X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/c1fa53426d4f4db5c1fe697d915d30247fd5d09a..bc07ec1b28653016934209a9e84e249eebf703f0:/src/xbt/parmap.c

diff --git a/src/xbt/parmap.c b/src/xbt/parmap.c
index 0034d95f13..8a86b36384 100644
--- a/src/xbt/parmap.c
+++ b/src/xbt/parmap.c
@@ -3,172 +3,274 @@
 
 /* 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 "gras_config.h"
+#include <unistd.h>
 
-#include "parmap_private.h"
+#ifndef _XBT_WIN32
+#include <sys/syscall.h>
+#endif
+
+#ifdef HAVE_FUTEX_H
+#include <linux/futex.h>
+#endif
+
+#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 {
+  PARMAP_WORK = 0,
+  PARMAP_DESTROY
+} e_xbt_parmap_flag_t;
+
+static void xbt_parmap_start(xbt_parmap_t parmap);
+static void xbt_parmap_signal(xbt_parmap_t parmap);
+static void xbt_parmap_wait(xbt_parmap_t parmap);
+static void xbt_parmap_end(xbt_parmap_t parmap);
+static void *xbt_parmap_worker_main(void *parmap);
+
+#ifdef HAVE_FUTEX_H
+static void futex_wait(int *uaddr, int val);
+static void futex_wake(int *uaddr, int val);
+#endif
+
+/**
+ * \brief Parallel map structure
+ */
+typedef struct s_xbt_parmap {
+  e_xbt_parmap_flag_t status;      /* is the parmap active or being destroyed? */
+
+  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 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 */
+} s_xbt_parmap_t;
+
+/**
+ * \brief Creates a parallel map object
+ * \param num_workers number of worker threads to create
+ * \return the parmap created
+ */
 xbt_parmap_t xbt_parmap_new(unsigned int num_workers)
 {
   unsigned int i;
   xbt_os_thread_t worker = NULL;
 
-  DEBUG1("Create new parmap (%u workers)", num_workers);
+  XBT_DEBUG("Create new parmap (%u workers)", num_workers);
 
-  /* Initialize thread pool data structure */
+  /* Initialize the thread pool data structure */
   xbt_parmap_t parmap = xbt_new0(s_xbt_parmap_t, 1);
-  parmap->mutex = xbt_os_mutex_init();
-  parmap->job_posted = xbt_os_cond_init();
-  parmap->all_done = xbt_os_cond_init();
-  parmap->flags = xbt_new0(e_xbt_parmap_flag_t, num_workers + 1);
-  parmap->num_workers = num_workers;
-  parmap->num_idle_workers = 0;
-  parmap->workers_max_id = 0;
 
-  /* Init our flag to wait (for workers' initialization) */
-  parmap->flags[num_workers] = PARMAP_WAIT;
+  parmap->num_workers = num_workers;
+  parmap->status = PARMAP_WORK;
 
   /* 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 = 0; i < num_workers - 1; i++) {
+    worker = xbt_os_thread_create(NULL, xbt_parmap_worker_main, parmap, NULL);
     xbt_os_thread_detach(worker);
   }
-  
-  /* wait for the workers to initialize */
-  xbt_os_mutex_acquire(parmap->mutex);
-  while(parmap->flags[num_workers] == PARMAP_WAIT)
-    xbt_os_cond_wait(parmap->all_done, parmap->mutex);
-  xbt_os_mutex_release(parmap->mutex);
-
+  xbt_parmap_start(parmap);
   return parmap;
 }
 
+/**
+ * \brief Destroys a parmap
+ * \param parmap the parmap to destroy
+ */
 void xbt_parmap_destroy(xbt_parmap_t parmap)
-{ 
-  DEBUG1("Destroy parmap %p", parmap);
-
-  unsigned int i;
-
-  /* Lock the parmap, then signal every worker an wait for each to finish */
-  xbt_os_mutex_acquire(parmap->mutex);
-  for(i=0; i < parmap->num_workers; i++){
-    parmap->flags[i] = PARMAP_DESTROY;
-  }
-
-  xbt_os_cond_broadcast(parmap->job_posted);
-  while(parmap->num_workers){
-    DEBUG1("Still %u workers, waiting...", parmap->num_workers);
-    xbt_os_cond_wait(parmap->all_done, parmap->mutex);
-  }
-
-  /* Destroy pool's data structures */
-  xbt_os_cond_destroy(parmap->job_posted);
-  xbt_os_cond_destroy(parmap->all_done);
-  xbt_free(parmap->flags);
-  xbt_os_mutex_release(parmap->mutex);
-  xbt_os_mutex_destroy(parmap->mutex);
+{
+  parmap->status = PARMAP_DESTROY;
+  xbt_parmap_signal(parmap);
   xbt_free(parmap);
 }
 
+/**
+ * \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)
 {
-  unsigned int i;
-  unsigned int myflag_idx = parmap->num_workers;
-
   /* Assign resources to worker threads */
-  xbt_os_mutex_acquire(parmap->mutex);
   parmap->fun = fun;
   parmap->data = data;
-  parmap->num_idle_workers = 0;
+  parmap->index = 0;
+  xbt_parmap_signal(parmap);
+  XBT_DEBUG("Job done");
+}
 
-  /* Set worker flags to work */
-  for(i=0; i < parmap->num_workers; i++){
-    parmap->flags[i] = PARMAP_WORK;
+/**
+ * \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 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;
+}
 
-  /* Set our flag to wait (for the job to be completed)*/
-  parmap->flags[myflag_idx] = PARMAP_WAIT;
-
-  /* Notify workers that there is a job */
-  xbt_os_cond_broadcast(parmap->job_posted);
-  DEBUG0("Job dispatched, lets wait...");
+/**
+ * \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;
 
-  /* wait for the workers to finish */
-  while(parmap->flags[myflag_idx] == PARMAP_WAIT)
-    xbt_os_cond_wait(parmap->all_done, parmap->mutex);
+  XBT_DEBUG("New worker thread created");
 
-  DEBUG0("Job done");
-  parmap->fun = NULL;
-  parmap->data = NULL;
+  /* Worker's main loop */
+  while (1) {
+    xbt_parmap_wait(parmap);
+    if (parmap->status == PARMAP_WORK) {
 
-  xbt_os_mutex_release(parmap->mutex);    
-  return;
-}
+      XBT_DEBUG("Worker got a job");
 
-static void *_xbt_parmap_worker_main(void *arg)
-{
-  unsigned int data_start, data_end, data_size, worker_id;
-  xbt_parmap_t parmap = (xbt_parmap_t)arg;
+      void* work = xbt_parmap_next(parmap);
+      while (work != NULL) {
+        parmap->fun(work);
+        work = xbt_parmap_next(parmap);
+      }
 
-  /* Fetch a worker id */
-  xbt_os_mutex_acquire(parmap->mutex);
-  worker_id = parmap->workers_max_id++;
-  xbt_os_mutex_release(parmap->mutex);
+      XBT_DEBUG("Worker has finished");
 
-  DEBUG1("New worker thread created (%u)", worker_id);
-  
-  /* Worker's main loop */
-  while(1){
-    xbt_os_mutex_acquire(parmap->mutex);
-    parmap->flags[worker_id] = PARMAP_WAIT;
-    parmap->num_idle_workers++;
-
-    /* If everybody is done set the parmap work flag and signal it */
-    if(parmap->num_idle_workers == parmap->num_workers){
-      DEBUG1("Worker %u: All done, signal the parmap", worker_id);
-      parmap->flags[parmap->num_workers] = PARMAP_WORK;
-      xbt_os_cond_signal(parmap->all_done);
+    /* We are destroying the parmap */
+    } else {
+      xbt_parmap_end(parmap);
+      XBT_DEBUG("Shutting down worker");
+      return NULL;
     }
+  }
+}
 
-    /* If the wait flag is set then ... wait. */
-    while(parmap->flags[worker_id] == PARMAP_WAIT)
-      xbt_os_cond_wait(parmap->job_posted, parmap->mutex);
+#ifdef HAVE_FUTEX_H
+static void futex_wait(int *uaddr, int val)
+{
+  XBT_VERB("Waiting on futex %p", uaddr);
+  syscall(SYS_futex, uaddr, FUTEX_WAIT_PRIVATE, val, NULL, NULL, 0);
+}
 
-    DEBUG1("Worker %u got a job", worker_id);
+static void futex_wake(int *uaddr, int val)
+{
+  XBT_VERB("Waking futex %p", uaddr);
+  syscall(SYS_futex, uaddr, FUTEX_WAKE_PRIVATE, val, NULL, NULL, 0);
+}
+#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_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);
+  }
+#endif
+}
 
-    /* If we are shutting down, the last worker is going to signal the
-     * parmap so it can finish destroying the data structure */
-    if(parmap->flags[worker_id] == PARMAP_DESTROY){
-      DEBUG1("Shutting down worker %u", worker_id);
-      parmap->num_workers--;
-      if(parmap->num_workers == 0)
-        xbt_os_cond_signal(parmap->all_done);
-      xbt_os_mutex_release(parmap->mutex);
-      return NULL;
+/**
+ * \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_signal(xbt_parmap_t parmap)
+{
+#ifdef HAVE_FUTEX_H
+  int myflag = parmap->done;
+  parmap->thread_counter = 0;
+  parmap->work++;
+
+  /* wake all workers */
+  futex_wake(&parmap->work, parmap->num_workers);
+
+  if (parmap->status == PARMAP_WORK) {
+    /* also work myself */
+    void* work = xbt_parmap_next(parmap);
+    if (work != NULL) {
+      parmap->fun(work);
     }
-    xbt_os_mutex_release(parmap->mutex);
+  }
 
-    /* Compute how much data does every worker gets */
-    data_size = (xbt_dynar_length(parmap->data) / parmap->num_workers)
-                + ((xbt_dynar_length(parmap->data) % parmap->num_workers) ? 1 : 0);
+  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);
+  }
 
-    /* Each worker data segment starts in a position associated with its id*/
-    data_start = data_size * worker_id;
+#endif
+}
 
-    /* The end of the worker data segment must be bounded by the end of the data vector */
-    data_end = MIN(data_start + data_size, xbt_dynar_length(parmap->data));
+/**
+ * \brief Waits for some work to process.
+ *
+ * This function is called by each worker when it has no more work to do.
+ *
+ * \param parmap a parmap
+ */
+static void xbt_parmap_wait(xbt_parmap_t parmap)
+{
+#ifdef HAVE_FUTEX_H
+  int myflag;
+  unsigned int mycount;
+
+  myflag = parmap->work;
+  mycount = __sync_add_and_fetch(&parmap->thread_counter, 1);
+  if (mycount == parmap->num_workers) {
+    /* all workers have finished, wake the controller */
+    parmap->done++;
+    futex_wake(&parmap->done, 1);
+  }
 
-    DEBUG4("Worker %u: data_start=%u data_end=%u (data_size=%u)", worker_id, data_start, data_end, data_size);
+  /* wait for more work */
+  futex_wait(&parmap->work, myflag);
+#endif
+}
 
-    /* While the worker don't pass the end of it data segment apply the function */
-    while(data_start < data_end){
-      parmap->fun(*(void **)xbt_dynar_get_ptr(parmap->data, data_start));
-      data_start++;
-    }
+/**
+ * \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_end(xbt_parmap_t parmap)
+{
+#ifdef HAVE_FUTEX_H
+  unsigned int mycount;
+
+  mycount = __sync_add_and_fetch(&parmap->thread_counter, 1);
+  if (mycount == parmap->num_workers) {
+    /* all workers have finished, wake the controller */
+    parmap->done++;
+    futex_wake(&parmap->done, 1);
   }
+#endif
 }
 
 #ifdef SIMGRID_TEST
@@ -178,35 +280,36 @@ static void *_xbt_parmap_worker_main(void *arg)
 XBT_TEST_SUITE("parmap", "Parallel Map");
 XBT_LOG_EXTERNAL_DEFAULT_CATEGORY(xbt_parmap_unit);
 
-
-
 xbt_parmap_t parmap;
 
 void fun(void *arg);
 
 void fun(void *arg)
 {
-  INFO1("I'm job %lu", (unsigned long)arg);
+  //XBT_INFO("I'm job %lu", (unsigned long)arg);
 }
 
 XBT_TEST_UNIT("basic", test_parmap_basic, "Basic usage")
 {
-  xbt_test_add0("Create the parmap");
+  xbt_test_add("Create the parmap");
 
-  unsigned long j;
+  unsigned long i, j;
   xbt_dynar_t data = xbt_dynar_new(sizeof(void *), NULL);
 
   /* Create the parallel map */
-  parmap = xbt_parmap_new(5);
+  parmap = xbt_parmap_new(10);
 
-  for(j=0; j < 200; j++){
+  for (j = 0; j < 100; j++) {
     xbt_dynar_push_as(data, void *, (void *)j);
   }
 
-  xbt_parmap_apply(parmap, fun, data);
+  for (i = 0; i < 5; i++) {
+    xbt_parmap_apply(parmap, fun, data);
+  }
 
   /* Destroy the parmap */
   xbt_parmap_destroy(parmap);
+  xbt_dynar_free(&data);
 }
 
 #endif /* SIMGRID_TEST */