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@@ -760,6 +760,34 @@ not matter.
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The example <c>examples/pi</c> uses scratches for some temporary buffer.
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+\section ChangingDataSize Changing the size of a data
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+
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+The size of the output of a task may not be known in advance. In such a case,
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+a task can dynamically allocate or even reallocate the data. An example can
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+be found in tests/datawizard/variable_size.c . The example uses its own data
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+interface so as to contain some simulation information for data growth, but the
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+principle can be applied for any data interface.
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+
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+The principle is to use <c>starpu_malloc_on_node_flags</c> to make the new
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+allocation, and use <c>starpu_free_on_node_flags</c> to release any previous
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+allocation. The flags have to be precisely like in the example:
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+
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+\code{.c}
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+unsigned workerid = starpu_worker_get_id_check();
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+unsigned dst_node = starpu_worker_get_memory_node(workerid);
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+interface->ptr = starpu_malloc_on_node_flags(dst_node, size + increase, STARPU_MALLOC_PINNED | STARPU_MALLOC_COUNT | STARPU_MEMORY_OVERFLOW);
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+starpu_free_on_node_flags(dst_node, old, size, STARPU_MALLOC_PINNED | STARPU_MALLOC_COUNT | STARPU_MEMORY_OVERFLOW);
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+interface->size += increase;
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+\endcode
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+
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+so that the allocated area has the expected properties and the allocation is accounted for properly.
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+
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+Depending on the interface (vector, CSR, etc.) you may have to fix several
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+members of the data interface: e.g. both nx and allocsize for vectors, and store
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+the pointer both in ptr and dev_handle.
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+
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+Important note: one can not change the size of a partitioned data.
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+
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\section TheMultiformatInterface The Multiformat Interface
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It may be interesting to represent the same piece of data using two different
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