membar_ops(3) - NetBSD Manual Pages

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MEMBAR_OPS(3)           NetBSD Library Functions Manual          MEMBAR_OPS(3)


NAME

     membar_ops, membar_enter, membar_exit, membar_producer, membar_consumer,
     membar_sync -- memory access barrier operations


SYNOPSIS

     #include <sys/atomic.h>

     void
     membar_enter(void);

     void
     membar_exit(void);

     void
     membar_producer(void);

     void
     membar_consumer(void);

     void
     membar_sync(void);


DESCRIPTION

     The membar_ops family of functions provide memory access barrier opera-
     tions necessary for synchronization in multiprocessor execution environ-
     ments that have relaxed load and store order.

     membar_enter()

          Any store preceeding membar_enter() will reach global visibility
          before all loads and stores following it.

          membar_enter() is typically used in code that implements locking
          primitives to ensure that a lock protects its data.

     membar_exit()

          All loads and stores preceding membar_exit() will reach global visi-
          bility before any store that follows it.

          membar_exit() is typically used in code that implements locking
          primitives to ensure that a lock protects its data.

     membar_producer()

          All stores preceding the memory barrier will reach global visibility
          before any stores after the memory barrier reach global visibility.

     membar_consumer()

          All loads preceding the memory barrier will complete before any
          loads after the memory barrier complete.

     membar_sync()

          All loads and stores preceding the memory barrier will complete and
          reach global visibility before any loads and stores after the memory
          barrier complete and reach global visibility.


SEE ALSO

     atomic_ops(3)


HISTORY

     The membar_ops functions first appeared in NetBSD 5.0.

NetBSD 5.2                     Febuary 11, 2007                     NetBSD 5.2