Added examples/threads.c (and updated Makefile.am): multithreading test

to detect scaling issues with MPFR.

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@12943 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 90 insertions, 0 deletions

diff --git a/examples/threads.c b/examples/threads.c
new file mode 100644
index 000000000..4fccd1a21
--- /dev/null
+++ b/examples/threads.c
@@ -0,0 +1,90 @@
+/* Multithreading test to detect scaling issues with MPFR.
+
+Define:
+  * the function F;
+  * the precision PREC;
+  * the value V as an expression that will have the type double
+    (it may depend on the thread number i).
+
+Example:
+  gcc threads.c -lmpfr -lgmp -lpthread -DF=mpfr_sin -DPREC=200 -DV=100
+
+Copyright 2018 Free Software Foundation, Inc.
+Contributed by the AriC and Caramba projects, INRIA.
+
+This file is part of the GNU MPFR Library.
+
+The GNU MPFR Library is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 3 of the License, or (at your
+option) any later version.
+
+The GNU MPFR Library 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 Lesser General Public
+License for more details.
+
+You should have received a copy of the GNU Lesser General Public License
+along with the GNU MPFR Library; see the file COPYING.LESSER.  If not, see
+http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
+51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <pthread.h>
+
+#include <mpfr.h>
+
+#define MAX_THREADS 256
+
+static int m;
+
+static void *start_routine (void *arg)
+{
+  mpfr_t x, y;
+  int i = *(int *) arg, j;
+
+  (void) i;  /* avoid a warning if i is not used by V */
+
+  mpfr_inits2 (PREC, x, y, (mpfr_ptr) 0);
+  mpfr_set_d (x, (V), MPFR_RNDN);
+
+  for (j = 0; j < m; j++)
+    F (y, x, MPFR_RNDN);
+
+  mpfr_clears (x, y, (mpfr_ptr) 0);
+  pthread_exit (NULL);
+}
+
+int main (int argc, char *argv[])
+{
+  int i, n;
+  pthread_t tid[MAX_THREADS];
+
+  if (argc != 3 ||
+      (m = atoi (argv[1]), m < 1) ||
+      (n = atoi (argv[2]), n < 1 || n > MAX_THREADS))
+    {
+      fprintf (stderr, "Usage: %s <#iterations> <#threads>\n", argv[0]);
+      exit (1);
+    }
+
+  printf ("%d iteration(s), %d thread(s).\n", m, n);
+
+  for (i = 0; i < n; i++)
+    if (pthread_create (&tid[i], NULL, start_routine, &i) != 0)
+      {
+        fprintf (stderr, "%s: failed to create thread %d\n", argv[0], i);
+        exit (1);
+      }
+
+  for (i = 0; i < n; i++)
+    if (pthread_join (tid[i], NULL) != 0)
+      {
+        fprintf (stderr, "%s: failed to join thread %d\n", argv[0], i);
+        exit (1);
+      }
+
+  return 0;
+}