scx_rustlite: simple vtime-based scheduler written in Rust

Provide a simple scheduler with a BPF part and a user-space counterpart,
written in Rust, that can be used as a template to implement more
complex scheduling policies.

The main goal of this scheduler is to be easy to read and well
documented, so that newcomers (i.e., students, researchers, junior devs,
etc.) can use it to quickly experiment their scheduling theories.

For this reason the design of this scheduler is mostly focused on
simplicity and code readability.

Signed-off-by: Andrea Righi <[email protected]>

scheds/rust/meson.build

@@ -1,2 +1,3 @@
 subdir('scx_layered')
 subdir('scx_rusty')
+subdir('scx_rustlite')

scheds/rust/scx_rustlite/.gitignore

@@ -0,0 +1,3 @@
+src/bpf/.output
+Cargo.lock
+target

scheds/rust/scx_rustlite/Cargo.toml

@@ -0,0 +1,27 @@
+[package]
+name = "scx_rustlite"
+version = "0.0.1"
+authors = ["Andrea Righi <[email protected]>", "Canonical"]
+edition = "2021"
+description = "Userspace scheduling with BPF"
+license = "GPL-2.0-only"
+
+[dependencies]
+anyhow = "1.0.65"
+bitvec = { version = "1.0", features = ["serde"] }
+clap = { version = "4.1", features = ["derive", "env", "unicode", "wrap_help"] }
+ctrlc = { version = "3.1", features = ["termination"] }
+fb_procfs = "0.7.0"
+hex = "0.4.3"
+libbpf-rs = "0.22.0"
+libc = "0.2.137"
+log = "0.4.17"
+ordered-float = "3.4.0"
+scx_utils = { path = "../../../rust/scx_utils", version = "0.4" }
+simplelog = "0.12.0"
+
+[build-dependencies]
+scx_utils = { path = "../../../rust/scx_utils", version = "0.4" }
+
+[features]
+enable_backtrace = []

scheds/rust/scx_rustlite/LICENSE

@@ -0,0 +1 @@
+../../../LICENSE

scheds/rust/scx_rustlite/build.rs

@@ -0,0 +1,11 @@
+// This software may be used and distributed according to the terms of the
+// GNU General Public License version 2.
+
+fn main() {
+    scx_utils::BpfBuilder::new()
+        .unwrap()
+        .enable_intf("src/bpf/intf.h", "bpf_intf.rs")
+        .enable_skel("src/bpf/main.bpf.c", "bpf")
+        .build()
+        .unwrap();
+}

scheds/rust/scx_rustlite/meson.build

@@ -0,0 +1,7 @@
+custom_target('scx_rustlite',
+              output: '@PLAINNAME@.__PHONY__',
+              input: 'Cargo.toml',
+              command: [cargo, 'build', '--manifest-path=@INPUT@', '--target-dir=@OUTDIR@',
+                        cargo_build_args],
+              env: cargo_env,
+              build_by_default: true)

scheds/rust/scx_rustlite/rustfmt.toml

@@ -0,0 +1,8 @@
+# Get help on options with `rustfmt --help=config`
+# Please keep these in alphabetical order.
+edition = "2021"
+group_imports = "StdExternalCrate"
+imports_granularity = "Item"
+merge_derives = false
+use_field_init_shorthand = true
+version = "Two"

scheds/rust/scx_rustlite/src/bpf/intf.h

@@ -0,0 +1,33 @@
+// This software may be used and distributed according to the terms of the
+// GNU General Public License version 2.
+
+#ifndef __INTF_H
+#define __INTF_H
+
+#define MAX(x, y) ((x) > (y) ? (x) : (y))
+#define MIN(x, y) ((x) < (y) ? (x) : (y))
+
+#include <stdbool.h>
+#ifndef __kptr
+#ifdef __KERNEL__
+#error "__kptr_ref not defined in the kernel"
+#endif
+#define __kptr
+#endif
+
+#ifndef __KERNEL__
+typedef unsigned char u8;
+typedef unsigned int u32;
+typedef int s32;
+typedef unsigned long long u64;
+typedef long long s64;
+#endif
+
+#include <scx/ravg.bpf.h>
+
+struct task_ctx {
+	s32 pid;
+	u64 vtime;
+};
+
+#endif /* __INTF_H */