Add multi_thread_streams/cutoff support and Samba performance tuning

- Add multi_thread_streams (default 4) and multi_thread_cutoff (default "50M")
  fields to ReadConfig, wired into rclone mount args
- Expose both fields in Web UI config editor under Read Tuning section
- Add Samba performance options: TCP_NODELAY, large readwrite, max xmit
- Update config.toml.default with new fields and sftp_connections guidance

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/config.rs

@@ -118,6 +118,12 @@ pub struct ReadConfig {
     /// In-memory buffer size (e.g. "256M").
     #[serde(default = "default_buffer_size")]
     pub buffer_size: String,
+    /// Number of parallel SFTP streams for single-file downloads (rclone --multi-thread-streams).
+    #[serde(default = "default_multi_thread_streams")]
+    pub multi_thread_streams: u32,
+    /// Minimum file size to trigger multi-thread download (e.g. "50M").
+    #[serde(default = "default_multi_thread_cutoff")]
+    pub multi_thread_cutoff: String,
 }
 
 /// Bandwidth control.
@@ -292,6 +298,12 @@ fn default_read_ahead() -> String {
 fn default_buffer_size() -> String {
     "256M".into()
 }
+fn default_multi_thread_streams() -> u32 {
+    4
+}
+fn default_multi_thread_cutoff() -> String {
+    "50M".into()
+}
 fn default_bw_zero() -> String {
     "0".into()
 }
@@ -417,6 +429,8 @@ impl Config {
         writeln!(out, "chunk_limit = {:?}", self.read.chunk_limit).unwrap();
         writeln!(out, "read_ahead = {:?}", self.read.read_ahead).unwrap();
         writeln!(out, "buffer_size = {:?}", self.read.buffer_size).unwrap();
+        writeln!(out, "multi_thread_streams = {}", self.read.multi_thread_streams).unwrap();
+        writeln!(out, "multi_thread_cutoff = {:?}", self.read.multi_thread_cutoff).unwrap();
         writeln!(out).unwrap();
 
         // --- Bandwidth ---
@@ -690,6 +704,8 @@ mount_point = "/mnt/photos"
         assert_eq!(config.read.chunk_limit, "1G");
         assert_eq!(config.read.read_ahead, "512M");
         assert_eq!(config.read.buffer_size, "256M");
+        assert_eq!(config.read.multi_thread_streams, 4);
+        assert_eq!(config.read.multi_thread_cutoff, "50M");
 
         assert_eq!(config.bandwidth.limit_up, "0");
         assert_eq!(config.bandwidth.limit_down, "0");
@@ -994,6 +1010,8 @@ mount_point = "/mnt/photos"
         assert_eq!(config.cache.dir, config2.cache.dir);
         assert_eq!(config.cache.max_size, config2.cache.max_size);
         assert_eq!(config.read.chunk_size, config2.read.chunk_size);
+        assert_eq!(config.read.multi_thread_streams, config2.read.multi_thread_streams);
+        assert_eq!(config.read.multi_thread_cutoff, config2.read.multi_thread_cutoff);
         assert_eq!(config.bandwidth.adaptive, config2.bandwidth.adaptive);
         assert_eq!(config.writeback.transfers, config2.writeback.transfers);
         assert_eq!(config.protocols.enable_smb, config2.protocols.enable_smb);

src/rclone/mount.rs

@@ -66,6 +66,13 @@ pub fn build_mount_args(config: &Config, share: &ShareConfig, rc_port: u16) -> V
     args.push("--vfs-read-ahead".into());
     args.push(config.read.read_ahead.clone());
 
+    // Multi-thread download: splits large files across N parallel SFTP streams
+    args.push("--multi-thread-streams".into());
+    args.push(config.read.multi_thread_streams.to_string());
+
+    args.push("--multi-thread-cutoff".into());
+    args.push(config.read.multi_thread_cutoff.clone());
+
     // Concurrent transfers for write-back
     args.push("--transfers".into());
     args.push(config.writeback.transfers.to_string());
@@ -240,6 +247,8 @@ mount_point = "/mnt/photos"
         assert!(args.contains(&"--dir-cache-time".to_string()));
         assert!(args.contains(&"1h".to_string()));
         assert!(args.contains(&"--buffer-size".to_string()));
+        assert!(args.contains(&"--multi-thread-streams".to_string()));
+        assert!(args.contains(&"--multi-thread-cutoff".to_string()));
         assert!(args.contains(&"--transfers".to_string()));
         assert!(args.contains(&"4".to_string()));
         assert!(args.contains(&"--rc".to_string()));

src/services/samba.rs

@@ -53,6 +53,13 @@ pub fn generate(config: &Config) -> Result<String> {
     writeln!(conf, "   printcap name = /dev/null")?;
     writeln!(conf, "   disable spoolss = yes")?;
     writeln!(conf)?;
+    writeln!(conf, "   # Performance tuning")?;
+    writeln!(conf, "   socket options = TCP_NODELAY IPTOS_THROUGHPUT SO_RCVBUF=131072 SO_SNDBUF=131072")?;
+    writeln!(conf, "   read raw = yes")?;
+    writeln!(conf, "   write raw = yes")?;
+    writeln!(conf, "   large readwrite = yes")?;
+    writeln!(conf, "   max xmit = 65535")?;
+    writeln!(conf)?;
 
     // Share sections — each share points at its own mount_point
     for share in &config.shares {
@@ -274,6 +281,9 @@ mount_point = "/mnt/photos"
         assert!(content.contains("server min protocol = SMB2_02"));
         assert!(content.contains("map to guest = Bad User"));
         assert!(content.contains("load printers = no"));
+        assert!(content.contains("socket options = TCP_NODELAY"));
+        assert!(content.contains("large readwrite = yes"));
+        assert!(content.contains("max xmit = 65535"));
     }
 
     #[test]

templates/config.toml.default

@@ -18,7 +18,7 @@ nas_user = "admin"
 # nas_key_file = "/root/.ssh/id_ed25519"
 # SFTP port
 sftp_port = 22
-# SFTP connection pool size
+# SFTP connection pool size (if multi_thread_streams=4, recommend >= 16)
 sftp_connections = 8
 
 # --- Additional NAS (uncomment to add) ---
@@ -49,6 +49,11 @@ chunk_limit = "1G"
 read_ahead = "512M"
 # In-memory buffer size
 buffer_size = "256M"
+# Number of parallel SFTP streams for single-file downloads (improves cold-read speed)
+# If using multi_thread_streams=4, set sftp_connections >= 16 for multi-file concurrency
+multi_thread_streams = 4
+# Minimum file size to trigger multi-thread download
+multi_thread_cutoff = "50M"
 
 [bandwidth]
 # Upload (write-back) speed limit ("0" = unlimited)

templates/web/tabs/config.html

@@ -295,6 +295,14 @@ if (window.Alpine) {
           <label>Buffer Size</label>
           <input type="text" x-model="config.read.buffer_size" placeholder="e.g. 256M">
         </div>
+        <div class="field-row">
+          <label>Multi-Thread Streams</label>
+          <input type="number" x-model.number="config.read.multi_thread_streams" min="1" max="64" placeholder="e.g. 4">
+        </div>
+        <div class="field-row">
+          <label>Multi-Thread Cutoff</label>
+          <input type="text" x-model="config.read.multi_thread_cutoff" placeholder="e.g. 50M">
+        </div>
       </div>
     </div>
   </section>