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<compounddef id="SingleTaskCUDA" kind="page">

<compoundname>SingleTaskCUDA</compoundname>

<title>Single Task</title>

<tableofcontents/>

<briefdescription>

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<detaileddescription>

<para><ref refid="classtf_1_1cudaFlow" kindref="compound">tf::cudaFlow</ref> provides a template method, <ref refid="classtf_1_1cudaFlow_1ac2906cb0002fc411a983d100a3d58d62" kindref="member">tf::cudaFlow::single_task</ref>, for creating a task to run the given callable using a single kernel thread.</para><sect1 id="SingleTaskCUDA_1CUDASingleTaskIncludeTheHeader">

<title>Include the Header</title>

<para>You need to include the header file, <computeroutput>taskflow/cuda/algorithm/for_each.hpp</computeroutput>, for creating a single-threaded task.</para><para><programlisting filename=".cpp"><codeline><highlight class="preprocessor">#include<sp/>&lt;<ref refid="for__each_8hpp" kindref="compound">taskflow/cuda/algorithm/for_each.hpp</ref>&gt;</highlight></codeline>

</programlisting></para></sect1>

<sect1 id="SingleTaskCUDA_1SingleTaskCUDASingleTask">

<title>Run a Task with a Single Thread</title>

<para>You can create a task to run a kernel function just once, i.e., using one GPU thread. This is handy when you want to set up a single or a few global variables that do not need multiple threads and will be used by multiple kernels afterwards. The following example creates a single-task kernel that sets a device variable to <computeroutput>1</computeroutput>.</para><para><programlisting filename=".cpp"><codeline><highlight class="keywordtype">int</highlight><highlight class="normal">*<sp/>gpu_variable;</highlight></codeline>

<codeline><highlight class="normal">cudaMalloc(&amp;gpu_variable,<sp/></highlight><highlight class="keyword">sizeof</highlight><highlight class="normal">(</highlight><highlight class="keywordtype">int</highlight><highlight class="normal">));</highlight></codeline>

<codeline><highlight class="normal"></highlight></codeline>

<codeline><highlight class="normal"><ref refid="classtf_1_1cudaFlow" kindref="compound">tf::cudaFlow</ref><sp/>cf;</highlight></codeline>

<codeline><highlight class="normal">cf.<ref refid="classtf_1_1cudaFlow_1ac2906cb0002fc411a983d100a3d58d62" kindref="member">single_task</ref>([gpu_variable]<sp/>__device__<sp/>()<sp/>{</highlight></codeline>

<codeline><highlight class="normal"><sp/><sp/>*gpu_Variable<sp/>=<sp/>1;</highlight></codeline>

<codeline><highlight class="normal">});</highlight></codeline>

<codeline><highlight class="normal"></highlight></codeline>

<codeline><highlight class="normal"><ref refid="classtf_1_1cudaStream" kindref="compound">tf::cudaStream</ref><sp/>stream;</highlight></codeline>

<codeline><highlight class="normal">cf.<ref refid="classtf_1_1cudaFlow_1ae6810f7de27e5a347331aacfce67bea1" kindref="member">run</ref>(stream);</highlight></codeline>

<codeline><highlight class="normal">stream.<ref refid="classtf_1_1cudaStream_1a1a81d6005e8d60ad082dba2303a8aa30" kindref="member">synchronize</ref>();</highlight></codeline>

</programlisting></para><para>Since the callable runs on GPU, it must be declared with a <computeroutput>__device__</computeroutput> specifier.</para></sect1>

<sect1 id="SingleTaskCUDA_1SingleTaskCUDAMiscellaneousItems">

<title>Miscellaneous Items</title>

<para>The single-task algorithm is also available in <ref refid="classtf_1_1cudaFlowCapturer_1ac944c7d20056e0633ef84f1a25b52296" kindref="member">tf::cudaFlowCapturer::single_task</ref>. </para></sect1>

</detaileddescription>

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