mcs-queue/backoff.c

   1 extern unsigned backoff;
   2 extern unsigned backoff_base_bits;
   3 extern unsigned backoff_cap_bits;
   4 extern unsigned backoff_shift_bits;
   5 extern unsigned backoff_base;
   6 extern unsigned backoff_cap;
   7 extern unsigned backoff_addend;
   8
   9 void init_backoff()
  10 {
  11         backoff_base = (1<<backoff_base_bits)-1;
  12         backoff_cap = (1<<backoff_cap_bits)-1;
  13         backoff_addend = (1<<backoff_shift_bits)-1;
  14 }
  15
  16 unsigned backoff_delay()
  17 {
  18         unsigned i;
  19
  20         for (i=0; i<backoff; i++) ;
  21         backoff <<= backoff_shift_bits;
  22         backoff += backoff_addend;
  23         backoff &= backoff_cap;
  24         return i;
  25 }