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topology: Add new topology crate

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The topology.rs crate is insufficiently generic, and reflects
implementation details of scx_rusty more than it provides generic use
cases for modeling a host's topology. This adds a new topology2.rs crate
that will replace topology.rs. We have this as an intermediate commit so
that we don't bundle updating scx_rusty with adding this crate.

Signed-off-by: David Vernet <void@manifault.com>
This commit is contained in:
David Vernet 2024-02-22 20:06:16 -06:00
parent 608df7f96f
commit c5a3b83bbd
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7
rust/scx_utils/src/lib.rs
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@ -48,5 +48,12 @@ mod topology;
pub use topology::Domain;
pub use topology::Topology;
mod topology2;
pub use topology2::Topology2;
pub use topology2::Cpu;
pub use topology2::Core;
pub use topology2::Cache;
pub use topology2::Node;
mod cpumask;
pub use cpumask::Cpumask;

349
rust/scx_utils/src/topology2.rs Normal file
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@ -0,0 +1,349 @@
// Copyright (c) Meta Platforms, Inc. and affiliates.
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2.
//! # SCX Topology
//!
//! A crate that allows schedulers to inspect and model the host's topology, in
//! service of creating scheduling domains.
//!
//! A Topology is comprised of one or more Node objects, which themselves are
//! comprised hierarchically of Cache -> Core -> Cpu objects respectively:
//!
//! Topology
//! |
//! o---------------------o---------------------o
//! | | |
//! | | |
//! o---------------o----------------o ... o----------------o---------------o
//! | Node | | Node |
//! | ID 0 | | ID 1 |
//! | Caches <id, Cache> | | Caches <id, Cache> |
//! | Span 0x00000fffff00000fffff | | Span 0xfffff00000fffff00000 |
//! o--------------------------------o o--------------------------------o
//! |
//! |
//! o--------------------------------o ... o--------------------------------o
//! | Cache | | Cache |
//! | ID 0 | | ID 1 |
//! | Cores <id, Core> | | Cores <id, Core> |
//! | Span 0x00000ffc0000000ffc00 | | Span 0x00000003ff00000003ff |
//! o--------------------------------o o----------------o---------------o
//! |
//! |
//! o--------------------------------o ... o--------------------------------o
//! | Core | | Core |
//! | ID 0 | | ID 9 |
//! | Cpus <id, Cpu> | | Cpus <id, Cpu> |
//! | Span 0x00000000010000000001 | | Span 0x00000002000000000200 |
//! o--------------------------------o o----------------o---------------o
//! |
//! |
//! o--------------------------------o ... o---------------------------------o
//! | Cpu | | Cpu |
//! | ID 9 | | ID 49 |
//! | online 1 | | online 1 |
//! | min_freq 400000 | | min_freq 400000 |
//! | max_freq 5881000 | | min_freq 5881000 |
//! o--------------------------------o o---------------------------------o
//!
//! Every object contains a Cpumask that spans all CPUs in that point in the
//! topological hierarchy.
//!
//! Creating Topology
//! -----------------
//!
//! Topology objects are created using the static new function:
//!
//!```
//! let top = Topology::new()?;
//!```
//!
//! Querying Topology
//! -----------------
//!
//! With a created Topology, you can query the topological hierarchy using the
//! set of accessor functions defined below. All objects in the topological
//! hierarchy are (currently) entirely read-only, though that may change if and
//! when we add support for dynamically updating the hierarchy during e.g. CPU
//! hotplug.
use crate::Cpumask;
use anyhow::bail;
use anyhow::Result;
use glob::glob;
use sscanf::sscanf;
use std::collections::BTreeMap;
use std::path::Path;
#[derive(Debug, Clone)]
pub struct Cpu {
id: usize,
online: bool,
min_freq: usize,
max_freq: usize,
}
impl Cpu {
/// Get the ID of this Cpu
pub fn id(&self) -> usize {
self.id
}
/// Is this CPU online?
pub fn cpus(&self) -> bool {
self.online
}
/// Get the minimum scaling frequency of this CPU
pub fn min_freq(&self) -> usize {
self.min_freq
}
/// Get the maximum scaling frequency of this CPU
pub fn max_freq(&self) -> usize {
self.max_freq
}
}
#[derive(Debug, Clone)]
pub struct Core {
id: usize,
cpus: BTreeMap<usize, Cpu>,
span: Cpumask,
}
impl Core {
/// Get the ID of this Core
pub fn id(&self) -> usize {
self.id
}
/// Get the map of CPUs inside this Core
pub fn cpus(&self) -> &BTreeMap<usize, Cpu> {
&self.cpus
}
/// Get a Cpumask of all SMT siblings in this Core
pub fn span(&self) -> Cpumask {
self.span.clone()
}
}
#[derive(Debug, Clone)]
pub struct Cache {
id: usize,
cores: BTreeMap<usize, Core>,
span: Cpumask,
}
impl Cache {
/// Get the ID of this LLC
pub fn id(&self) -> usize {
self.id
}
/// Get the map of cores inside this LLC
pub fn cores(&self) -> &BTreeMap<usize, Core> {
&self.cores
}
/// Get a Cpumask of all CPUs in this LLC
pub fn span(&self) -> Cpumask {
self.span.clone()
}
}
#[derive(Debug, Clone)]
pub struct Node {
id: usize,
llcs: BTreeMap<usize, Cache>,
span: Cpumask,
}
impl Node {
/// Get the ID of this NUMA node
pub fn id(&self) -> usize {
self.id
}
/// Get the map of LLCs inside this NUMA node
pub fn llcs(&self) -> &BTreeMap<usize, Cache> {
&self.llcs
}
/// Get a Cpumask of all CPUs in this NUMA node
pub fn span(&self) -> Cpumask {
self.span.clone()
}
}
#[derive(Debug)]
pub struct Topology2 {
nodes: Vec<Node>,
nr_cpus: usize,
span: Cpumask,
}
impl Topology2 {
/// Build a complete host Topology
pub fn new() -> Result<Topology2> {
let nr_cpus = libbpf_rs::num_possible_cpus()?;
let span = cpus_online()?;
let nodes = create_numa_nodes(&span)?;
Ok(Topology2 { nodes, nr_cpus, span })
}
/// Get a slice of the NUMA nodes on the host
pub fn nodes(&self) -> &[Node] {
&self.nodes
}
/// Get the number of total CPUs on the host
pub fn nr_cpus(&self) -> usize {
self.nr_cpus
}
/// Get a cpumask of all the online CPUs on the host
pub fn span(&self) -> Cpumask {
self.span.clone()
}
}
/**********************************************
* Helper functions for creating the Topology *
**********************************************/
const CACHE_LEVEL: usize = 3;
fn read_file_usize(path: &Path) -> Result<usize> {
let val = match std::fs::read_to_string(&path) {
Ok(val) => val,
Err(_) => {
bail!("Failed to open or read file {:?}", path);
}
};
match val.trim().parse::<usize>() {
Ok(parsed) => Ok(parsed),
Err(_) => {
bail!("Failed to parse {}", val);
}
}
}
fn cpus_online() -> Result<Cpumask> {
let path = "/sys/devices/system/cpu/online";
let online = std::fs::read_to_string(&path)?;
let online_groups: Vec<&str> = online.split(',').collect();
let mut mask = Cpumask::new()?;
for group in online_groups.iter() {
let (min, max) = match sscanf!(group.trim(), "{usize}-{usize}") {
Ok((x, y)) => (x, y),
Err(_) => {
bail!("Failed to parse online cpus {}", group.trim());
}
};
for i in min..max {
mask.set_cpu(i)?;
}
}
Ok(mask)
}
fn create_numa_nodes(online_mask: &Cpumask) -> Result<Vec<Node>> {
let mut nodes: Vec<Node> = Vec::new();
let numa_paths = glob("/sys/devices/system/node/node*")?;
for numa_path in numa_paths.filter_map(Result::ok) {
let numa_str = numa_path.to_str().unwrap().trim();
let node_id = match sscanf!(numa_str, "/sys/devices/system/node/node{usize}") {
Ok(val) => val,
Err(_) => {
bail!("Failed to parse NUMA node ID {}", numa_str);
}
};
let mut node = Node {
id: node_id,
llcs: BTreeMap::new(),
span: Cpumask::new()?,
};
let cpu_pattern = numa_path.join("cpu[0-9]*");
let cpu_paths = glob(cpu_pattern.to_string_lossy().as_ref())?;
for cpu_path in cpu_paths.filter_map(Result::ok) {
let cpu_str = cpu_path.to_str().unwrap().trim();
let cpu_id = match sscanf!(cpu_str, "/sys/devices/system/node/node{usize}/cpu{usize}") {
Ok((_, val)) => val,
Err(_) => {
bail!("Failed to parse cpu ID {}", cpu_str);
}
};
// Physical core ID
let top_path = cpu_path.join("topology");
let core_id = read_file_usize(&top_path.join("core_id"))?;
// L3 cache ID
let cache_path = cpu_path.join("cache");
let llc_id =
read_file_usize(&cache_path.join(format!("index{}", CACHE_LEVEL)).join("id"))?;
// Min and max frequencies. If the kernel is not compiled with
// CONFIG_CPU_FREQ, just assume 0 for both frequencies.
let freq_path = cpu_path.join("cpufreq");
let min_freq = read_file_usize(&freq_path.join("scaling_min_freq")).unwrap_or(0);
let max_freq = read_file_usize(&freq_path.join("scaling_max_freq")).unwrap_or(0);
// Hotplug information
let online = online_mask.test_cpu(cpu_id);
if !node.llcs.contains_key(&llc_id) {
let cache = Cache {
id: llc_id,
cores: BTreeMap::new(),
span: Cpumask::new()?,
};
node.llcs.insert(llc_id, cache);
}
let cache = node.llcs.get_mut(&llc_id).unwrap();
if !cache.cores.contains_key(&core_id) {
let core = Core {
id: core_id,
cpus: BTreeMap::new(),
span: Cpumask::new()?,
};
cache.cores.insert(core_id, core);
}
let core = cache.cores.get_mut(&core_id).unwrap();
core.cpus.insert(
cpu_id,
Cpu {
id: cpu_id,
online: online,
min_freq: min_freq,
max_freq: max_freq,
},
);
if node.span.test_cpu(cpu_id) {
bail!("Node {} already had CPU {}", node_id, cpu_id);
}
// Update all of the devices' spans to include this CPU.
core.span.set_cpu(cpu_id)?;
cache.span.set_cpu(cpu_id)?;
node.span.set_cpu(cpu_id)?;
}
nodes.push(node);
}
Ok(nodes)
}