contrib/jemalloc/include/jemalloc/internal/spin.h

   1 #ifndef JEMALLOC_INTERNAL_SPIN_H
   2 #define JEMALLOC_INTERNAL_SPIN_H
   3
   4 #define SPIN_INITIALIZER {0U}
   5
   6 typedef struct {
   7         unsigned iteration;
   8 } spin_t;
   9
  10 static inline void
  11 spin_cpu_spinwait() {
  12 #  if HAVE_CPU_SPINWAIT
  13         CPU_SPINWAIT;
  14 #  else
  15         volatile int x = 0;
  16         x = x;
  17 #  endif
  18 }
  19
  20 static inline void
  21 spin_adaptive(spin_t *spin) {
  22         volatile uint32_t i;
  23
  24         if (spin->iteration < 5) {
  25                 for (i = 0; i < (1U << spin->iteration); i++) {
  26                         spin_cpu_spinwait();
  27                 }
  28                 spin->iteration++;
  29         } else {
  30 #ifdef _WIN32
  31                 SwitchToThread();
  32 #else
  33                 sched_yield();
  34 #endif
  35         }
  36 }
  37
  38 #undef SPIN_INLINE
  39
  40 #endif /* JEMALLOC_INTERNAL_SPIN_H */