the given task, NULL otherwise
+ */
+const char *SD_task_get_category (SD_task_t task)
+{
+#ifdef HAVE_TRACING
+  return task->category;
+#else
+  return NULL;
+#endif
+}