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Parmap: protect against wraparound for round.
[simgrid.git] / src / xbt / parmap.c
index c88a26b..8219493 100644 (file)
@@ -5,27 +5,88 @@
  * under the terms of the license (GNU LGPL) which comes with this package. */
 #include "gras_config.h"
 #include <unistd.h>
+
 #ifndef _XBT_WIN32
 #include <sys/syscall.h>
 #endif
 
 #ifdef HAVE_FUTEX_H
-       #include <linux/futex.h>
-#else
-       #include "xbt/xbt_os_thread.h"
+#include <linux/futex.h>
+#include <limits.h>
 #endif
-#include <errno.h>
-#include "parmap_private.h"
+
+#include "xbt/parmap.h"
+#include "xbt/log.h"
+#include "xbt/function_types.h"
+#include "xbt/dynar.h"
+#include "xbt/xbt_os_thread.h"
+#include "xbt/sysdep.h"
 
 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(xbt_parmap, xbt, "parmap: parallel map");
 XBT_LOG_NEW_SUBCATEGORY(xbt_parmap_unit, xbt_parmap, "parmap unit testing");
 
-static void *_xbt_parmap_worker_main(void *parmap);
+typedef enum {
+  XBT_PARMAP_WORK,
+  XBT_PARMAP_DESTROY
+} e_xbt_parmap_flag_t;
+
+static void xbt_parmap_set_mode(xbt_parmap_t parmap, e_xbt_parmap_mode_t mode);
+static void *xbt_parmap_worker_main(void *parmap);
+static void xbt_parmap_work(xbt_parmap_t parmap);
+
+static void xbt_parmap_posix_master_wait(xbt_parmap_t parmap);
+static void xbt_parmap_posix_worker_signal(xbt_parmap_t parmap);
+static void xbt_parmap_posix_master_signal(xbt_parmap_t parmap);
+static void xbt_parmap_posix_worker_wait(xbt_parmap_t parmap, unsigned round);
+
 #ifdef HAVE_FUTEX_H
-       static void futex_wait(int *uaddr, int val);
-       static void futex_wake(int *uaddr, int val);
+static void xbt_parmap_futex_master_wait(xbt_parmap_t parmap);
+static void xbt_parmap_futex_worker_signal(xbt_parmap_t parmap);
+static void xbt_parmap_futex_master_signal(xbt_parmap_t parmap);
+static void xbt_parmap_futex_worker_wait(xbt_parmap_t parmap, unsigned round);
+static void futex_wait(unsigned *uaddr, unsigned val);
+static void futex_wake(unsigned *uaddr, unsigned val);
 #endif
-xbt_parmap_t xbt_parmap_new(unsigned int num_workers)
+
+static void xbt_parmap_busy_master_wait(xbt_parmap_t parmap);
+static void xbt_parmap_busy_worker_signal(xbt_parmap_t parmap);
+static void xbt_parmap_busy_master_signal(xbt_parmap_t parmap);
+static void xbt_parmap_busy_worker_wait(xbt_parmap_t parmap, unsigned round);
+
+/**
+ * \brief Parallel map structure
+ */
+typedef struct s_xbt_parmap {
+  e_xbt_parmap_flag_t status;      /**< is the parmap active or being destroyed? */
+  unsigned work;                   /**< index of the current round */
+  unsigned thread_counter;         /**< number of workers that have done the work */
+
+  unsigned int num_workers;        /**< total number of worker threads including the controller */
+  void_f_pvoid_t fun;              /**< function to run in parallel on each element of data */
+  xbt_dynar_t data;                /**< parameters to pass to fun in parallel */
+  unsigned int index;              /**< index of the next element of data to pick */
+
+  /* posix only */
+  xbt_os_cond_t ready_cond;
+  xbt_os_mutex_t ready_mutex;
+  xbt_os_cond_t done_cond;
+  xbt_os_mutex_t done_mutex;
+
+  /* fields that depend on the synchronization mode */
+  e_xbt_parmap_mode_t mode;        /**< synchronization mode */
+  void (*master_wait_f)(xbt_parmap_t);    /**< wait for the workers to have done the work */
+  void (*worker_signal_f)(xbt_parmap_t);  /**< signal the master that a worker has done the work */
+  void (*master_signal_f)(xbt_parmap_t);  /**< wakes the workers threads to process tasks */
+  void (*worker_wait_f)(xbt_parmap_t, unsigned); /**< waits for more work */
+} s_xbt_parmap_t;
+
+/**
+ * \brief Creates a parallel map object
+ * \param num_workers number of worker threads to create
+ * \param mode how to synchronize the worker threads
+ * \return the parmap created
+ */
+xbt_parmap_t xbt_parmap_new(unsigned int num_workers, e_xbt_parmap_mode_t mode)
 {
   unsigned int i;
   xbt_os_thread_t worker = NULL;
@@ -34,183 +95,533 @@ xbt_parmap_t xbt_parmap_new(unsigned int num_workers)
 
   /* Initialize the thread pool data structure */
   xbt_parmap_t parmap = xbt_new0(s_xbt_parmap_t, 1);
-#ifdef HAVE_FUTEX_H
-  parmap->sync_event = xbt_new0(s_xbt_event_t, 1);
-#endif
+
   parmap->num_workers = num_workers;
-  parmap->status = PARMAP_WORK;
-#ifdef HAVE_FUTEX_H
-  parmap->sync_event->threads_to_wait = num_workers;
-#endif
+  parmap->status = XBT_PARMAP_WORK;
+  xbt_parmap_set_mode(parmap, mode);
+
   /* Create the pool of worker threads */
-  for(i=0; i < num_workers; i++){
-    worker = xbt_os_thread_create(NULL, _xbt_parmap_worker_main, parmap, NULL);
+  for (i = 1; i < num_workers; i++) {
+    worker = xbt_os_thread_create(NULL, xbt_parmap_worker_main, parmap, NULL);
     xbt_os_thread_detach(worker);
   }
-#ifdef HAVE_FUTEX_H
-  xbt_event_init(parmap->sync_event);
-#endif
   return parmap;
 }
 
+/**
+ * \brief Destroys a parmap
+ * \param parmap the parmap to destroy
+ */
 void xbt_parmap_destroy(xbt_parmap_t parmap)
-{ 
-  XBT_DEBUG("Destroy parmap %p", parmap);
-  parmap->status = PARMAP_DESTROY;
+{
+  if (!parmap) {
+    return;
+  }
+
+  parmap->status = XBT_PARMAP_DESTROY;
+  parmap->master_signal_f(parmap);
+  parmap->master_wait_f(parmap);
+
+  xbt_os_cond_destroy(parmap->ready_cond);
+  xbt_os_mutex_destroy(parmap->ready_mutex);
+  xbt_os_cond_destroy(parmap->done_cond);
+  xbt_os_mutex_destroy(parmap->done_mutex);
+
+  xbt_free(parmap);
+}
+
+/**
+ * \brief Sets the synchronization mode of a parmap.
+ * \param parmap a parallel map object
+ * \param mode the synchronization mode
+ */
+static void xbt_parmap_set_mode(xbt_parmap_t parmap, e_xbt_parmap_mode_t mode)
+{
+  if (mode == XBT_PARMAP_DEFAULT) {
 #ifdef HAVE_FUTEX_H
-  xbt_event_signal(parmap->sync_event);
-  xbt_free(parmap->sync_event);
+    mode = XBT_PARMAP_FUTEX;
+#else
+    mode = XBT_PARMAP_POSIX;
 #endif
-  xbt_free(parmap);
+  }
+  parmap->mode = mode;
+
+  switch (mode) {
+
+    case XBT_PARMAP_POSIX:
+      parmap->master_wait_f = xbt_parmap_posix_master_wait;
+      parmap->worker_signal_f = xbt_parmap_posix_worker_signal;
+      parmap->master_signal_f = xbt_parmap_posix_master_signal;
+      parmap->worker_wait_f = xbt_parmap_posix_worker_wait;
+
+      parmap->ready_cond = xbt_os_cond_init();
+      parmap->ready_mutex = xbt_os_mutex_init();
+      parmap->done_cond = xbt_os_cond_init();
+      parmap->done_mutex = xbt_os_mutex_init();
+      break;
+
+
+    case XBT_PARMAP_FUTEX:
+#ifdef HAVE_FUTEX_H
+      parmap->master_wait_f = xbt_parmap_futex_master_wait;
+      parmap->worker_signal_f = xbt_parmap_futex_worker_signal;
+      parmap->master_signal_f = xbt_parmap_futex_master_signal;
+      parmap->worker_wait_f = xbt_parmap_futex_worker_wait;
+
+      xbt_os_cond_destroy(parmap->ready_cond);
+      xbt_os_mutex_destroy(parmap->ready_mutex);
+      xbt_os_cond_destroy(parmap->done_cond);
+      xbt_os_mutex_destroy(parmap->done_mutex);
+      break;
+#else
+      xbt_die("Futex is not available on this OS.");
+#endif
+
+    case XBT_PARMAP_BUSY_WAIT:
+      parmap->master_wait_f = xbt_parmap_busy_master_wait;
+      parmap->worker_signal_f = xbt_parmap_busy_worker_signal;
+      parmap->master_signal_f = xbt_parmap_busy_master_signal;
+      parmap->worker_wait_f = xbt_parmap_busy_worker_wait;
+
+      xbt_os_cond_destroy(parmap->ready_cond);
+      xbt_os_mutex_destroy(parmap->ready_mutex);
+      xbt_os_cond_destroy(parmap->done_cond);
+      xbt_os_mutex_destroy(parmap->done_mutex);
+      break;
+
+    case XBT_PARMAP_DEFAULT:
+      THROW_IMPOSSIBLE;
+      break;
+  }
 }
 
- void xbt_parmap_apply(xbt_parmap_t parmap, void_f_pvoid_t fun, xbt_dynar_t data)
+/**
+ * \brief Applies a list of tasks in parallel.
+ * \param parmap a parallel map object
+ * \param fun the function to call in parallel
+ * \param data each element of this dynar will be passed as an argument to fun
+ */
+void xbt_parmap_apply(xbt_parmap_t parmap, void_f_pvoid_t fun, xbt_dynar_t data)
 {
-  /* Assign resources to worker threads*/
+  /* Assign resources to worker threads */
   parmap->fun = fun;
   parmap->data = data;
   parmap->index = 0;
-#ifdef HAVE_FUTEX_H
-  xbt_event_signal(parmap->sync_event);
-#endif
+  parmap->master_signal_f(parmap);
+  xbt_parmap_work(parmap);
+  parmap->master_wait_f(parmap);
   XBT_DEBUG("Job done");
 }
 
-static void *_xbt_parmap_worker_main(void *arg)
+/**
+ * \brief Returns a next task to process.
+ *
+ * Worker threads call this function to get more work.
+ *
+ * \return the next task to process, or NULL if there is no more work
+ */
+void* xbt_parmap_next(xbt_parmap_t parmap)
 {
-  unsigned int worker_id;
-  xbt_parmap_t parmap = (xbt_parmap_t)arg;
+  unsigned int index = __sync_fetch_and_add(&parmap->index, 1);
+  if (index < xbt_dynar_length(parmap->data)) {
+    return xbt_dynar_get_as(parmap->data, index, void*);
+  }
+  return NULL;
+}
 
-  /* Fetch a worker id */
-  worker_id = __sync_fetch_and_add(&parmap->workers_max_id, 1);
-  xbt_os_thread_set_extra_data((void *)(unsigned long)worker_id);
+static void xbt_parmap_work(xbt_parmap_t parmap)
+{
+  unsigned index;
+  while ((index = __sync_fetch_and_add(&parmap->index, 1))
+         < xbt_dynar_length(parmap->data))
+    parmap->fun(xbt_dynar_get_as(parmap->data, index, void*));
+}
+
+/**
+ * \brief Main function of a worker thread.
+ * \param arg the parmap
+ */
+static void *xbt_parmap_worker_main(void *arg)
+{
+  xbt_parmap_t parmap = (xbt_parmap_t) arg;
+  unsigned round = 0;
+
+  XBT_DEBUG("New worker thread created");
 
-  XBT_DEBUG("New worker thread created (%u)", worker_id);
-  
   /* Worker's main loop */
-  while(1){
-#ifdef HAVE_FUTEX_H
-    xbt_event_wait(parmap->sync_event);
-#endif
-    if(parmap->status == PARMAP_WORK){
-      unsigned int i;
-      unsigned int n = 0;
+  while (1) {
+    parmap->worker_wait_f(parmap, ++round);
+    if (parmap->status == XBT_PARMAP_WORK) {
 
-      XBT_DEBUG("Worker %u got a job", worker_id);
+      XBT_DEBUG("Worker got a job");
 
-      while ((i = __sync_fetch_and_add(&parmap->index, 1))
-             < xbt_dynar_length(parmap->data)) {
-        parmap->fun(xbt_dynar_get_as(parmap->data, i, void*));
-        n++;
-      }
+      xbt_parmap_work(parmap);
+      parmap->worker_signal_f(parmap);
 
-      XBT_DEBUG("Worker %u processed %u tasks", worker_id, n);
+      XBT_DEBUG("Worker has finished");
 
     /* We are destroying the parmap */
-    }else{
-#ifdef HAVE_FUTEX_H
-      xbt_event_end(parmap->sync_event);
-#endif
-      XBT_DEBUG("Shutting down worker %u", worker_id);
+    } else {
+      parmap->worker_signal_f(parmap);
       return NULL;
     }
   }
 }
 
 #ifdef HAVE_FUTEX_H
-static void futex_wait(int *uaddr, int val)
+static void futex_wait(unsigned *uaddr, unsigned val)
 {
   XBT_VERB("Waiting on futex %p", uaddr);
   syscall(SYS_futex, uaddr, FUTEX_WAIT_PRIVATE, val, NULL, NULL, 0);
 }
 
-static void futex_wake(int *uaddr, int val)
+static void futex_wake(unsigned *uaddr, unsigned val)
 {
   XBT_VERB("Waking futex %p", uaddr);
   syscall(SYS_futex, uaddr, FUTEX_WAKE_PRIVATE, val, NULL, NULL, 0);
 }
+#endif
 
-void xbt_event_init(xbt_event_t event)
+/**
+ * \brief Starts the parmap: waits for all workers to be ready and returns.
+ *
+ * This function is called by the controller thread.
+ *
+ * \param parmap a parmap
+ */
+static void xbt_parmap_posix_master_wait(xbt_parmap_t parmap)
 {
-  int myflag = event->done;
-  if(event->thread_counter < event->threads_to_wait)
-    futex_wait(&event->done, myflag);
+  xbt_os_mutex_acquire(parmap->done_mutex);
+  if (parmap->thread_counter < parmap->num_workers) {
+    /* wait for all workers to be ready */
+    xbt_os_cond_wait(parmap->done_cond, parmap->done_mutex);
+  }
+  xbt_os_mutex_release(parmap->done_mutex);
 }
 
-void xbt_event_signal(xbt_event_t event)
+/**
+ * \brief Ends the parmap: wakes the controller thread when all workers terminate.
+ *
+ * This function is called by all worker threads when they end (not including
+ * the controller).
+ *
+ * \param parmap a parmap
+ */
+static void xbt_parmap_posix_worker_signal(xbt_parmap_t parmap)
 {
-  int myflag = event->done;
-  event->thread_counter = 0;
-  event->work++;
-  futex_wake(&event->work, event->threads_to_wait);
-  futex_wait(&event->done, myflag);
+  xbt_os_mutex_acquire(parmap->done_mutex);
+  if (++parmap->thread_counter == parmap->num_workers) {
+    /* all workers have finished, wake the controller */
+    xbt_os_cond_signal(parmap->done_cond);
+  }
+  xbt_os_mutex_release(parmap->done_mutex);
 }
 
-void xbt_event_wait(xbt_event_t event)
+/**
+ * \brief Wakes all workers and waits for them to finish the tasks.
+ *
+ * This function is called by the controller thread.
+ *
+ * \param parmap a parmap
+ */
+static void xbt_parmap_posix_master_signal(xbt_parmap_t parmap)
 {
-  int myflag;
-  unsigned int mycount;
+  xbt_os_mutex_acquire(parmap->ready_mutex);
+  parmap->thread_counter = 1;
+  parmap->work++;
+  /* wake all workers */
+  xbt_os_cond_broadcast(parmap->ready_cond);
+  xbt_os_mutex_release(parmap->ready_mutex);
+}
 
-  myflag = event->work;
-  mycount = __sync_add_and_fetch(&event->thread_counter, 1);
-  if(mycount == event->threads_to_wait){
-    event->done++;
-    futex_wake(&event->done, 1);
+/**
+ * \brief Waits for some work to process.
+ *
+ * This function is called by each worker thread (not including the controller)
+ * when it has no more work to do.
+ *
+ * \param parmap a parmap
+ * \param round  the expected round number
+ */
+static void xbt_parmap_posix_worker_wait(xbt_parmap_t parmap, unsigned round)
+{
+  xbt_os_mutex_acquire(parmap->ready_mutex);
+  /* wait for more work */
+  if (parmap->work != round) {
+    xbt_os_cond_wait(parmap->ready_cond, parmap->ready_mutex);
   }
-
-  futex_wait(&event->work, myflag);
+  xbt_os_mutex_release(parmap->ready_mutex);
 }
 
-void xbt_event_end(xbt_event_t event)
+#ifdef HAVE_FUTEX_H
+/**
+ * \brief Starts the parmap: waits for all workers to be ready and returns.
+ *
+ * This function is called by the controller thread.
+ *
+ * \param parmap a parmap
+ */
+static void xbt_parmap_futex_master_wait(xbt_parmap_t parmap)
 {
-  unsigned int mycount;
+  unsigned count = parmap->thread_counter;
+  while (count < parmap->num_workers) {
+    /* wait for all workers to be ready */
+    futex_wait(&parmap->thread_counter, count);
+    count = parmap->thread_counter;
+  }
+}
 
-  mycount = __sync_add_and_fetch(&event->thread_counter, 1);
-  if(mycount == event->threads_to_wait){
-    event->done++;
-    futex_wake(&event->done, 1);
+/**
+ * \brief Ends the parmap: wakes the controller thread when all workers terminate.
+ *
+ * This function is called by all worker threads when they end (not including
+ * the controller).
+ *
+ * \param parmap a parmap
+ */
+static void xbt_parmap_futex_worker_signal(xbt_parmap_t parmap)
+{
+  unsigned count = __sync_add_and_fetch(&parmap->thread_counter, 1);
+  if (count == parmap->num_workers) {
+    /* all workers have finished, wake the controller */
+    futex_wake(&parmap->thread_counter, INT_MAX);
   }
 }
+
+/**
+ * \brief Wakes all workers and waits for them to finish the tasks.
+ *
+ * This function is called by the controller thread.
+ *
+ * \param parmap a parmap
+ */
+static void xbt_parmap_futex_master_signal(xbt_parmap_t parmap)
+{
+  parmap->thread_counter = 1;
+  __sync_add_and_fetch(&parmap->work, 1);
+  /* wake all workers */
+  futex_wake(&parmap->work, INT_MAX);
+}
+
+/**
+ * \brief Waits for some work to process.
+ *
+ * This function is called by each worker thread (not including the controller)
+ * when it has no more work to do.
+ *
+ * \param parmap a parmap
+ * \param round  the expected round number
+ */
+static void xbt_parmap_futex_worker_wait(xbt_parmap_t parmap, unsigned round)
+{
+  unsigned work = parmap->work;
+  /* wait for more work */
+  if (work != round)
+    futex_wait(&parmap->work, work);
+}
 #endif
 
+/**
+ * \brief Starts the parmap: waits for all workers to be ready and returns.
+ *
+ * This function is called by the controller thread.
+ *
+ * \param parmap a parmap
+ */
+static void xbt_parmap_busy_master_wait(xbt_parmap_t parmap)
+{
+  while (parmap->thread_counter < parmap->num_workers) {
+    xbt_os_thread_yield();
+  }
+}
+
+/**
+ * \brief Ends the parmap: wakes the controller thread when all workers terminate.
+ *
+ * This function is called by all worker threads when they end.
+ *
+ * \param parmap a parmap
+ */
+static void xbt_parmap_busy_worker_signal(xbt_parmap_t parmap)
+{
+  __sync_add_and_fetch(&parmap->thread_counter, 1);
+}
+
+/**
+ * \brief Wakes all workers and waits for them to finish the tasks.
+ *
+ * This function is called by the controller thread.
+ *
+ * \param parmap a parmap
+ */
+static void xbt_parmap_busy_master_signal(xbt_parmap_t parmap)
+{
+  parmap->thread_counter = 1;
+  __sync_add_and_fetch(&parmap->work, 1);
+}
+
+/**
+ * \brief Waits for some work to process.
+ *
+ * This function is called by each worker thread (not including the controller)
+ * when it has no more work to do.
+ *
+ * \param parmap a parmap
+ * \param round  the expected round number
+ */
+static void xbt_parmap_busy_worker_wait(xbt_parmap_t parmap, unsigned round)
+{
+  /* wait for more work */
+  while (parmap->work != round) {
+    xbt_os_thread_yield();
+  }
+}
+
 #ifdef SIMGRID_TEST
 #include "xbt.h"
 #include "xbt/ex.h"
+#include "xbt/xbt_os_thread.h"
+#include "xbt/xbt_os_time.h"
+#include "gras_config.h"        /* HAVE_FUTEX_H */
 
 XBT_TEST_SUITE("parmap", "Parallel Map");
 XBT_LOG_EXTERNAL_DEFAULT_CATEGORY(xbt_parmap_unit);
 
+#ifdef HAVE_FUTEX_H
+#define TEST_PARMAP_SKIP_TEST(mode) 0
+#else
+#define TEST_PARMAP_SKIP_TEST(mode) ((mode) == XBT_PARMAP_FUTEX)
+#endif
+
+#define TEST_PARMAP_VALIDATE_MODE(mode) \
+  if (TEST_PARMAP_SKIP_TEST(mode)) { xbt_test_skip(); return; } else ((void)0)
+
+static void fun_double(void *arg)
+{
+  unsigned *u = arg;
+  *u = 2 * *u + 1;
+}
+
+/* Check that the computations are correctly done. */
+static void test_parmap_basic(e_xbt_parmap_mode_t mode)
+{
+  unsigned num_workers;
+
+  for (num_workers = 1 ; num_workers <= 16 ; num_workers *= 2) {
+    const unsigned len = 1033;
+    const unsigned num = 5;
+    unsigned *a;
+    xbt_dynar_t data;
+    xbt_parmap_t parmap;
+    unsigned i;
+
+    xbt_test_add("Basic parmap usage (%u workers)", num_workers);
+
+    TEST_PARMAP_VALIDATE_MODE(mode);
+    parmap = xbt_parmap_new(num_workers, mode);
+
+    a = xbt_malloc(len * sizeof *a);
+    data = xbt_dynar_new(sizeof a, NULL);
+    for (i = 0; i < len; i++) {
+      a[i] = i;
+      xbt_dynar_push_as(data, void *, &a[i]);
+    }
 
+    for (i = 0; i < num; i++)
+      xbt_parmap_apply(parmap, fun_double, data);
 
-xbt_parmap_t parmap;
+    for (i = 0; i < len; i++) {
+      unsigned expected = (1U << num) * (i + 1) - 1;
+      xbt_test_assert(a[i] == expected,
+                      "a[%u]: expected %u, got %u", i, expected, a[i]);
+    }
 
-void fun(void *arg);
+    xbt_dynar_free(&data);
+    xbt_free(a);
+    xbt_parmap_destroy(parmap);
+  }
+}
 
-void fun(void *arg)
+XBT_TEST_UNIT("basic_posix", test_parmap_basic_posix, "Basic usage: posix")
 {
-  //XBT_INFO("I'm job %lu", (unsigned long)arg);
+  test_parmap_basic(XBT_PARMAP_POSIX);
 }
 
-XBT_TEST_UNIT("basic", test_parmap_basic, "Basic usage")
+XBT_TEST_UNIT("basic_futex", test_parmap_basic_futex, "Basic usage: futex")
 {
-  xbt_test_add("Create the parmap");
+  test_parmap_basic(XBT_PARMAP_FUTEX);
+}
 
-  unsigned long i,j;
-  xbt_dynar_t data = xbt_dynar_new(sizeof(void *), NULL);
+XBT_TEST_UNIT("basic_busy_wait", test_parmap_basic_busy_wait, "Basic usage: busy_wait")
+{
+  test_parmap_basic(XBT_PARMAP_BUSY_WAIT);
+}
 
-  /* Create the parallel map */
-  parmap = xbt_parmap_new(10);
+static void fun_get_id(void *arg)
+{
+  *(uintptr_t *)arg = (uintptr_t)xbt_os_thread_self();
+  xbt_os_sleep(0.5);
+}
 
-  for(j=0; j < 100; j++){
-    xbt_dynar_push_as(data, void *, (void *)j);
+static int fun_compare(const void *pa, const void *pb)
+{
+  uintptr_t a = *(uintptr_t *)pa;
+  uintptr_t b = *(uintptr_t *)pb;
+  return a < b ? -1 : a > b ? 1 : 0;
+}
+
+/* Check that all threads are working. */
+static void test_parmap_extended(e_xbt_parmap_mode_t mode)
+{
+  unsigned num_workers;
+
+  for (num_workers = 1 ; num_workers <= 16 ; num_workers *= 2) {
+    const unsigned len = 2 * num_workers;
+    uintptr_t *a;
+    xbt_parmap_t parmap;
+    xbt_dynar_t data;
+    unsigned i;
+    unsigned count;
+
+    xbt_test_add("Extended parmap usage (%u workers)", num_workers);
+
+    TEST_PARMAP_VALIDATE_MODE(mode);
+    parmap = xbt_parmap_new(num_workers, mode);
+
+    a = xbt_malloc(len * sizeof *a);
+    data = xbt_dynar_new(sizeof a, NULL);
+    for (i = 0; i < len; i++)
+      xbt_dynar_push_as(data, void *, &a[i]);
+
+    xbt_parmap_apply(parmap, fun_get_id, data);
+
+    qsort(a, len, sizeof a[0], fun_compare);
+    count = 1;
+    for (i = 1; i < len; i++)
+      if (a[i] != a[i - 1])
+        count++;
+    xbt_test_assert(count == num_workers,
+                    "only %u/%u threads did some work", count, num_workers);
+
+    xbt_dynar_free(&data);
+    xbt_free(a);
+    xbt_parmap_destroy(parmap);
   }
+}
 
-  for(i=0; i < 5; i++)
-    xbt_parmap_apply(parmap, fun, data);
+XBT_TEST_UNIT("extended_posix", test_parmap_extended_posix, "Extended usage: posix")
+{
+  test_parmap_extended(XBT_PARMAP_POSIX);
+}
+
+XBT_TEST_UNIT("extended_futex", test_parmap_extended_futex, "Extended usage: futex")
+{
+  test_parmap_extended(XBT_PARMAP_FUTEX);
+}
 
-  /* Destroy the parmap */
-  xbt_parmap_destroy(parmap);
-  xbt_dynar_free(&data);
+XBT_TEST_UNIT("extended_busy_wait", test_parmap_extended_busy_wait, "Extended usage: busy_wait")
+{
+  test_parmap_extended(XBT_PARMAP_BUSY_WAIT);
 }
 
 #endif /* SIMGRID_TEST */