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/