| <html>
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| <head>
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| <title>shmem_long_add</title>
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| </head>
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| <h2 id="top">shmem_long_add</h2>
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| <h4>Purpose</h4>
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| <p>Performs an atomic add operation on 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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| void shmem_long_add(long *target, long value, int pe);
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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 remotely accessible integer data object to be updated on the PE.
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| </dd>
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| <dt class="bold ">value</dt>
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| <dd>Value to be atomically written to the target PE. Value is the same type as target.
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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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| <div class="ledi">
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| <p>The shmem_long_add routine performs an atomic add operation. </p>
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| <p>It adds value to the variable pointed by target on the processing element specified by pe.</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>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_fadd
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| </p>
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| <hr><a href="apiIndex.html">OpenSHMEM API Index</a> |
| </html> |
