18 lines
4.8 KiB
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18 lines
4.8 KiB
HTML
<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="A crate with utilities to determine the number of CPUs available on the current system."><title>num_cpus - Rust</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-6b053e98.ttf.woff2,FiraSans-Regular-0fe48ade.woff2,FiraSans-Medium-e1aa3f0a.woff2,SourceCodePro-Regular-8badfe75.ttf.woff2,SourceCodePro-Semibold-aa29a496.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../static.files/normalize-9960930a.css"><link rel="stylesheet" href="../static.files/rustdoc-42caa33d.css"><meta name="rustdoc-vars" data-root-path="../" data-static-root-path="../static.files/" data-current-crate="num_cpus" data-themes="" data-resource-suffix="" data-rustdoc-version="1.84.0 (9fc6b4312 2025-01-07)" data-channel="1.84.0" data-search-js="search-92e6798f.js" data-settings-js="settings-0f613d39.js" ><script src="../static.files/storage-59e33391.js"></script><script defer src="../crates.js"></script><script defer src="../static.files/main-5f194d8c.js"></script><noscript><link rel="stylesheet" href="../static.files/noscript-893ab5e7.css"></noscript><link rel="alternate icon" type="image/png" href="../static.files/favicon-32x32-6580c154.png"><link rel="icon" type="image/svg+xml" href="../static.files/favicon-044be391.svg"></head><body class="rustdoc mod crate"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="mobile-topbar"><button class="sidebar-menu-toggle" title="show sidebar"></button></nav><nav class="sidebar"><div class="sidebar-crate"><h2><a href="../num_cpus/index.html">num_<wbr>cpus</a><span class="version">1.16.0</span></h2></div><div class="sidebar-elems"><ul class="block"><li><a id="all-types" href="all.html">All Items</a></li></ul><section id="rustdoc-toc"><h3><a href="#">Sections</a></h3><ul class="block top-toc"><li><a href="#examples" title="Examples">Examples</a></li></ul><h3><a href="#functions">Crate Items</a></h3><ul class="block"><li><a href="#functions" title="Functions">Functions</a></li></ul></section><div id="rustdoc-modnav"></div></div></nav><div class="sidebar-resizer"></div><main><div class="width-limiter"><rustdoc-search></rustdoc-search><section id="main-content" class="content"><div class="main-heading"><h1>Crate <span>num_cpus</span><button id="copy-path" title="Copy item path to clipboard">Copy item path</button></h1><rustdoc-toolbar></rustdoc-toolbar><span class="sub-heading"><a class="src" href="../src/num_cpus/lib.rs.html#1-485">Source</a> </span></div><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><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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<h3 id="examples"><a class="doc-anchor" href="#examples">§</a>Examples</h3>
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<p>Fetch the number of logical CPUs.</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">let </span>cpus = num_cpus::get();</code></pre></div>
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<p>See <a href="https://docs.rs/rayon/1.*/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></details><h2 id="functions" class="section-header">Functions<a href="#functions" class="anchor">§</a></h2><ul class="item-table"><li><div class="item-name"><a class="fn" href="fn.get.html" title="fn num_cpus::get">get</a></div><div class="desc docblock-short">Returns the number of available CPUs of the current system.</div></li><li><div class="item-name"><a class="fn" href="fn.get_physical.html" title="fn num_cpus::get_physical">get_<wbr>physical</a></div><div class="desc docblock-short">Returns the number of physical cores of the current system.</div></li></ul></section></div></main></body></html> |