malloc/tst-mxfast.c

   1 /* Test that glibc.malloc.mxfast tunable works.
   2    Copyright (C) 2019-2024 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 /* This test verifies that setting the glibc.malloc.mxfast tunable to
  20    zero results in free'd blocks being returned to the small bins, not
  21    the fast bins.  */
  22
  23 #include <malloc.h>
  24 #include <libc-diag.h>
  25 #include <support/check.h>
  26
  27 int
  28 do_test (void)
  29 {
  30   struct mallinfo m;
  31   char *volatile p1;
  32   char *volatile p2;
  33
  34   /* Arbitrary value; must be in default fastbin range.  */
  35   p1 = malloc (3);
  36   /* Something large so that p1 isn't a "top block" */
  37   p2 = malloc (512);
  38   free (p1);
  39
  40   /* The test below covers the deprecated mallinfo function.  */
  41   DIAG_PUSH_NEEDS_COMMENT;
  42   DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wdeprecated-declarations");
  43
  44   m = mallinfo ();
  45
  46   DIAG_POP_NEEDS_COMMENT;
  47
  48   /* This will fail if there are any blocks in the fastbins.  */
  49   TEST_COMPARE (m.smblks, 0);
  50
  51   /* To keep gcc happy.  */
  52   free (p2);
  53
  54   return 0;
  55 }
  56
  57 #include <support/test-driver.c>