[gomp] Thread pool management

libgomp/ChangeLog

	* config/posix/pool.h: New.
	* config/rtems/pool.h: Likewise.
	* config/rtems/proc.c: Likewise.
	* libgomp.h (gomp_thread_destructor): Declare.
	* team.c: Include configuration provided "pool.h".
	(gomp_get_thread_pool): Define in configuration.
	(gomp_team_end): Call configuration defined
	gomp_release_thread_pool().

From-SVN: r227441

libgomp/ChangeLog

 2015-09-03  Sebastian Huber  <sebastian.huber@embedded-brains.de>
 
+	* config/posix/pool.h: New.
+	* config/rtems/pool.h: Likewise.
+	* config/rtems/proc.c: Likewise.
+	* libgomp.h (gomp_thread_destructor): Declare.
+	* team.c: Include configuration provided "pool.h".
+	(gomp_get_thread_pool): Define in configuration.
+	(gomp_team_end): Call configuration defined
+	gomp_release_thread_pool().
+
+2015-09-03  Sebastian Huber  <sebastian.huber@embedded-brains.de>
+
 	* config/rtems/bar.c: New.
 	* config/rtems/bar.h: Likewise.
 	* config/rtems/mutex.c: Likewise.

libgomp/config/posix/pool.h

+/* Copyright (C) 2005-2015 Free Software Foundation, Inc.
+   Contributed by Sebastian Huber <sebastian.huber@embedded-brains.de>.
+
+   This file is part of the GNU Offloading and Multi Processing Library
+   (libgomp).
+
+   Libgomp is free software; you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3, or (at your option)
+   any later version.
+
+   Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
+   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+   FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+   more details.
+
+   Under Section 7 of GPL version 3, you are granted additional
+   permissions described in the GCC Runtime Library Exception, version
+   3.1, as published by the Free Software Foundation.
+
+   You should have received a copy of the GNU General Public License and
+   a copy of the GCC Runtime Library Exception along with this program;
+   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* This is the default implementation of the thread pool management
+   for libgomp.  This type is private to the library.  */
+
+#ifndef GOMP_POOL_H
+#define GOMP_POOL_H 1
+
+#include "libgomp.h"
+
+/* Get the thread pool, allocate and initialize it on demand.  */
+
+static inline struct gomp_thread_pool *
+gomp_get_thread_pool (struct gomp_thread *thr, unsigned nthreads)
+{
+  struct gomp_thread_pool *pool = thr->thread_pool;
+  if (__builtin_expect (pool == NULL, 0))
+    {
+      pool = gomp_malloc (sizeof (*pool));
+      pool->threads = NULL;
+      pool->threads_size = 0;
+      pool->threads_used = 0;
+      pool->last_team = NULL;
+      pool->threads_busy = nthreads;
+      thr->thread_pool = pool;
+      pthread_setspecific (gomp_thread_destructor, thr);
+    }
+  return pool;
+}
+
+static inline void
+gomp_release_thread_pool (struct gomp_thread_pool *pool)
+{
+  /* Do nothing in the default implementation.  */
+}
+
+#endif /* GOMP_POOL_H */

libgomp/config/rtems/pool.h

+/* Copyright (C) 2015 Free Software Foundation, Inc.
+   Contributed by Sebastian Huber <sebastian.huber@embedded-brains.de>.
+
+   This file is part of the GNU Offloading and Multi Processing Library
+   (libgomp).
+
+   Libgomp is free software; you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3, or (at your option)
+   any later version.
+
+   Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
+   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+   FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+   more details.
+
+   Under Section 7 of GPL version 3, you are granted additional
+   permissions described in the GCC Runtime Library Exception, version
+   3.1, as published by the Free Software Foundation.
+
+   You should have received a copy of the GNU General Public License and
+   a copy of the GCC Runtime Library Exception along with this program;
+   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* This is the RTEMS implementation of the thread pool management
+   for libgomp.  This type is private to the library.  */
+
+#ifndef GOMP_POOL_H
+#define GOMP_POOL_H 1
+
+#include "libgomp.h"
+#include <sys/lock.h>
+#include <string.h>
+
+/* For each scheduler instance there may be a thread pool reservoir
+   to limit the number of thread pools used by the OpenMP master threads of this
+   scheduler instance.  The reservoirs are configured via the
+   GOMP_RTEMS_THREAD_POOLS environment variable.  */
+struct gomp_thread_pool_reservoir {
+  gomp_sem_t available;
+  gomp_mutex_t lock;
+  size_t index;
+  struct gomp_thread_pool *pools[];
+};
+
+struct gomp_tls_rtems_data {
+  struct gomp_thread_pool_reservoir *thread_pool_reservoir;
+};
+
+extern struct gomp_thread_pool_reservoir **gomp_thread_pool_reservoirs;
+
+extern __thread struct gomp_tls_rtems_data gomp_tls_rtems_data;
+
+static inline struct gomp_thread_pool_reservoir *
+gomp_get_thread_pool_reservoir (void)
+{
+  struct gomp_thread_pool_reservoir *res =
+    gomp_tls_rtems_data.thread_pool_reservoir;
+
+  if (res == NULL && gomp_thread_pool_reservoirs != NULL)
+    {
+      struct gomp_thread *thr = gomp_thread ();
+      thr->thread_pool = gomp_malloc_cleared (sizeof (*thr->thread_pool));
+      res = gomp_thread_pool_reservoirs[_Sched_Index ()];
+      gomp_tls_rtems_data.thread_pool_reservoir = res;
+    }
+
+  return res;
+}
+
+static inline struct gomp_thread_pool *
+gomp_get_own_thread_pool (struct gomp_thread *thr, unsigned nthreads)
+{
+  struct gomp_thread_pool *pool = thr->thread_pool;
+  if (__builtin_expect (pool == NULL, 0))
+    {
+      pool = gomp_malloc_cleared (sizeof (*pool));
+      pool->threads_busy = nthreads;
+      thr->thread_pool = pool;
+    }
+  return pool;
+}
+
+static inline struct gomp_thread_pool *
+gomp_get_thread_pool (struct gomp_thread *thr, unsigned nthreads)
+{
+  struct gomp_thread_pool *pool;
+
+  if (__builtin_expect (thr->thread_pool == NULL, 0))
+    pthread_setspecific (gomp_thread_destructor, thr);
+
+  if (nthreads != 1)
+    {
+      struct gomp_thread_pool_reservoir *res =
+	gomp_get_thread_pool_reservoir ();
+      if (res != NULL)
+	{
+	  gomp_sem_wait (&res->available);
+	  gomp_mutex_lock (&res->lock);
+	  pool = res->pools[--res->index];
+	  gomp_mutex_unlock (&res->lock);
+	  pool->threads_busy = nthreads;
+	  thr->thread_pool = pool;
+	}
+      else
+	pool = gomp_get_own_thread_pool (thr, nthreads);
+    }
+  else
+    pool = NULL;
+  return pool;
+}
+
+static inline void
+gomp_release_thread_pool (struct gomp_thread_pool *pool)
+{
+  struct gomp_thread_pool_reservoir *res =
+    gomp_tls_rtems_data.thread_pool_reservoir;
+  if (res != NULL)
+    {
+      gomp_mutex_lock (&res->lock);
+      res->pools[res->index++] = pool;
+      gomp_mutex_unlock (&res->lock);
+      gomp_sem_post (&res->available);
+    }
+}
+
+#endif /* GOMP_POOL_H */

libgomp/config/rtems/proc.c

+/* Copyright (C) 2015 Free Software Foundation, Inc.
+   Contributed by Sebastian Huber <sebastian.huber@embedded-brains.de>.
+
+   This file is part of the GNU Offloading and Multi Processing Library
+   (libgomp).
+
+   Libgomp is free software; you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3, or (at your option)
+   any later version.
+
+   Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
+   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+   FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+   more details.
+
+   Under Section 7 of GPL version 3, you are granted additional
+   permissions described in the GCC Runtime Library Exception, version
+   3.1, as published by the Free Software Foundation.
+
+   You should have received a copy of the GNU General Public License and
+   a copy of the GCC Runtime Library Exception along with this program;
+   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* This file contains RTEMS specific routines related to counting
+   online processors and dynamic load balancing.  */
+
+#include "libgomp.h"
+#include "pool.h"
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+struct gomp_thread_pool_reservoir **gomp_thread_pool_reservoirs;
+
+__thread struct gomp_tls_rtems_data gomp_tls_rtems_data;
+
+static void
+allocate_thread_pool_reservoirs (void)
+{
+  struct gomp_thread_pool_reservoir **reservoirs;
+  size_t size = _Sched_Count () * sizeof (*reservoirs);
+  reservoirs = gomp_malloc (size);
+  gomp_thread_pool_reservoirs = reservoirs;
+  memset (reservoirs, 0, size);
+}
+
+static void
+allocate_thread_pool_reservoir (unsigned long count, unsigned long scheduler)
+{
+  struct gomp_thread_pool_reservoir *res;
+  struct gomp_thread_pool *pools;
+  unsigned long i;
+  size_t size;
+
+  res = gomp_thread_pool_reservoirs[scheduler];
+  if (res != NULL)
+    gomp_fatal ("Multiple thread pool reservoir initialization");
+  size = sizeof (*res) + count * (sizeof(pools) + sizeof(*pools));
+  pools = gomp_malloc (size);
+  memset (pools, 0, size);
+  res = (struct gomp_thread_pool_reservoir *) (pools + count);
+  res->index = count;
+  gomp_sem_init (&res->available, count);
+  gomp_mutex_init (&res->lock);
+  for (i = 0; i < count; ++i)
+    res->pools[i] = &pools[i];
+  gomp_thread_pool_reservoirs[scheduler] = res;
+}
+
+static char *
+parse_thread_pools (char *env, unsigned long *count, unsigned long *scheduler)
+{
+  size_t len;
+  int i;
+
+  if (*env == ':')
+    ++env;
+
+  errno = 0;
+  *count = strtoul (env, &env, 10);
+  if (errno != 0)
+    gomp_fatal ("Invalid thread pool count");
+
+  if (*env != '@')
+    gomp_fatal ("Invalid thread pool scheduler prefix");
+  ++env;
+
+  len = 0;
+  while (env[len] != '\0' && env[len] != ':')
+    ++len;
+  i = _Sched_Name_to_index (env, len);
+  if (i < 0)
+    gomp_fatal ("Invalid thread pool scheduler");
+  *scheduler = i;
+  env += len;
+
+  return env;
+}
+
+static void
+init_thread_pool_reservoirs (void)
+{
+  char *env = getenv ("GOMP_RTEMS_THREAD_POOLS");
+  if (env != NULL)
+    {
+      allocate_thread_pool_reservoirs ();
+      while (*env != '\0')
+	{
+	  unsigned long count;
+	  unsigned long scheduler;
+	  env = parse_thread_pools (env, &count, &scheduler);
+	  allocate_thread_pool_reservoir (count, scheduler);
+	}
+    }
+}
+
+void
+gomp_init_num_threads (void)
+{
+  gomp_global_icv.nthreads_var = omp_get_num_procs();
+  init_thread_pool_reservoirs ();
+}
+
+unsigned
+gomp_dynamic_max_threads (void)
+{
+  unsigned n_onln = (unsigned) omp_get_num_procs();
+  unsigned nthreads_var = gomp_icv (false)->nthreads_var;
+
+  if (n_onln > nthreads_var)
+    return nthreads_var;
+  else
+    return n_onln;
+}
+
+int
+omp_get_num_procs (void)
+{
+  return sysconf (_SC_NPROCESSORS_ONLN);
+}
+
+ialias (omp_get_num_procs)

libgomp/libgomp.h

@@ -513,6 +513,8 @@ static inline struct gomp_task_icv *gomp_icv (bool write)
 /* The attributes to be used during thread creation.  */
 extern pthread_attr_t gomp_thread_attr;
 
+extern pthread_key_t gomp_thread_destructor;
+
 /* Function prototypes.  */
 
 /* affinity.c */

libgomp/team.c

@@ -27,6 +27,7 @@
    creation and termination.  */
 
 #include "libgomp.h"
+#include "pool.h"
 #include <stdlib.h>
 #include <string.h>
 
@@ -134,26 +135,6 @@ gomp_thread_start (void *xdata)
   return NULL;
 }
 
-/* Get the thread pool, allocate and initialize it on demand.  */
-
-static inline struct gomp_thread_pool *
-gomp_get_thread_pool (struct gomp_thread *thr, unsigned nthreads)
-{
-  struct gomp_thread_pool *pool = thr->thread_pool;
-  if (__builtin_expect (pool == NULL, 0))
-    {
-      pool = gomp_malloc (sizeof (*pool));
-      pool->threads = NULL;
-      pool->threads_size = 0;
-      pool->threads_used = 0;
-      pool->last_team = NULL;
-      pool->threads_busy = nthreads;
-      thr->thread_pool = pool;
-      pthread_setspecific (gomp_thread_destructor, thr);
-    }
-  return pool;
-}
-
 static inline struct gomp_team *
 get_last_team (unsigned nthreads)
 {
@@ -930,6 +911,7 @@ gomp_team_end (void)
       if (pool->last_team)
 	free_team (pool->last_team);
       pool->last_team = team;
+      gomp_release_thread_pool (pool);
     }
 }