perf: reduce packet buffer slicing churn (#2381)

* bench: add packet bytes extraction Criterion benchmark Adds a Criterion benchmark under easytier/benches/ covering ZCPacket::payload_bytes and tunnel_payload_bytes at 1280/4096-byte payload sizes, using iter_batched so ZCPacket construction stays in the setup phase and is excluded from the timed region. - Register the [[bench]] entry in easytier/Cargo.toml. - Document the bench and PACKET_BYTES_* env vars in benches/README.md. * perf: reduce packet buffer slicing churn Replace BytesMut::split_off with Buf::advance in ZCPacket bytes extraction paths (payload_bytes, tunnel_payload_bytes, convert_type, drop_foreign_header) and in TunZCPacketToBytes, and simplify the copy_from_slice in new_from_payload. When the buffer is in its unique (VEC) representation, split_off promotes it to the shared (ARC) representation, allocating a Shared control block and bumping the refcount on every call, and pins the buffer in shared mode. advance only mutates the in-place ptr/len/cap fields, avoiding that allocation/refcount churn on the TX hot path. The byte data itself is not copied by either path.
2026-09-02 09:09:17 +00:00 · 2026-07-01 23:19:34 +08:00
parent 7756a15cbe
commit f24735a86f
5 changed files with 130 additions and 11 deletions
@@ -1,4 +1,47 @@
-# TX Throughput Benchmark
+# Benchmarks
+
+Criterion benchmarks for EasyTier hot paths.
+
+| Bench                       | What it measures                                                                 |
+| --------------------------- | -------------------------------------------------------------------------------- |
+| `tx_throughput`             | End-to-end TX injection path through `peer_manager::send_msg_by_ip`              |
+| `packet_bytes_extraction`   | `ZCPacket::payload_bytes` / `tunnel_payload_bytes` extraction (advance hot path)  |
+
+## Packet Bytes Extraction
+
+Criterion benchmark for `ZCPacket` bytes extraction — the methods touched by the
+`advance`-based slicing refactor. Measures `payload_bytes` and
+`tunnel_payload_bytes` at two payload sizes (1280, 4096). Setup
+(`ZCPacket::new_with_payload`) runs in the benchmark harness's preparation
+phase and is excluded from the timed region, so the numbers reflect only the
+extraction call.
+
+### Quick start
+
+```bash
+cargo bench --bench packet_bytes_extraction
+```
+
+Smoke run:
+
+```bash
+PACKET_BYTES_MEASUREMENT_SECS=2 \
+PACKET_BYTES_WARMUP_SECS=1 \
+PACKET_BYTES_SAMPLE_SIZE=10 \
+cargo bench --bench packet_bytes_extraction -- --quiet
+```
+
+### Environment variables
+
+| Variable                        | Default | Notes                        |
+| ------------------------------- | ------- | ---------------------------- |
+| `PACKET_BYTES_MEASUREMENT_SECS` | `10`    | Criterion `measurement_time` |
+| `PACKET_BYTES_WARMUP_SECS`      | `3`     | Criterion `warm_up_time`     |
+| `PACKET_BYTES_SAMPLE_SIZE`      | `10`    | Criterion `sample_size` (min 10) |
+
+---
+
+## TX Throughput Benchmark

 Criterion benchmark for EasyTier's TX injection path (`peer_manager::send_msg_by_ip`).

@@ -0,0 +1,65 @@
+use std::hint::black_box;
+use std::time::Duration;
+
+use criterion::{BatchSize, Criterion, Throughput, criterion_group, criterion_main};
+
+use easytier::tunnel::packet_def::ZCPacket;
+
+const PAYLOAD_SIZES: &[usize] = &[1280, 4096];
+
+fn env_parse<T: std::str::FromStr>(key: &str, default: T) -> T {
+    std::env::var(key)
+        .ok()
+        .and_then(|v| v.parse().ok())
+        .unwrap_or(default)
+}
+
+fn bench_payload_bytes(c: &mut Criterion) {
+    let mut group = c.benchmark_group("payload_bytes");
+    for &size in PAYLOAD_SIZES {
+        let data = vec![0u8; size];
+        group.throughput(Throughput::Bytes(size as u64));
+        group.bench_with_input(format!("{size}"), &data, |b, data| {
+            b.iter_batched(
+                || ZCPacket::new_with_payload(black_box(data)),
+                |p| black_box(p).payload_bytes(),
+                BatchSize::SmallInput,
+            )
+        });
+    }
+    group.finish();
+}
+
+fn bench_tunnel_payload_bytes(c: &mut Criterion) {
+    let mut group = c.benchmark_group("tunnel_payload_bytes");
+    for &size in PAYLOAD_SIZES {
+        let data = vec![0u8; size];
+        group.throughput(Throughput::Bytes(size as u64));
+        group.bench_with_input(format!("{size}"), &data, |b, data| {
+            b.iter_batched(
+                || ZCPacket::new_with_payload(black_box(data)),
+                |p| black_box(p).tunnel_payload_bytes(),
+                BatchSize::SmallInput,
+            )
+        });
+    }
+    group.finish();
+}
+
+fn criterion_config() -> Criterion {
+    let measurement_secs = env_parse("PACKET_BYTES_MEASUREMENT_SECS", 10u64);
+    let warmup_secs = env_parse("PACKET_BYTES_WARMUP_SECS", 3u64);
+    let sample_size = env_parse("PACKET_BYTES_SAMPLE_SIZE", 10usize).max(10);
+
+    Criterion::default()
+        .measurement_time(Duration::from_secs(measurement_secs))
+        .warm_up_time(Duration::from_secs(warmup_secs))
+        .sample_size(sample_size)
+}
+
+criterion_group! {
+    name = benches;
+    config = criterion_config();
+    targets = bench_payload_bytes, bench_tunnel_payload_bytes
+}
+criterion_main!(benches);