19 lines
4.8 KiB
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19 lines
4.8 KiB
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<!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="API documentation for the Rust `get` fn in crate `num_cpus`."><meta name="keywords" content="rust, rustlang, rust-lang, get"><title>num_cpus::get - Rust</title><link rel="stylesheet" type="text/css" href="../normalize.css"><link rel="stylesheet" type="text/css" href="../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../light.css" id="themeStyle"><link rel="stylesheet" type="text/css" href="../dark.css" disabled ><link rel="stylesheet" type="text/css" href="../ayu.css" disabled ><script id="default-settings"></script><script src="../storage.js"></script><noscript><link rel="stylesheet" href="../noscript.css"></noscript><link rel="icon" type="image/svg+xml" href="../favicon.svg">
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<link rel="alternate icon" type="image/png" href="../favicon-32x32.png"><style type="text/css">#crate-search{background-image:url("../down-arrow.svg");}</style></head><body class="rustdoc fn"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">☰</div><a href='../num_cpus/index.html'><div class='logo-container rust-logo'><img src='../rust-logo.png' alt='logo'></div></a><div class="sidebar-elems"><p class="location"><a href="index.html">num_cpus</a></p><script>window.sidebarCurrent = {name: "get", ty: "fn", relpath: ""};</script><script defer src="sidebar-items.js"></script></div></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!" aria-haspopup="menu"><img src="../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices" role="menu"></div></div><script src="../theme.js"></script><nav class="sub"><form class="search-form"><div class="search-container"><div><select id="crate-search"><option value="All crates">All crates</option></select><input class="search-input" name="search" disabled autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"></div><span class="help-button">?</span>
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<a id="settings-menu" href="../settings.html"><img src="../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><h1 class="fqn"><span class="out-of-band"><span id="render-detail"><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class="inner">−</span>]</a></span><a class="srclink" href="../src/num_cpus/lib.rs.html#72-74" title="goto source code">[src]</a></span><span class="in-band">Function <a href="index.html">num_cpus</a>::<wbr><a class="fn" href="">get</a></span></h1><pre class="rust fn">pub fn get() -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a></pre><div class="docblock"><p>Returns the number of available CPUs of the current system.</p>
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<p>This function will get the number of logical cores. Sometimes this is different from the number
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of physical cores (See <a href="https://en.wikipedia.org/wiki/Simultaneous_multithreading">Simultaneous multithreading on Wikipedia</a>).</p>
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<h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1>
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<div class="example-wrap"><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>();
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<span class="kw">if</span> <span class="ident">cpus</span> <span class="op">></span> <span class="number">1</span> {
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<span class="macro">println</span><span class="macro">!</span>(<span class="string">"We are on a multicore system with {} CPUs"</span>, <span class="ident">cpus</span>);
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} <span class="kw">else</span> {
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<span class="macro">println</span><span class="macro">!</span>(<span class="string">"We are on a single core system"</span>);
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}</pre></div>
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<h1 id="note" class="section-header"><a href="#note">Note</a></h1>
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<p>This will check <a href="http://www.gnu.org/software/libc/manual/html_node/CPU-Affinity.html">sched affinity</a> on Linux, showing a lower number of CPUs if the current
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thread does not have access to all the computer's CPUs.</p>
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<p>This will also check <a href="https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.txt">cgroups</a>, frequently used in containers to constrain CPU usage.</p>
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