5 releases (breaking)

Uses old Rust 2015

0.5.0 Apr 26, 2017
0.4.0 Nov 30, 2016
0.3.0 Feb 11, 2016
0.2.0 Dec 28, 2015
0.1.0 Nov 16, 2015

#11 in #locality

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Used in 15 crates (6 directly)

MIT license

1.5K SLoC


MIT licensed

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This project is a rust binding to the hwloc C library, which provides a portable abstraction of the hierarchical topology of modern architectures, including NUMA memory nodes, sockets, shared caches, cores and simultaneous multithreading.


Since this binding depends on the c library, you need to have it installed. The easiest way is to install it system-wide.

Here is a table of the version compatibility that we try to test for:

hwloc-rs libhwloc
0.5 1.11.5
0.4 1.11.5
0.3 1.11.2
0.2 1.11.1
0.1 1.11.1

Install hwloc on OS X

The easiest way is to download, build and install the sources from the website.

  1. Download the artifact.
  2. tar -xvzpf hwloc-1.11.5.tar.gz
  3. cd hwloc-1.11.5
  4. ./configure && make && sudo make install

You can check if it works by trying the lstopo command. Here is the sample output for a Mid 2012 MacBook Pro with 16GB of RAM:

~ $ lstopo
Machine (16GB total) + NUMANode L#0 (P#0 16GB) + L3 L#0 (6144KB)
  L2 L#0 (256KB) + L1d L#0 (32KB) + L1i L#0 (32KB) + Core L#0
    PU L#0 (P#0)
    PU L#1 (P#1)
  L2 L#1 (256KB) + L1d L#1 (32KB) + L1i L#1 (32KB) + Core L#1
    PU L#2 (P#2)
    PU L#3 (P#3)
  L2 L#2 (256KB) + L1d L#2 (32KB) + L1i L#2 (32KB) + Core L#2
    PU L#4 (P#4)
    PU L#5 (P#5)
  L2 L#3 (256KB) + L1d L#3 (32KB) + L1i L#3 (32KB) + Core L#3
    PU L#6 (P#6)
    PU L#7 (P#7)

Install hwloc on Linux (Ubuntu 14.04)

On Ubuntu 14.04 installing it through apt is probably the easiest.

~ $ sudo apt-get install hwloc libhwloc-dev

You can again check with lstopo. The following is a 2-core virtual machine:

ubuntu-trusty-64:~$ lstopo
Machine (490MB)
  Socket L#0 + L2d L#0 (6144KB)
    L1d L#0 (32KB) + Core L#0 + PU L#0 (P#0)
    L1d L#1 (32KB) + Core L#1 + PU L#1 (P#1)
  HostBridge L#0
    PCI 80ee:beef
    PCI 8086:100e
      Net L#0 "eth0"
    PCI 8086:100e
      Net L#1 "eth1"
    PCI 8086:2829
      Block L#2 "sda"

Install hwloc on Windows (Windows 10)

  1. Download and extract the 64bit binaries.
  2. Add the /bin folder to your PATH environment variable.
  3. Add the /lib folder to your LIB environment variable.

After restarting your shell you should be able to start lstopo.


First, add the following to your Cargo.toml:

hwloc = "0.5.0"

Next, add this to your crate root:

extern crate hwloc;

Here is a quick example which walks the Topology and prints it out:

extern crate hwloc;

use hwloc::Topology;

fn main() {
	let topo = Topology::new();

	for i in 0..topo.depth() {
		println!("*** Objects at level {}", i);

		for (idx, object) in topo.objects_at_depth(i).iter().enumerate() {
			println!("{}: {}", idx, object);

You can also look at more examples, if you want to run them check out the next section below.

Running Examples

The library ships with examples, and to run them you need to clone the repository and then run them through cargo run --example=.

$ git clone https://github.com/daschl/hwloc-rs.git
$ cd hwloc-rs

To run an example (which will download the dependencies and build it) you can use cargo run -example=:

$ cargo run --example=walk_tree
   Compiling libc v0.2.3
   Compiling hwloc v0.2.0 (file:///vagrant/hwloc-rs)
     Running `target/debug/examples/walk_tree`
*** Printing overall tree
Machine (490MB): #0
 Socket (): #0
  L2d (6144KB): #4294967295
   L1d (32KB): #4294967295
    Core (): #0
     PU (): #0
   L1d (32KB): #4294967295
    Core (): #1
     PU (): #1


This project uses the MIT license, please see the LICENSE file for more information.