Add configurable batch flush threshold to SpinSink. When threshold > 1,
MpscTunnelSender::send accumulates packets in FramedWriter's BufList
without flushing. After N packets, poll_flush triggers a single writev()
syscall instead of N individual write() syscalls.
Implementation:
- SpinSink: pending_count + batch_threshold atomics
- MpscTunnelSender::send: flush every N packets via writev
- Default threshold=1 (per-packet flush, safe for handshake/control)
- Settable via set_batch_threshold() through PeerConn → Peer → PeerManager
- Bench: HOTPATH_BATCH env var, set after convergence
Batch threshold must be 1 during handshake (control packets are
request-response, can't be delayed). Bench sets threshold=8 only after
routes converge.
Benchmark (no hotpath, 3 runs avg):
TCP batch=1: 985K pps
TCP batch=8: 1,053K pps (+7%)
Ring: unchanged (flush is no-op for RingSink)
UDP: unchanged (flush is no-op for RingSink)
MpscTunnelSender::send avg: 343ns → 213ns (-38%, with hotpath) —
writev writes 8 Bytes in one syscall vs 8 write() calls.
All 210 peers tests pass. 6 netns tests fail (require root, unchanged).
TCP tunnel uses FramedWriter (not RingSink), but start_send is still
sync (writes to BufList in memory). poll_flush does actual TCP write
syscall — noop_waker returns Ok for Pending (data stays in BufList,
flushed on next send when BufList >= 64).
Add TCP benchmark support via HOTPATH_TUNNEL=tcp. Note: TCP/UDP
convergence requires netns in bench environment (connector multi-bind
address behavior doesn't work for localhost without namespaces).
All 210 peers tests pass. Ring tunnel benchmark: 234K -> 508K pps (+117%).
UDP tunnel uses RingSink internally (same as ring tunnel). Extend
direct mode to include UDP. Fix poll_flush Pending to return Ok.
Add UDP benchmark support via HOTPATH_TUNNEL=udp env variable.
All 208 peers tests pass. Netns tests unchanged (require root).
FuturesUnordered-based pipeline to overlap encrypt with mpsc_send.
Tested depths 1/4/8/16: max +1.6% at depth=4, within noise. Pipeline
has limited value because try_send fast path eliminates await gaps
that would allow overlap. Default remains depth=1 (serial).
Add #[global_allocator] behind feature flags so the bench can test
different allocators. Previously the example used glibc malloc by
default (easytier-core.rs sets jemalloc/mimalloc only for the bin
target, not examples).
Benchmark (4 threads, 1400B, 15s, clone mode):
glibc: 246K pps, 3.13us/pkt
jemalloc: 246K pps, 3.21us/pkt
mimalloc: 242K pps, 3.25us/pkt
All within noise. Single-threaded clone has low malloc contention;
~1500B small allocs are served efficiently by all tcaches.
fanyang