quic: disable send fairness

quic-client/src/nonblocking/quic_client.rs

@@ -19,7 +19,7 @@ use {
     solana_measure::measure::Measure,
     solana_net_utils::{SocketConfig, VALIDATOR_PORT_RANGE},
     solana_quic_definitions::{
-        QUIC_CONNECTION_HANDSHAKE_TIMEOUT, QUIC_KEEP_ALIVE, QUIC_MAX_TIMEOUT,
+        QUIC_CONNECTION_HANDSHAKE_TIMEOUT, QUIC_KEEP_ALIVE, QUIC_MAX_TIMEOUT, QUIC_SEND_FAIRNESS,
     },
     solana_rpc_client_api::client_error::ErrorKind as ClientErrorKind,
     solana_streamer::nonblocking::quic::ALPN_TPU_PROTOCOL_ID,
@@ -105,6 +105,7 @@ impl QuicLazyInitializedEndpoint {
         let timeout = IdleTimeout::try_from(QUIC_MAX_TIMEOUT).unwrap();
         transport_config.max_idle_timeout(Some(timeout));
         transport_config.keep_alive_interval(Some(QUIC_KEEP_ALIVE));
+        transport_config.send_fairness(QUIC_SEND_FAIRNESS);
         config.transport_config(Arc::new(transport_config));
 
         endpoint.set_default_client_config(config);

sdk/quic-definitions/src/lib.rs

@@ -19,6 +19,14 @@ pub const QUIC_MAX_STAKED_CONCURRENT_STREAMS: usize = 512;
 pub const QUIC_MAX_TIMEOUT: Duration = Duration::from_secs(2);
 pub const QUIC_KEEP_ALIVE: Duration = Duration::from_secs(1);
 
+// Disable Quic send fairness.
+// When set to false, streams are still scheduled based on priority,
+// but once a chunk of a stream has been written out, quinn tries to complete
+// the stream instead of trying to round-robin balance it among the streams
+// with the same priority.
+// See https://github.com/quinn-rs/quinn/pull/2002.
+pub const QUIC_SEND_FAIRNESS: bool = false;
+
 // Based on commonly-used handshake timeouts for various TCP
 // applications. Different applications vary, but most seem to
 // be in the 30-60 second range

streamer/src/nonblocking/testing_utilities.rs

@@ -20,7 +20,7 @@ use {
     solana_keypair::Keypair,
     solana_net_utils::bind_to_localhost,
     solana_perf::packet::PacketBatch,
-    solana_quic_definitions::{QUIC_KEEP_ALIVE, QUIC_MAX_TIMEOUT},
+    solana_quic_definitions::{QUIC_KEEP_ALIVE, QUIC_MAX_TIMEOUT, QUIC_SEND_FAIRNESS},
     solana_tls_utils::{new_dummy_x509_certificate, tls_client_config_builder},
     std::{
         net::{SocketAddr, UdpSocket},
@@ -46,6 +46,7 @@ pub fn get_client_config(keypair: &Keypair) -> ClientConfig {
     let timeout = IdleTimeout::try_from(QUIC_MAX_TIMEOUT).unwrap();
     transport_config.max_idle_timeout(Some(timeout));
     transport_config.keep_alive_interval(Some(QUIC_KEEP_ALIVE));
+    transport_config.send_fairness(QUIC_SEND_FAIRNESS);
     config.transport_config(Arc::new(transport_config));
 
     config

tpu-client-next/src/quic_networking.rs

@@ -5,7 +5,7 @@ use {
         crypto::rustls::QuicClientConfig, ClientConfig, Connection, Endpoint, IdleTimeout,
         TransportConfig,
     },
-    solana_quic_definitions::{QUIC_KEEP_ALIVE, QUIC_MAX_TIMEOUT},
+    solana_quic_definitions::{QUIC_KEEP_ALIVE, QUIC_MAX_TIMEOUT, QUIC_SEND_FAIRNESS},
     solana_streamer::nonblocking::quic::ALPN_TPU_PROTOCOL_ID,
     solana_tls_utils::tls_client_config_builder,
     std::{net::SocketAddr, sync::Arc},
@@ -35,6 +35,7 @@ pub(crate) fn create_client_config(client_certificate: QuicClientCertificate) ->
         let timeout = IdleTimeout::try_from(QUIC_MAX_TIMEOUT).unwrap();
         res.max_idle_timeout(Some(timeout));
         res.keep_alive_interval(Some(QUIC_KEEP_ALIVE));
+        res.send_fairness(QUIC_SEND_FAIRNESS);
 
         res
     };