Parmap: make maestro also do some work.

[simgrid.git] / src / xbt / parmap.c

diff --git a/src/xbt/parmap.c b/src/xbt/parmap.c
index 25de341..4e79b71 100644 (file)
--- a/src/xbt/parmap.c
+++ b/src/xbt/parmap.c
@@ -49,8 +49,7 @@ typedef struct s_xbt_parmap {
   int work;                        /* index of the current round (1 is the first) */
   int done;                        /* number of rounds already done */
   unsigned int thread_counter;     /* number of threads currently working */
-  unsigned int num_workers;        /* total number of worker threads */
-  unsigned int workers_max_id;     /* id of the next worker thread to create */
+  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 */
@@ -75,7 +74,7 @@ xbt_parmap_t xbt_parmap_new(unsigned int num_workers)
   parmap->status = PARMAP_WORK;
 
   /* Create the pool of worker threads */
-  for (i = 0; i < num_workers; i++) {
+  for (i = 0; i < num_workers - 1; i++) {
     worker = xbt_os_thread_create(NULL, xbt_parmap_worker_main, parmap, NULL);
     xbt_os_thread_detach(worker);
   }
@@ -102,7 +101,7 @@ void xbt_parmap_destroy(xbt_parmap_t parmap)
  */
 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;
@@ -126,49 +125,34 @@ void* xbt_parmap_next(xbt_parmap_t parmap)
   return NULL;
 }
 
-/**
- * \brief Returns the worker id of the current thread.
- * \param parmap a parmap
- * \return the worker id
- */
-unsigned long xbt_parmap_get_worker_id(xbt_parmap_t parmap)
-{
-  return (unsigned long) xbt_os_thread_get_extra_data();
-}
-
 /**
  * \brief Main function of a worker thread.
  * \param arg the parmap
  */
 static void *xbt_parmap_worker_main(void *arg)
 {
-  unsigned int worker_id;
   xbt_parmap_t parmap = (xbt_parmap_t) arg;
 
-  /* 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);
+  XBT_DEBUG("New worker thread created");
 
-  XBT_DEBUG("New worker thread created (%u)", worker_id);
-  
   /* Worker's main loop */
   while (1) {
     xbt_parmap_wait(parmap);
     if (parmap->status == PARMAP_WORK) {
 
-      XBT_DEBUG("Worker %u got a job", worker_id);
+      XBT_DEBUG("Worker got a job");
 
       void* work = xbt_parmap_next(parmap);
       if (work != NULL) {
         parmap->fun(work);
       }
 
-      XBT_DEBUG("Worker %u has finished", worker_id);
+      XBT_DEBUG("Worker has finished");
 
     /* We are destroying the parmap */
     } else {
       xbt_parmap_end(parmap);
-      XBT_DEBUG("Shutting down worker %u", worker_id);
+      XBT_DEBUG("Shutting down worker");
       return NULL;
     }
   }
@@ -199,6 +183,7 @@ static void xbt_parmap_start(xbt_parmap_t parmap)
 {
 #ifdef HAVE_FUTEX_H
   int myflag = parmap->done;
+  __sync_fetch_and_add(&parmap->thread_counter, 1);
   if (parmap->thread_counter < parmap->num_workers) {
     /* wait for all workers to be ready */
     futex_wait(&parmap->done, myflag);
@@ -223,8 +208,20 @@ static void xbt_parmap_signal(xbt_parmap_t parmap)
   /* wake all workers */
   futex_wake(&parmap->work, parmap->num_workers);
 
-  /* wait for all of them to finish */
-  futex_wait(&parmap->done, myflag);
+  if (parmap->status == PARMAP_WORK) {
+    /* also work myself */
+    void* work = xbt_parmap_next(parmap);
+    if (work != NULL) {
+      parmap->fun(work);
+    }
+  }
+
+  unsigned int mycount = __sync_add_and_fetch(&parmap->thread_counter, 1);
+  if (mycount < parmap->num_workers) {
+    /* some workers have not finished yet */
+    futex_wait(&parmap->done, myflag);
+  }
+
 #endif
 }
 
@@ -301,7 +298,7 @@ XBT_TEST_UNIT("basic", test_parmap_basic, "Basic usage")
   /* Create the parallel map */
   parmap = xbt_parmap_new(10);
 
-  for(j = 0; j < 100; j++) {
+  for (j = 0; j < 100; j++) {
     xbt_dynar_push_as(data, void *, (void *)j);
   }