161 lines
6.8 KiB
HTML
161 lines
6.8 KiB
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<title>num_cpus - Rust</title>
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<p class='location'>Crate num_cpus</p><div class="sidebar-elems"><div class="block items"><ul><li><a href="#functions">Functions</a></li></ul></div><p class='location'></p><script>window.sidebarCurrent = {name: 'num_cpus', ty: 'mod', relpath: '../'};</script></div>
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<section id='main' class="content"><h1 class='fqn'><span class='in-band'>Crate <a class="mod" href=''>num_cpus</a></span><span class='out-of-band'><span id='render-detail'>
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[<span class='inner'>−</span>]
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</span><a class='srclink' href='../src/num_cpus/lib.rs.html#1-414' title='goto source code'>[src]</a></span></h1><div class='docblock'><p>A crate with utilities to determine the number of CPUs available on the
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current system.</p>
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<p>Sometimes the CPU will exaggerate the number of CPUs it contains, because it can use
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<a href="https://en.wikipedia.org/wiki/Simultaneous_multithreading">processor tricks</a> to deliver increased performance when there are more threads. This
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crate provides methods to get both the logical and physical numbers of cores.</p>
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<p>This information can be used as a guide to how many tasks can be run in parallel.
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There are many properties of the system architecture that will affect parallelism,
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for example memory access speeds (for all the caches and RAM) and the physical
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architecture of the processor, so the number of CPUs should be used as a rough guide
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only.</p>
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<h2 id="examples" class="section-header"><a href="#examples">Examples</a></h2>
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<p>Fetch the number of logical CPUs.</p>
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<pre class="rust rust-example-rendered">
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<span class="kw">let</span> <span class="ident">cpus</span> <span class="op">=</span> <span class="ident">num_cpus</span>::<span class="ident">get</span>();</pre>
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<p>See <a href="https://docs.rs/rayon/0.8.2/rayon/struct.ThreadPool.html"><code>rayon::Threadpool</code></a> for an example of where the number of CPUs could be
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used when setting up parallel jobs (Where the threadpool example uses a fixed
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number 8, it could use the number of CPUs).</p>
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</div><h2 id='functions' class='section-header'><a href="#functions">Functions</a></h2>
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<table>
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<tr class=' module-item'>
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<td><a class="fn" href="fn.get.html"
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title='fn num_cpus::get'>get</a></td>
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<td class='docblock-short'>
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<p>Returns the number of available CPUs of the current system.</p>
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</td>
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</tr>
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<tr class=' module-item'>
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<td><a class="fn" href="fn.get_physical.html"
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title='fn num_cpus::get_physical'>get_physical</a></td>
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<td class='docblock-short'>
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<p>Returns the number of physical cores of the current system.</p>
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</td>
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</tr></table></section>
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