[Features][CustomSched][BPFLib]

    * Custom Scheduling
    * Capturing cgroup stats on per invoke level
    * BPFLibrary to create a pinned BPFMap of function characteristics
      * used to share data with scx scheduler

.gitignore

@@ -4,4 +4,5 @@ __pycache__/*.lock
 **.lock
 **__pycache__**
 .idea/
-.vscode/
+.vscode/
+**.swp

pr.md

@@ -0,0 +1,15 @@
+
+
+
+```
+Error when --all-features is used for check command. 
+
+  Compiling libbpf-sys v1.5.0+v1.5.0
+  error: could not find native static library `elf`, perhaps an -L flag is missing?
+
+  error: could not compile `libbpf-sys` (lib) due to 1 previous error
+  make: *** [Makefile:26: check] Error 101
+```
+
+
+

src/Ilúvatar/.gitignore

@@ -4,5 +4,5 @@ iluvatar_worker/src/worker.dev*json
 iluvatar_worker_library/tests/resources/worker.dev*json
 iluvatar_controller/src/controller.dev*json
 target/
-**.swp
-.vscode/
+**.sw*
+.vscode/

src/Ilúvatar/Cargo.toml

@@ -8,7 +8,9 @@ members = [
   "iluvatar_library",
   "iluvatar_worker_library",
   "iluvatar_energy_mon",
-  "iluvatar_rpc"
+  "iluvatar_rpc",
+  "iluvatar_bpf_library",
+  "fs_policy_tsksz",
 ]
 resolver = "2"
 

src/Ilúvatar/Cross.toml

@@ -5,5 +5,9 @@ passthrough = ["ARCH=amd64", "GO_VERSION=1.22.0", "CNI_VERSION=v1.1.1", "GOPATH=
 default-target = "x86_64-unknown-linux-gnu"    # use this target if none is explicitly provided
 pre-build = [                                  # additional commands to run prior to building the package
     "dpkg --add-architecture $CROSS_DEB_ARCH", 
-    "apt-get update && apt-get --assume-yes install protobuf-compiler iproute2 wget curl runc bridge-utils iptables net-tools sysstat"
+    "apt-get update && apt-get --assume-yes install protobuf-compiler iproute2 wget curl runc bridge-utils iptables net-tools sysstat libelf-dev lsb-release wget software-properties-common gnupg",
+    "wget https://apt.llvm.org/llvm.sh && chmod +x llvm.sh &&  ./llvm.sh  all &&  ln -s /usr/bin/ld.lld-18 /usr/bin/ld.lld &&  ln -s /usr/bin/clang-18 /usr/bin/clang &&  ln -s /usr/bin/clang++-18 /usr/bin/clang++ && rm llvm.sh"
 ]
+
+
+

src/Ilúvatar/Makefile

@@ -12,7 +12,7 @@ endif
 RUST_C?=cross
 DEBUG_FLAGS=--all-targets $(TARGET) -j $(NPROCS)
 RELEASE_FLAGS=--lib --bins $(TARGET) -j $(NPROCS) --release
-CARGO_ARGS?=""
+CARGO_ARGS?=
 
 default: debug
 
@@ -23,7 +23,7 @@ clean:
 	@$(RUST_C) clean
 check:
 	@echo "Checking"
-	@RUSTFLAGS=$(RUST_FLAGS) $(RUST_C) check --all-features $(DEBUG_FLAGS) $(CARGO_ARGS)
+	@RUSTFLAGS=$(RUST_FLAGS) $(RUST_C) check $(DEBUG_FLAGS) $(CARGO_ARGS)
 release:
 	@echo "Building release"
 	@RUSTFLAGS=$(RUST_FLAGS) $(RUST_C) build $(RELEASE_FLAGS) $(CARGO_ARGS)
@@ -37,6 +37,10 @@ tiny:
 debug:
 	@echo "Building debug"
 	@RUSTFLAGS=$(RUST_FLAGS) $(RUST_C) build $(DEBUG_FLAGS) $(CARGO_ARGS)
+fix:
+	@echo "Fixing lint errors"
+	@RUSTFLAGS=$(RUST_FLAGS) $(RUST_C) fix $(DEBUG_FLAGS) $(CARGO_ARGS)
+	@RUSTFLAGS=$(RUST_FLAGS) $(RUST_C) clippy --fix --allow-no-vcs --workspace --examples --benches --no-deps -- -Dclippy::suspicious -Dclippy::correctness -Dclippy::perf -Aclippy::single_match -Aclippy::new_without_default -Aclippy::too_many_arguments -Aclippy::type-complexity -Dclippy::from_over_into -Aclippy::redundant-field-names -Dwarnings
 spans:
 	@echo "Building full_spans"
 	@RUSTFLAGS=$(RUST_FLAGS) $(RUST_C) build --features full_spans $(RELEASE_FLAGS) $(CARGO_ARGS)

src/Ilúvatar/ansible/worker.yml

@@ -123,6 +123,14 @@
       remote_src: "{{__remote_bin_src}}"
     become: yes
 
+  - name: copy fs_policy_tsksz 
+    ansible.builtin.copy:
+      src: "{{__bin_src}}/fs_policy_tsksz"
+      dest: "{{bin_dir}}/"
+      mode: "preserve"
+      remote_src: "{{__remote_bin_src}}"
+    become: yes
+
   - name: copy worker config
     ansible.builtin.copy:
       src: "{{__bin_src}}/{{worker.config_name}}"

src/Ilúvatar/fs_policy_tsksz/Cargo.toml

@@ -0,0 +1,33 @@
+[package]
+name = "fs_policy_tsksz"
+version = "0.0.3"
+authors = ["Abdul Rehman <[email protected]>"]
+edition = "2021"
+description = "A simple scheduler that preserves locality for a function cgroup"
+license = "GPL-2.0-only"
+
+[dependencies]
+anyhow = "1.0.65"
+plain = "0.2.3"
+ctrlc = { version = "3.1", features = ["termination"] }
+libbpf-rs = "0.24.1"
+libc = "0.2.137"
+scx_utils = { version = "1.0.6" }
+scx_rustland_core = { version = "2.2.3" }
+
+# Specific to iluvatar 
+iluvatar_library = { path = "../iluvatar_library" }
+iluvatar_worker_library = { path = "../iluvatar_worker_library" }
+clap = { version = "4.5.4", features = ["derive"] }
+ipc-channel = { version = "0.18.1", features = ["memfd"] }
+serde = { version = "1.0" }
+
+[build-dependencies]
+scx_utils = { version = "1.0.6" }
+scx_rustland_core = { version = "2.2.3" }
+
+[features]
+enable_backtrace = []
+
+
+

src/Ilúvatar/fs_policy_tsksz/LICENSE

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

src/Ilúvatar/fs_policy_tsksz/README.md

@@ -0,0 +1,20 @@
+# scx_rlfifo
+
+This is a single user-defined scheduler used within [sched_ext](https://github.com/sched-ext/scx/tree/main), which is a Linux kernel feature which enables implementing kernel thread schedulers in BPF and dynamically loading them. [Read more about sched_ext](https://github.com/sched-ext/scx/tree/main).
+
+## Overview
+
+scx_rlfifo is a simple FIFO scheduler runs in user-space, based on the
+scx_rustland_core framework.
+
+## Typical Use Case
+
+This scheduler is provided as a simple template that can be used as a baseline
+to test more complex scheduling policies.
+
+## Production Ready?
+
+Definitely not. Using this scheduler in a production environment is not
+recommended, unless there are specific requirements that necessitate a basic
+FIFO scheduling approach. Even then, it's still recommended to use the kernel's
+SCHED_FIFO real-time class.

src/Ilúvatar/fs_policy_tsksz/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();
+}

src/Ilúvatar/fs_policy_tsksz/meson.build

@@ -0,0 +1,14 @@
+if serialize
+  sched_deps = [libbpf, bpftool_target, sched]
+else
+  sched_deps = [libbpf, bpftool_target]
+endif
+
+sched = custom_target('scx_rlfifo',
+              output: '@PLAINNAME@.__PHONY__',
+              input: 'Cargo.toml',
+              command: [cargo, 'build', '--manifest-path=@INPUT@', '--target-dir=@OUTDIR@',
+                        cargo_build_args],
+              env: cargo_env,
+              depends: sched_deps,
+              build_always_stale: true)

src/Ilúvatar/fs_policy_tsksz/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"

src/Ilúvatar/fs_policy_tsksz/src/bpf.rs

@@ -0,0 +1,187 @@
+// Copyright (c) Andrea Righi <[email protected]>
+
+// This software may be used and distributed according to the terms of the
+// GNU General Public License version 2.
+
+use std::mem::MaybeUninit;
+
+use crate::bpf_intf;
+use crate::bpf_skel::*;
+
+use anyhow::Context;
+use anyhow::Result;
+
+use libbpf_rs::skel::OpenSkel;
+use libbpf_rs::skel::Skel;
+use libbpf_rs::skel::SkelBuilder;
+use libbpf_rs::OpenObject;
+
+use libc::{pthread_self, pthread_setschedparam, sched_param};
+
+#[cfg(target_env = "musl")]
+use libc::timespec;
+
+use scx_utils::scx_ops_attach;
+use scx_utils::scx_ops_load;
+use scx_utils::scx_ops_open;
+use scx_utils::uei_exited;
+use scx_utils::uei_report;
+use scx_utils::UserExitInfo;
+
+use scx_rustland_core::ALLOCATOR;
+
+// Defined in UAPI
+const SCHED_EXT: i32 = 7;
+
+pub struct BpfScheduler<'cb> {
+    pub skel: BpfSkel<'cb>,                   // Low-level BPF connector
+    struct_ops: Option<libbpf_rs::Link>,      // Low-level BPF methods
+    queued_stats: libbpf_rs::RingBuffer<'cb>, // ring buffer of tasks pids to be switched to schedext
+}
+
+#[derive(Clone, Copy, Debug)]
+#[allow(non_camel_case_types, dead_code)]
+pub struct lpolicy_stats(bpf_intf::policy_stats);
+
+macro_rules! define_buffer {
+    ( $bufname: ident, $abufname: ident, $abuf: ident, $callback: ident, $tdst: ty ) => {
+        const $bufname: usize = std::mem::size_of::<$tdst>();
+        #[repr(align(8))]
+        struct $abufname([u8; $bufname]);
+        static mut $abuf: $abufname = $abufname([0; $bufname]);
+        fn $callback(data: &[u8]) -> i32 {
+            unsafe {
+                $abuf.0.copy_from_slice(data);
+            }
+            LIBBPF_STOP
+        }
+    };
+}
+
+define_buffer!(
+    BUFSIZE_STATS,
+    AlignedBufferstats,
+    BUF_STATS,
+    callback_stats,
+    bpf_intf::policy_stats
+);
+fn fetch_stats(bytes: &[u8]) -> lpolicy_stats {
+    let ps = unsafe { *(bytes.as_ptr() as *const bpf_intf::policy_stats) };
+    lpolicy_stats(ps)
+}
+
+// Special negative error code for libbpf to stop after consuming just one item from a BPF
+// ring buffer.
+const LIBBPF_STOP: i32 = -255;
+
+impl<'cb> BpfScheduler<'cb> {
+    pub fn init(
+        open_object: &'cb mut MaybeUninit<OpenObject>,
+        slice_us: u64,
+        exit_dump_len: u32,
+        verbose: bool,
+    ) -> Result<Self> {
+        // Open the BPF prog first for verification.
+        let mut skel_builder = BpfSkelBuilder::default();
+        skel_builder.obj_builder.debug(verbose);
+        let mut skel = scx_ops_open!(skel_builder, open_object, tsksz_ops)?;
+
+        // Lock all the memory to prevent page faults that could trigger potential deadlocks during
+        // scheduling.
+        ALLOCATOR.lock_memory();
+
+        skel.struct_ops.tsksz_ops_mut().exit_dump_len = exit_dump_len;
+        skel.maps.bss_data.usersched_pid = std::process::id();
+        skel.maps.rodata_data.effective_slice_ns = slice_us * 1000;
+
+        let path = "/sys/fs/bpf/func_metadata";
+        let func_metadata = &mut skel.maps.func_metadata;
+        assert!(func_metadata.reuse_pinned_map("/asdf").is_err());
+        func_metadata
+            .reuse_pinned_map(path)
+            .expect("failed to reuse map");
+
+        // Attach BPF scheduler.
+        let mut skel = scx_ops_load!(skel, tsksz_ops, uei)?;
+        let struct_ops = Some(scx_ops_attach!(skel, tsksz_ops)?);
+
+        // Build the ring buffer of queued tasks.
+        let rb_map = &mut skel.maps.queued_stats;
+        let mut builder = libbpf_rs::RingBufferBuilder::new();
+        builder.add(rb_map, callback_stats).unwrap();
+        let queued_stats = builder.build().unwrap();
+
+        // Make sure to use the SCHED_EXT class at least for the scheduler itself.
+        match Self::use_sched_ext() {
+            0 => Ok(Self {
+                skel,
+                struct_ops,
+                queued_stats,
+            }),
+            err => Err(anyhow::Error::msg(format!(
+                "sched_setscheduler error: {}",
+                err
+            ))),
+        }
+    }
+
+    // Receive stats from the BPF scheduler to switch to schedext policy.
+    pub fn dequeue_stats(&mut self) -> Result<Option<lpolicy_stats>, i32> {
+        match self.queued_stats.consume_raw() {
+            0 => Ok(None),
+            LIBBPF_STOP => {
+                // A valid pid is received, convert data to a proper pid.
+                let stats = unsafe { fetch_stats(&BUF_STATS.0) };
+                Ok(Some(stats))
+            }
+            res if res < 0 => Err(res),
+            res => panic!(
+                "Unexpected return value from libbpf-rs::consume_raw(): {}",
+                res
+            ),
+        }
+    }
+
+    // Set scheduling class for the scheduler itself to SCHED_EXT
+    fn use_sched_ext() -> i32 {
+        #[cfg(target_env = "gnu")]
+        let param: sched_param = sched_param { sched_priority: 0 };
+        #[cfg(target_env = "musl")]
+        let param: sched_param = sched_param {
+            sched_priority: 0,
+            sched_ss_low_priority: 0,
+            sched_ss_repl_period: timespec {
+                tv_sec: 0,
+                tv_nsec: 0,
+            },
+            sched_ss_init_budget: timespec {
+                tv_sec: 0,
+                tv_nsec: 0,
+            },
+            sched_ss_max_repl: 0,
+        };
+
+        unsafe { pthread_setschedparam(pthread_self(), SCHED_EXT, &param as *const sched_param) }
+    }
+
+    // Read exit code from the BPF part.
+    pub fn exited(&mut self) -> bool {
+        uei_exited!(&self.skel, uei)
+    }
+
+    // Called on exit to shutdown and report exit message from the BPF part.
+    pub fn shutdown_and_report(&mut self) -> Result<UserExitInfo> {
+        self.struct_ops.take();
+        uei_report!(&self.skel, uei)
+    }
+}
+
+// Disconnect the low-level BPF scheduler.
+impl<'a> Drop for BpfScheduler<'a> {
+    fn drop(&mut self) {
+        if let Some(struct_ops) = self.struct_ops.take() {
+            drop(struct_ops);
+        }
+        ALLOCATOR.unlock_memory();
+    }
+}