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