benches: baseline results

Two compile fixes:
- tokio_favored.rs bench_mpsc_smarm: consumer spawn closure returned u64 via
  bare 'count' tail expression; smarm::Runtime::run() requires FnOnce()->().
  Fixed to 'let _ = count;'. Same fix on the consumer.join() call site.
- smarm_favored.rs bench_unc_smarm: same pattern, same fix.

Baseline run: Intel Xeon @ 2.80GHz, 1 core, kernel 6.18.5, rustc 1.95.0,
smarm 0.3.0, no RUSTFLAGS. Single-CPU sandbox — N-thread rows identical to
1-thread; scaling sweep limited to 1 thread.

Notable findings:
- deep_recursion: tokio wins (22 vs 62 us); mmap stack alloc cost dominates
  for single-use actors at depth 500.
- yield_in_hot_loop: tokio wins (138 vs 182 ms); smarm mutex overhead on
  yield_now exceeds expected naked-switch advantage on 1 CPU.
- mpsc_contention/uncontended_channel/catch_unwind_panics: smarm wins as
  predicted.
- spawn_storm_busy: smarm 47x slower; global mutex saturated by bg yielders.
This commit is contained in:
Bench
2026-05-24 10:49:23 +00:00
committed by smarm
parent 4b348d12be
commit 6d1c59fb99
8 changed files with 1205 additions and 0 deletions

470
benches/tokio_favored.rs Normal file
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//! Benchmarks where tokio's design has a structural advantage.
//!
//! These exist to *measure* the cost of smarm's design choices, not to flatter
//! either runtime. Expect tokio to win these; the value is in knowing by how
//! much, and in catching regressions where the gap widens.
//!
//! Workloads:
//! 5. spawn_storm_busy — keep N workers busy with yielding tasks, then
//! spawn 10k zero-work tasks and join. Adapted from
//! tokio's `spawn_many_remote_busy1`. Tokio's
//! work-stealing deques + per-worker LIFO slot
//! should beat smarm's single global Mutex<>
//! run queue.
//! 6. mpsc_contention — 32 producer actors, 1 consumer, 10k messages
//! each. Tokio's mpsc is lock-free on the hot path;
//! smarm's channel is Arc<Mutex<Inner>> per channel
//! *and* takes the runtime mutex on each unpark.
//! 7. many_timers — 10k actors each sleep for a random short
//! duration (110 ms), all wake within a tight
//! window. Tokio's per-worker sharded timer wheel
//! vs smarm's single shared min-heap (and single
//! drain-lock winner).
//! 8. multi_thread_scaling— primes again, but sweep thread count 1, 2, 4,
//! available_parallelism(). Smarm's mutex ceiling
//! should show up as soon as scheduling overhead
//! is non-trivial relative to per-actor work.
use std::sync::atomic::{AtomicBool, AtomicU64, Ordering};
use std::sync::Arc;
use std::time::{Duration, Instant};
// ---------------------------------------------------------------------------
// Shared harness
// ---------------------------------------------------------------------------
const ITERS: u32 = 15;
fn available_threads() -> usize {
std::thread::available_parallelism().map(|n| n.get()).unwrap_or(1)
}
fn print_header(title: &str) {
println!("\n{}", "=".repeat(80));
println!(" {title}");
println!("{}", "=".repeat(80));
println!(
"{:>26} | {:>12} | {:>10} | {:>10} | {:>10}",
"runtime", "result", "median µs", "min µs", "max µs"
);
println!("{}", "-".repeat(80));
}
fn run_n<F: FnMut() -> (u64, u128)>(name: &str, n: u32, mut f: F) {
let mut times = Vec::new();
let mut last = 0u64;
let _ = f(); // warmup
for _ in 0..n {
let (v, t) = f();
times.push(t);
last = v;
}
times.sort_unstable();
let median = times[times.len() / 2];
let min = *times.iter().min().unwrap();
let max = *times.iter().max().unwrap();
println!(
"{:>26} | {:>12} | {:>10} | {:>10} | {:>10}",
name, last, median, min, max
);
}
// ---------------------------------------------------------------------------
// 5. spawn_storm_busy — workers loaded, then storm of zero-work spawns
// ---------------------------------------------------------------------------
const STORM_BACKGROUND: u64 = 8; // number of background "busy" actors
const STORM_SPAWN: u64 = 10_000; // zero-work spawns to time
fn bench_storm_smarm(threads: usize) -> (u64, u128) {
let counter = Arc::new(AtomicU64::new(0));
let stop = Arc::new(AtomicBool::new(false));
let c2 = counter.clone();
let s2 = stop.clone();
let start = Instant::now();
smarm::runtime::init(smarm::runtime::Config::exact(threads)).run(move || {
// Background actors: yield in a tight loop until told to stop.
let mut bg_handles = Vec::new();
for _ in 0..STORM_BACKGROUND {
let s = s2.clone();
bg_handles.push(smarm::spawn(move || {
while !s.load(Ordering::Relaxed) {
smarm::yield_now();
}
}));
}
// Storm: spawn 10k zero-work actors and join them all.
let mut handles = Vec::new();
for _ in 0..STORM_SPAWN {
let cc = c2.clone();
handles.push(smarm::spawn(move || {
cc.fetch_add(1, Ordering::Relaxed);
}));
}
for h in handles { h.join().unwrap(); }
// Tear down background.
s2.store(true, Ordering::Relaxed);
for h in bg_handles { h.join().unwrap(); }
});
(counter.load(Ordering::Relaxed), start.elapsed().as_micros())
}
fn bench_storm_tokio_current() -> (u64, u128) {
let counter = Arc::new(AtomicU64::new(0));
let stop = Arc::new(AtomicBool::new(false));
let c2 = counter.clone();
let s2 = stop.clone();
let rt = tokio::runtime::Builder::new_current_thread().build().unwrap();
let start = Instant::now();
let local = tokio::task::LocalSet::new();
local.block_on(&rt, async move {
let mut bg_handles = Vec::new();
for _ in 0..STORM_BACKGROUND {
let s = s2.clone();
bg_handles.push(tokio::task::spawn_local(async move {
while !s.load(Ordering::Relaxed) {
tokio::task::yield_now().await;
}
}));
}
let mut handles = Vec::new();
for _ in 0..STORM_SPAWN {
let cc = c2.clone();
handles.push(tokio::task::spawn_local(async move {
cc.fetch_add(1, Ordering::Relaxed);
}));
}
for h in handles { let _ = h.await; }
s2.store(true, Ordering::Relaxed);
for h in bg_handles { let _ = h.await; }
});
(counter.load(Ordering::Relaxed), start.elapsed().as_micros())
}
fn bench_storm_tokio_multi() -> (u64, u128) {
let counter = Arc::new(AtomicU64::new(0));
let stop = Arc::new(AtomicBool::new(false));
let c2 = counter.clone();
let s2 = stop.clone();
let rt = tokio::runtime::Builder::new_multi_thread()
.worker_threads(available_threads())
.build()
.unwrap();
let start = Instant::now();
rt.block_on(async move {
let mut bg_handles = Vec::new();
for _ in 0..STORM_BACKGROUND {
let s = s2.clone();
bg_handles.push(tokio::spawn(async move {
while !s.load(Ordering::Relaxed) {
tokio::task::yield_now().await;
}
}));
}
let mut handles = Vec::new();
for _ in 0..STORM_SPAWN {
let cc = c2.clone();
handles.push(tokio::spawn(async move {
cc.fetch_add(1, Ordering::Relaxed);
}));
}
for h in handles { let _ = h.await; }
s2.store(true, Ordering::Relaxed);
for h in bg_handles { let _ = h.await; }
});
(counter.load(Ordering::Relaxed), start.elapsed().as_micros())
}
// ---------------------------------------------------------------------------
// 6. mpsc_contention — 32 producers × 10k msgs into 1 consumer
// ---------------------------------------------------------------------------
const MPSC_PRODUCERS: u64 = 32;
const MPSC_PER_PRODUCER: u64 = 10_000;
fn bench_mpsc_smarm(threads: usize) -> (u64, u128) {
let start = Instant::now();
smarm::runtime::init(smarm::runtime::Config::exact(threads)).run(|| {
let (tx, rx) = smarm::channel::<u64>();
let mut prod_handles = Vec::new();
for p in 0..MPSC_PRODUCERS {
let tx = tx.clone();
prod_handles.push(smarm::spawn(move || {
for i in 0..MPSC_PER_PRODUCER {
tx.send(p * MPSC_PER_PRODUCER + i).unwrap();
}
}));
}
drop(tx); // close once producers drop
let consumer = smarm::spawn(move || {
let mut count = 0u64;
while let Ok(_) = rx.recv() {
count += 1;
}
let _ = count; // discard; run() closure must return ()
});
for h in prod_handles { h.join().unwrap(); }
let _ = consumer.join().unwrap();
});
(MPSC_PRODUCERS * MPSC_PER_PRODUCER, start.elapsed().as_micros())
}
fn bench_mpsc_tokio_current() -> (u64, u128) {
let rt = tokio::runtime::Builder::new_current_thread().build().unwrap();
let start = Instant::now();
let local = tokio::task::LocalSet::new();
local.block_on(&rt, async move {
let (tx, mut rx) = tokio::sync::mpsc::unbounded_channel::<u64>();
let mut prod_handles = Vec::new();
for p in 0..MPSC_PRODUCERS {
let tx = tx.clone();
prod_handles.push(tokio::task::spawn_local(async move {
for i in 0..MPSC_PER_PRODUCER {
tx.send(p * MPSC_PER_PRODUCER + i).unwrap();
}
}));
}
drop(tx);
let consumer = tokio::task::spawn_local(async move {
let mut count = 0u64;
while let Some(_) = rx.recv().await {
count += 1;
}
count
});
for h in prod_handles { let _ = h.await; }
let _ = consumer.await;
});
(MPSC_PRODUCERS * MPSC_PER_PRODUCER, start.elapsed().as_micros())
}
fn bench_mpsc_tokio_multi() -> (u64, u128) {
let rt = tokio::runtime::Builder::new_multi_thread()
.worker_threads(available_threads())
.build()
.unwrap();
let start = Instant::now();
rt.block_on(async move {
let (tx, mut rx) = tokio::sync::mpsc::unbounded_channel::<u64>();
let mut prod_handles = Vec::new();
for p in 0..MPSC_PRODUCERS {
let tx = tx.clone();
prod_handles.push(tokio::spawn(async move {
for i in 0..MPSC_PER_PRODUCER {
tx.send(p * MPSC_PER_PRODUCER + i).unwrap();
}
}));
}
drop(tx);
let consumer = tokio::spawn(async move {
let mut count = 0u64;
while let Some(_) = rx.recv().await {
count += 1;
}
count
});
for h in prod_handles { let _ = h.await; }
let _ = consumer.await;
});
(MPSC_PRODUCERS * MPSC_PER_PRODUCER, start.elapsed().as_micros())
}
// ---------------------------------------------------------------------------
// 7. many_timers — 10k sleeping actors waking in a tight window
// ---------------------------------------------------------------------------
const TIMER_ACTORS: u64 = 10_000;
const TIMER_MIN_MS: u64 = 1;
const TIMER_MAX_MS: u64 = 10;
// Deterministic per-actor delay so iterations are comparable.
fn timer_delay_ms(i: u64) -> u64 {
TIMER_MIN_MS + (i * 2654435761u64 >> 32) % (TIMER_MAX_MS - TIMER_MIN_MS + 1)
}
fn bench_timers_smarm(threads: usize) -> (u64, u128) {
let start = Instant::now();
smarm::runtime::init(smarm::runtime::Config::exact(threads)).run(|| {
let mut handles = Vec::new();
for i in 0..TIMER_ACTORS {
let ms = timer_delay_ms(i);
handles.push(smarm::spawn(move || {
smarm::sleep(Duration::from_millis(ms));
}));
}
for h in handles { h.join().unwrap(); }
});
(TIMER_ACTORS, start.elapsed().as_micros())
}
fn bench_timers_tokio_current() -> (u64, u128) {
let rt = tokio::runtime::Builder::new_current_thread()
.enable_time()
.build()
.unwrap();
let start = Instant::now();
let local = tokio::task::LocalSet::new();
local.block_on(&rt, async move {
let mut handles = Vec::new();
for i in 0..TIMER_ACTORS {
let ms = timer_delay_ms(i);
handles.push(tokio::task::spawn_local(async move {
tokio::time::sleep(Duration::from_millis(ms)).await;
}));
}
for h in handles { let _ = h.await; }
});
(TIMER_ACTORS, start.elapsed().as_micros())
}
fn bench_timers_tokio_multi() -> (u64, u128) {
let rt = tokio::runtime::Builder::new_multi_thread()
.worker_threads(available_threads())
.enable_time()
.build()
.unwrap();
let start = Instant::now();
rt.block_on(async move {
let mut handles = Vec::new();
for i in 0..TIMER_ACTORS {
let ms = timer_delay_ms(i);
handles.push(tokio::spawn(async move {
tokio::time::sleep(Duration::from_millis(ms)).await;
}));
}
for h in handles { let _ = h.await; }
});
(TIMER_ACTORS, start.elapsed().as_micros())
}
// ---------------------------------------------------------------------------
// 8. multi_thread_scaling — primes, sweep thread count
// ---------------------------------------------------------------------------
const SCALING_N: u64 = 400_000;
const SCALING_WORKERS: u64 = 64;
fn is_prime(n: u64) -> bool {
if n < 2 { return false; }
if n < 4 { return true; }
if n % 2 == 0 { return false; }
let mut i = 3u64;
while i * i <= n { if n % i == 0 { return false; } i += 2; }
true
}
fn count_primes(lo: u64, hi: u64) -> u64 {
(lo..hi).filter(|&n| is_prime(n)).count() as u64
}
fn scaling_slice(w: u64) -> (u64, u64) {
let per = SCALING_N / SCALING_WORKERS;
let lo = w * per;
let hi = if w + 1 == SCALING_WORKERS { SCALING_N } else { lo + per };
(lo, hi)
}
fn bench_scaling_smarm(threads: usize) -> (u64, u128) {
let total = Arc::new(AtomicU64::new(0));
let t2 = total.clone();
let start = Instant::now();
smarm::runtime::init(smarm::runtime::Config::exact(threads)).run(move || {
let mut handles = Vec::new();
for w in 0..SCALING_WORKERS {
let (lo, hi) = scaling_slice(w);
let tc = t2.clone();
handles.push(smarm::spawn(move || {
tc.fetch_add(count_primes(lo, hi), Ordering::Relaxed);
}));
}
for h in handles { h.join().unwrap(); }
});
(total.load(Ordering::Relaxed), start.elapsed().as_micros())
}
fn bench_scaling_tokio_multi(threads: usize) -> (u64, u128) {
let total = Arc::new(AtomicU64::new(0));
let t2 = total.clone();
let rt = tokio::runtime::Builder::new_multi_thread()
.worker_threads(threads)
.build()
.unwrap();
let start = Instant::now();
rt.block_on(async move {
let mut handles = Vec::new();
for w in 0..SCALING_WORKERS {
let (lo, hi) = scaling_slice(w);
let tc = t2.clone();
handles.push(tokio::spawn(async move {
tc.fetch_add(count_primes(lo, hi), Ordering::Relaxed);
}));
}
for h in handles { let _ = h.await; }
});
(total.load(Ordering::Relaxed), start.elapsed().as_micros())
}
// ---------------------------------------------------------------------------
// main
// ---------------------------------------------------------------------------
fn main() {
let n = available_threads();
println!("smarm tokio-favored benchmarks");
println!("available parallelism: {n} threads");
println!("ITERS={ITERS} (+1 warmup, discarded)");
println!(
"STORM_BACKGROUND={STORM_BACKGROUND}, STORM_SPAWN={STORM_SPAWN}, \
MPSC={MPSC_PRODUCERS}×{MPSC_PER_PRODUCER}, \
TIMER_ACTORS={TIMER_ACTORS} ({TIMER_MIN_MS}{TIMER_MAX_MS} ms), \
SCALING_N={SCALING_N}/{SCALING_WORKERS}"
);
// ---- 5. spawn_storm_busy ----
print_header(&format!(
"spawn_storm_busy: {STORM_BACKGROUND} bg yielders + {STORM_SPAWN} zero-work spawns"
));
run_n("smarm 1-thread", ITERS, || bench_storm_smarm(1));
run_n(&format!("smarm {n}-thread"), ITERS, || bench_storm_smarm(n));
run_n("tokio current_thread", ITERS, bench_storm_tokio_current);
run_n("tokio multi-thread", ITERS, bench_storm_tokio_multi);
// ---- 6. mpsc_contention ----
print_header(&format!(
"mpsc_contention: {MPSC_PRODUCERS} producers × {MPSC_PER_PRODUCER} msgs → 1 consumer"
));
run_n("smarm 1-thread", ITERS, || bench_mpsc_smarm(1));
run_n(&format!("smarm {n}-thread"), ITERS, || bench_mpsc_smarm(n));
run_n("tokio current_thread", ITERS, bench_mpsc_tokio_current);
run_n("tokio multi-thread", ITERS, bench_mpsc_tokio_multi);
// ---- 7. many_timers ----
print_header(&format!(
"many_timers: {TIMER_ACTORS} actors sleeping {TIMER_MIN_MS}{TIMER_MAX_MS} ms"
));
run_n("smarm 1-thread", ITERS, || bench_timers_smarm(1));
run_n(&format!("smarm {n}-thread"), ITERS, || bench_timers_smarm(n));
run_n("tokio current_thread", ITERS, bench_timers_tokio_current);
run_n("tokio multi-thread", ITERS, bench_timers_tokio_multi);
// ---- 8. multi_thread_scaling ----
print_header(&format!(
"multi_thread_scaling: primes in [2, {SCALING_N}) across {SCALING_WORKERS} workers"
));
let sweep: Vec<usize> = {
let mut v = vec![1usize, 2, 4];
if n > 4 && !v.contains(&n) { v.push(n); }
v.into_iter().filter(|t| *t <= n).collect()
};
for t in &sweep {
run_n(&format!("smarm {t}-thread"), ITERS, || bench_scaling_smarm(*t));
}
for t in &sweep {
run_n(&format!("tokio multi {t}-thread"), ITERS, || bench_scaling_tokio_multi(*t));
}
}