| <html>
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| <head>
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| <title>shmem_longlong_swap</title>
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| </head>
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| <h2 id="top">shmem_longlong_swap</h2>
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| <h4>Purpose</h4>
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| <p>Performs an atomic swap operation to a symmetric data object.
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| </p>
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| <h4>C syntax</h4>
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| <pre>
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| #include <shmem.h>
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|
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| long long shmem_longlong_swap(long long *target, long long value, int pe);
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|
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| </pre>
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| <h4>Parameters</h4>
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|
| <dl>
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| <dt class="bold">INPUT</dt>
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| <dd>
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| </dd>
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| <dt class="bold ">target</dt>
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| <dd>The pointer to the remotely accessible data object to be updated on
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| the remote PE.
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| </dd>
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| <dt class="bold ">value</dt>
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| <dd>The pointer to the remotely accessible data object to be updated on
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| the remote PE.
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| </dd>
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| <dt class="bold ">pe</dt>
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| <dd>An integer indicating the PE number on which target is to be
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| updated.
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| </dd>
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| </dl>
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| <h4>Description</h4>
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|
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| <div class="ledi">
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| <p>This function performs atomic swap operations</p>
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| <p>The shmem_longlong_swap function writes the long long value in to the variable pointed by
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| target on processing element pe and returns the previous contents of target as an
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| atomic operation.</p>
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| <p>The atomic accessing of the shared variable is guaranteed only when that variable is updated solely using IBM openshmem functions.</p>
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| <h4>Return values</h4>
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| <p>This function returns the contents that had been at the target address on the remote
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| PE prior to the swap is returned.</p>
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| <h4>IBM NOTES</h4>
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| <div class="ledi">
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| <dl>
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| <p>To utilize the hardware atomic operations support of the PERCS system, the variables of these operations should be aligned with their natural byte alignments. For example, an int variable should be 4-byte aligned; a long long variable should be 8-byte aligned. If the participating variables are not aligned, the operation is done in software with sub-optimal performance</p>
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| </dd>
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| </dl>
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| <h4>C examples</h4>
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| <pre>
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| </pre>
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| <h4>Related information</h4>
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| <p>Subroutines: shmem_put
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| </p>
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| <hr><a href="apiIndex.html">OpenSHMEM API Index</a> |
| </html> |
