enricobuehler
c24b571e37
ci / rust (push) Has been cancelled
First increment of the 1 Gbps send-path rework (the measured bottleneck): the native data plane did one send() syscall per packet — at ~125k pkt/s (1 Gbps wire) that burns a core on syscalls. Port the proven GameStream sendmmsg path into the core Transport seam. - Transport gains `send_batch(&[&[u8]]) -> usize` (count handed to the kernel; caller counts the rest as send-buffer drops). Default = the scalar send loop (loopback transport + non-Linux). - UdpTransport overrides it on Linux with `sendmmsg` (64 datagrams/syscall); the connected socket needs no per-message address. Non-blocking-aware: a full send buffer yields a short count / EAGAIN, and we stop + report what went out rather than block or retry (same lossy, FEC-protected contract as send()). - Session::submit_frame seals every shard then hands the whole frame to send_batch in ONE call instead of looping send() — ~64x fewer syscalls per frame on the native + GameStream-over-core paths; send_dropped accounting preserved (total - sent). ~125k → ~2k syscalls/sec at 1 Gbps line rate. Verified: new loopback-UDP test send_batch_delivers_over_loopback (100 batched packets arrive intact, datagram boundaries preserved); full core suite + clippy + fmt green. Next increments: a paced send thread (microburst shaping so a real NIC doesn't drop line-rate bursts) and recvmmsg on the client. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>