nptl/pthread_mutex_conf.c

   1 /* Pthread mutex tunable parameters.
   2    Copyright (C) 2018-2019 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    <http://www.gnu.org/licenses/>.  */
  18
  19 #if HAVE_TUNABLES
  20 # define TUNABLE_NAMESPACE pthread
  21 #include <pthread_mutex_conf.h>
  22 #include <stdint.h>
  23 #include <stdbool.h>
  24 #include <unistd.h>  /* Get STDOUT_FILENO for _dl_printf.  */
  25 #include <elf/dl-tunables.h>
  26
  27 struct mutex_config __mutex_aconf =
  28 {
  29   /* The maximum number of times a thread should spin on the lock before
  30   calling into kernel to block.  */
  31   .spin_count = DEFAULT_ADAPTIVE_COUNT,
  32 };
  33
  34 static void
  35 TUNABLE_CALLBACK (set_mutex_spin_count) (tunable_val_t *valp)
  36 {
  37   __mutex_aconf.spin_count = (int32_t) (valp)->numval;
  38 }
  39
  40 void
  41 __pthread_tunables_init (void)
  42 {
  43   TUNABLE_GET (mutex_spin_count, int32_t,
  44                TUNABLE_CALLBACK (set_mutex_spin_count));
  45 }
  46 #endif