DragonFly On-Line Manual Pages

CK_PR_FENCE_LOAD_ATOMIC(3)                  DragonFly Library Functions Manual

NAME
     ck_pr_fence_load_atomic - enforce ordering of load operations to atomic
     read-modify-write operations

LIBRARY
     Concurrency Kit (libck, -lck)

SYNOPSIS
     #include <ck_pr.h>

     void
     ck_pr_fence_load_atomic(void);

     void
     ck_pr_fence_strict_load_atomic(void);

DESCRIPTION
     This function enforces the ordering of any memory load and ck_pr_load(3)
     operations with respect to store operations relative to the invocation of
     the function. Any store operations that were committed on remote
     processors and received by the calling processor before the invocation of
     ck_pr_fence_load_atomic() is also be made visible only after a call to
     the ck_pr_fence_load family of functions.  This function always serves as
     an implicit compiler barrier.  On architectures with CK_MD_TSO or
     CK_MD_PSO specified (total store ordering and partial store ordering
     respectively), this operation only serves as a compiler barrier and no
     fence instructions will be emitted. To force the unconditional emission
     of a load fence, use ck_pr_fence_strict_load_atomic().  Architectures
     implementing CK_MD_RMO always emit a fence.

EXAMPLE

           #include <ck_pr.h>

           static unsigned int a;
           static unsigned int b;

           void
           function(void)
           {
                   unsigned int snapshot_a, snapshot_b;

                   snapshot_a = ck_pr_load_uint(&a);

                   /*
                    * Guarantee that the load from "a" completes
                    * before the update to "b".
                    */
                   ck_pr_fence_load_atomic();
                   ck_pr_fas_uint(&b, 1);

                   return;
           }

RETURN VALUES
     This function has no return value.

SEE ALSO
     ck_pr_stall(3), ck_pr_fence_atomic(3), ck_pr_fence_atomic_store(3),
     ck_pr_fence_atomic_load(3), ck_pr_fence_load_depends(3),
     ck_pr_fence_load_store(3), ck_pr_fence_store(3), ck_pr_fence_memory(3),
     ck_pr_barrier(3), ck_pr_fas(3), ck_pr_load(3), ck_pr_store(3),
     ck_pr_faa(3), ck_pr_inc(3), ck_pr_dec(3), ck_pr_neg(3), ck_pr_not(3),
     ck_pr_add(3), ck_pr_sub(3), ck_pr_and(3), ck_pr_or(3), ck_pr_xor(3),
     ck_pr_cas(3), ck_pr_btc(3), ck_pr_bts(3), ck_pr_btr(3)

     Additional information available at http://concurrencykit.org/

                                 May 18, 2013