sysdeps/x86_64/nptl/pthread_mutex_backoff.h

   1 /* Pthread mutex backoff configuration.
   2    Copyright (C) 2022-2023 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 #ifndef _PTHREAD_MUTEX_BACKOFF_H
  19 #define _PTHREAD_MUTEX_BACKOFF_H 1
  20
  21 #include <fast-jitter.h>
  22
  23 static inline unsigned int
  24 get_jitter (void)
  25 {
  26   return get_fast_jitter ();
  27 }
  28
  29 #define MAX_BACKOFF 16
  30
  31 static inline int
  32 get_next_backoff (int backoff)
  33 {
  34   /* Binary expontial backoff. Limiting max backoff
  35      can reduce latency in large critical section.  */
  36   return (backoff < MAX_BACKOFF) ? backoff << 1 : backoff;
  37 }
  38
  39 #endif