feat(server): auto max_batch_total_tokens for flash att models (#630)

launcher/src/main.rs

@@ -184,8 +184,8 @@ struct Args {
     /// depends on other parameters like if you're using quantization, flash attention
     /// or the model implementation, text-generation-inference cannot infer this number
     /// automatically.
-    #[clap(default_value = "16000", long, env)]
-    max_batch_total_tokens: u32,
+    #[clap(long, env)]
+    max_batch_total_tokens: Option<u32>,
 
     /// This setting defines how many tokens can be passed before forcing the waiting
     /// queries to be put on the batch (if the size of the batch allows for it).
@@ -369,12 +369,6 @@ fn shard_manager(
     // Copy current process env
     let mut envs: Vec<(OsString, OsString)> = env::vars_os().collect();
 
-    // Use cuda allocator. It leads to less memory fragmentation
-    envs.push((
-        "PYTORCH_CUDA_ALLOC_CONF".into(),
-        "backend:cudaMallocAsync".into(),
-    ));
-
     // Torch Distributed Env vars
     envs.push(("RANK".into(), rank.to_string().into()));
     envs.push(("WORLD_SIZE".into(), world_size.to_string().into()));
@@ -428,7 +422,7 @@ fn shard_manager(
     }
 
     // Start process
-    tracing::info!("Starting shard {rank}");
+    tracing::info!("Starting shard");
     let mut p = match Command::new("text-generation-server")
         .args(shard_args)
         .envs(envs)
@@ -493,17 +487,17 @@ fn shard_manager(
         if shutdown.load(Ordering::SeqCst) {
             p.kill().unwrap();
             let _ = p.wait();
-            tracing::info!("Shard {rank} terminated");
+            tracing::info!("Shard terminated");
             return;
         }
 
         // Shard is ready
         if uds.exists() && !ready {
-            tracing::info!("Shard {rank} ready in {:?}", start_time.elapsed());
+            tracing::info!("Shard ready in {:?}", start_time.elapsed());
             status_sender.send(ShardStatus::Ready).unwrap();
             ready = true;
         } else if !ready && wait_time.elapsed() > Duration::from_secs(10) {
-            tracing::info!("Waiting for shard {rank} to be ready...");
+            tracing::info!("Waiting for shard to be ready...");
             wait_time = Instant::now();
         }
         sleep(Duration::from_millis(100));
@@ -860,8 +854,6 @@ fn spawn_webserver(
         args.max_total_tokens.to_string(),
         "--max-batch-prefill-tokens".to_string(),
         args.max_batch_prefill_tokens.to_string(),
-        "--max-batch-total-tokens".to_string(),
-        args.max_batch_total_tokens.to_string(),
         "--waiting-served-ratio".to_string(),
         args.waiting_served_ratio.to_string(),
         "--max-waiting-tokens".to_string(),
@@ -878,6 +870,12 @@ fn spawn_webserver(
         args.model_id,
     ];
 
+    // Model optional max batch total tokens
+    if let Some(max_batch_total_tokens) = args.max_batch_total_tokens {
+        router_args.push("--max-batch-total-tokens".to_string());
+        router_args.push(max_batch_total_tokens.to_string());
+    }
+
     // Model optional revision
     if let Some(ref revision) = args.revision {
         router_args.push("--revision".to_string());
@@ -1036,18 +1034,7 @@ fn main() -> Result<(), LauncherError> {
             args.max_batch_prefill_tokens, args.max_input_length
         )));
     }
-    if args.max_batch_prefill_tokens > args.max_batch_total_tokens {
-        return Err(LauncherError::ArgumentValidation(format!(
-            "`max_batch_prefill_tokens` must be <= `max_batch_total_tokens`. Given: {} and {}",
-            args.max_batch_prefill_tokens, args.max_batch_total_tokens
-        )));
-    }
-    if args.max_total_tokens as u32 > args.max_batch_total_tokens {
-        return Err(LauncherError::ArgumentValidation(format!(
-            "`max_total_tokens` must be <= `max_batch_total_tokens`. Given: {} and {}",
-            args.max_total_tokens, args.max_batch_total_tokens
-        )));
-    }
+
     if args.validation_workers == 0 {
         return Err(LauncherError::ArgumentValidation(
             "`validation_workers` must be > 0".to_string(),
@@ -1065,6 +1052,21 @@ fn main() -> Result<(), LauncherError> {
         tracing::info!("Sharding model on {num_shard} processes");
     }
 
+    if let Some(ref max_batch_total_tokens) = args.max_batch_total_tokens {
+        if args.max_batch_prefill_tokens > *max_batch_total_tokens {
+            return Err(LauncherError::ArgumentValidation(format!(
+                "`max_batch_prefill_tokens` must be <= `max_batch_total_tokens`. Given: {} and {}",
+                args.max_batch_prefill_tokens, max_batch_total_tokens
+            )));
+        }
+        if args.max_total_tokens as u32 > *max_batch_total_tokens {
+            return Err(LauncherError::ArgumentValidation(format!(
+                "`max_total_tokens` must be <= `max_batch_total_tokens`. Given: {} and {}",
+                args.max_total_tokens, max_batch_total_tokens
+            )));
+        }
+    }
+
     // Signal handler
     let running = Arc::new(AtomicBool::new(true));
     let r = running.clone();

proto/generate.proto

@@ -198,9 +198,10 @@ message DecodeResponse {
 message WarmupRequest {
     /// Batch to warmup on
     Batch batch = 1;
-    /// Maximum number of tokens that the client will send
-    uint32 max_total_tokens = 2;
 }
 
 /// Empty response
-message WarmupResponse {}
+message WarmupResponse {
+    /// Maximum number of tokens supported by the model
+    optional uint32 max_supported_total_tokens = 1;
+}

router/client/src/client.rs

@@ -103,8 +103,7 @@ impl Client {
         &mut self,
         max_input_length: u32,
         max_prefill_tokens: u32,
-        max_total_tokens: u32,
-    ) -> Result<()> {
+    ) -> Result<Option<u32>> {
         let mut n_tokens = 0;
         let mut requests = Vec::new();
 
@@ -143,13 +142,9 @@ impl Client {
             max_tokens: 0,
         };
 
-        let request = tonic::Request::new(WarmupRequest {
-            batch: Some(batch),
-            max_total_tokens,
-        })
-        .inject_context();
-        self.stub.warmup(request).await?.into_inner();
-        Ok(())
+        let request = tonic::Request::new(WarmupRequest { batch: Some(batch) }).inject_context();
+        let response = self.stub.warmup(request).await?.into_inner();
+        Ok(response.max_supported_total_tokens)
     }
 
     /// Generate one token for each request in the given batch

router/client/src/sharded_client.rs

@@ -95,14 +95,11 @@ impl ShardedClient {
         &mut self,
         max_input_length: u32,
         max_prefill_tokens: u32,
-        max_total_tokens: u32,
-    ) -> Result<()> {
+    ) -> Result<Option<u32>> {
         let futures: Vec<_> = self
             .clients
             .iter_mut()
-            .map(|client| {
-                Box::pin(client.warmup(max_input_length, max_prefill_tokens, max_total_tokens))
-            })
+            .map(|client| Box::pin(client.warmup(max_input_length, max_prefill_tokens)))
             .collect();
         // all shards return the same message
         join_all(futures).await.pop().unwrap()

router/src/infer.rs

@@ -53,7 +53,7 @@ impl Infer {
         generation_health: Arc<AtomicBool>,
     ) -> Self {
         // Infer shared state
-        let queue = Queue::new(requires_padding);
+        let queue = Queue::new(requires_padding, 16);
         let shared = Arc::new(Shared {
             batching_task: Notify::new(),
         });

router/src/main.rs

@@ -37,8 +37,8 @@ struct Args {
     waiting_served_ratio: f32,
     #[clap(default_value = "4096", long, env)]
     max_batch_prefill_tokens: u32,
-    #[clap(default_value = "16000", long, env)]
-    max_batch_total_tokens: u32,
+    #[clap(long, env)]
+    max_batch_total_tokens: Option<u32>,
     #[clap(default_value = "20", long, env)]
     max_waiting_tokens: usize,
     #[clap(default_value = "0.0.0.0", long, env)]
@@ -110,18 +110,22 @@ fn main() -> Result<(), RouterError> {
     if max_input_length as u32 > max_batch_prefill_tokens {
         return Err(RouterError::ArgumentValidation(format!("`max_batch_prefill_tokens` must be >= `max_input_length`. Given: {max_batch_prefill_tokens} and {max_input_length}")));
     }
-    if max_batch_prefill_tokens > max_batch_total_tokens {
-        return Err(RouterError::ArgumentValidation(format!("`max_batch_prefill_tokens` must be <= `max_batch_total_tokens`. Given: {max_batch_prefill_tokens} and {max_batch_total_tokens}")));
-    }
-    if max_total_tokens as u32 > max_batch_total_tokens {
-        return Err(RouterError::ArgumentValidation(format!("`max_total_tokens` must be <= `max_batch_total_tokens`. Given: {max_total_tokens} and {max_batch_total_tokens}")));
-    }
+
     if validation_workers == 0 {
         return Err(RouterError::ArgumentValidation(
             "`validation_workers` must be > 0".to_string(),
         ));
     }
 
+    if let Some(ref max_batch_total_tokens) = max_batch_total_tokens {
+        if max_batch_prefill_tokens > *max_batch_total_tokens {
+            return Err(RouterError::ArgumentValidation(format!("`max_batch_prefill_tokens` must be <= `max_batch_total_tokens`. Given: {max_batch_prefill_tokens} and {max_batch_total_tokens}")));
+        }
+        if max_total_tokens as u32 > *max_batch_total_tokens {
+            return Err(RouterError::ArgumentValidation(format!("`max_total_tokens` must be <= `max_batch_total_tokens`. Given: {max_total_tokens} and {max_batch_total_tokens}")));
+        }
+    }
+
     // CORS allowed origins
     // map to go inside the option and then map to parse from String to HeaderValue
     // Finally, convert to AllowOrigin
@@ -210,14 +214,35 @@ fn main() -> Result<(), RouterError> {
 
             // Warmup model
             tracing::info!("Warming up model");
-            sharded_client
-                .warmup(
-                    max_input_length as u32,
-                    max_batch_prefill_tokens,
-                    max_batch_total_tokens,
-                )
+            let max_supported_batch_total_tokens = match sharded_client
+                .warmup(max_input_length as u32, max_batch_prefill_tokens)
                 .await
-                .map_err(RouterError::Warmup)?;
+                .map_err(RouterError::Warmup)?
+            {
+                // Older models do not support automatic max-batch-total-tokens
+                None => {
+                    let max_batch_total_tokens = max_batch_total_tokens.unwrap_or(
+                        16000.max((max_total_tokens as u32).max(max_batch_prefill_tokens)),
+                    );
+                    tracing::warn!("Model does not support automatic max batch total tokens");
+                    max_batch_total_tokens
+                }
+                // Flash attention models return their max supported total tokens
+                Some(max_supported_batch_total_tokens) => {
+                    // Warn if user added his own max-batch-total-tokens as we will ignore it
+                    if max_batch_total_tokens.is_some() {
+                        tracing::warn!(
+                            "`--max-batch-total-tokens` is deprecated for Flash \
+                        Attention models."
+                        );
+                        tracing::warn!(
+                            "Inferred max batch total tokens: {max_supported_batch_total_tokens}"
+                        );
+                    }
+                    max_supported_batch_total_tokens
+                }
+            };
+            tracing::info!("Setting max batch total tokens to {max_supported_batch_total_tokens}");
             tracing::info!("Connected");
 
             let addr = match hostname.parse() {
@@ -240,7 +265,7 @@ fn main() -> Result<(), RouterError> {
                 max_total_tokens,
                 waiting_served_ratio,
                 max_batch_prefill_tokens,
-                max_batch_total_tokens,
+                max_supported_batch_total_tokens,
                 max_waiting_tokens,
                 sharded_client,
                 tokenizer,

router/src/queue.rs

@@ -33,12 +33,12 @@ pub(crate) struct Queue {
 }
 
 impl Queue {
-    pub(crate) fn new(requires_padding: bool) -> Self {
+    pub(crate) fn new(requires_padding: bool, block_size: u32) -> Self {
         // Create channel
         let (queue_sender, queue_receiver) = flume::unbounded();
 
         // Launch background queue task
-        tokio::spawn(queue_task(requires_padding, queue_receiver));
+        tokio::spawn(queue_task(requires_padding, block_size, queue_receiver));
 
         Self { queue_sender }
     }
@@ -81,8 +81,12 @@ impl Queue {
 }
 
 // Background task responsible of the queue state
-async fn queue_task(requires_padding: bool, receiver: flume::Receiver<QueueCommand>) {
-    let mut state = State::new(requires_padding);
+async fn queue_task(
+    requires_padding: bool,
+    block_size: u32,
+    receiver: flume::Receiver<QueueCommand>,
+) {
+    let mut state = State::new(requires_padding, block_size);
 
     while let Ok(cmd) = receiver.recv_async().await {
         match cmd {
@@ -119,15 +123,19 @@ struct State {
 
     /// Whether the model is using padding
     requires_padding: bool,
+
+    /// Paged Attention block size
+    block_size: u32,
 }
 
 impl State {
-    fn new(requires_padding: bool) -> Self {
+    fn new(requires_padding: bool, block_size: u32) -> Self {
         Self {
             entries: VecDeque::with_capacity(128),
             next_id: 0,
             next_batch_id: 0,
             requires_padding,
+            block_size,
         }
     }
 
@@ -187,10 +195,21 @@ impl State {
                 max_input_length = max_input_length.max(entry.request.input_length);
                 prefill_tokens = (batch_requests.len() + 1) as u32 * max_input_length
             } else {
-                prefill_tokens += entry.request.input_length;
+                // pad to block size
+                prefill_tokens += ((entry.request.input_length + self.block_size - 1)
+                    / self.block_size)
+                    * self.block_size;
             }
 
-            decode_tokens += entry.request.stopping_parameters.max_new_tokens;
+            if self.requires_padding {
+                decode_tokens += entry.request.stopping_parameters.max_new_tokens;
+            } else {
+                // pad to block size
+                decode_tokens +=
+                    ((entry.request.stopping_parameters.max_new_tokens + self.block_size - 1)
+                        / self.block_size)
+                        * self.block_size;
+            }
 
             if prefill_tokens > prefill_token_budget
                 || (prefill_tokens + decode_tokens) > token_budget
@@ -321,7 +340,7 @@ mod tests {
 
     #[test]
     fn test_append() {
-        let mut state = State::new(false);
+        let mut state = State::new(false, 1);
         let (entry, _guard) = default_entry();
 
         assert_eq!(state.next_id, 0);
@@ -337,7 +356,7 @@ mod tests {
 
     #[test]
     fn test_next_batch_empty() {
-        let mut state = State::new(false);
+        let mut state = State::new(false, 1);
 
         assert!(state.next_batch(None, 1, 1).is_none());
         assert!(state.next_batch(Some(1), 1, 1).is_none());
@@ -345,7 +364,7 @@ mod tests {
 
     #[test]
     fn test_next_batch_min_size() {
-        let mut state = State::new(false);
+        let mut state = State::new(false, 1);
         let (entry1, _guard1) = default_entry();
         let (entry2, _guard2) = default_entry();
         state.append(entry1);
@@ -377,7 +396,7 @@ mod tests {
 
     #[test]
     fn test_next_batch_token_budget() {
-        let mut state = State::new(false);
+        let mut state = State::new(false, 1);
         let (entry1, _guard1) = default_entry();
         let (entry2, _guard2) = default_entry();
         state.append(entry1);
@@ -410,14 +429,14 @@ mod tests {
 
     #[tokio::test]
     async fn test_queue_append() {
-        let queue = Queue::new(false);
+        let queue = Queue::new(false, 1);
         let (entry, _guard) = default_entry();
         queue.append(entry);
     }
 
     #[tokio::test]
     async fn test_queue_next_batch_empty() {
-        let queue = Queue::new(false);
+        let queue = Queue::new(false, 1);
 
         assert!(queue.next_batch(None, 1, 1).await.is_none());
         assert!(queue.next_batch(Some(1), 1, 1).await.is_none());
@@ -425,7 +444,7 @@ mod tests {
 
     #[tokio::test]
     async fn test_queue_next_batch_min_size() {
-        let queue = Queue::new(false);
+        let queue = Queue::new(false, 1);
         let (entry1, _guard1) = default_entry();
         let (entry2, _guard2) = default_entry();
         queue.append(entry1);
@@ -458,7 +477,7 @@ mod tests {
 
     #[tokio::test]
     async fn test_queue_next_batch_token_budget() {
-        let queue = Queue::new(false);
+        let queue = Queue::new(false, 1);
         let (entry1, _guard1) = default_entry();
         let (entry2, _guard2) = default_entry();
         queue.append(entry1);
@@ -483,7 +502,7 @@ mod tests {
 
     #[tokio::test]
     async fn test_queue_next_batch_dropped_receiver() {
-        let queue = Queue::new(false);
+        let queue = Queue::new(false, 1);
         let (entry, _) = default_entry();
         queue.append(entry);
 

server/text_generation_server/models/flash_causal_lm.py

@@ -710,14 +710,14 @@ class FlashCausalLM(Model):
     def batch_type(self) -> Type[FlashCausalLMBatch]:
         return FlashCausalLMBatch
 
-    def warmup(self, batch: FlashCausalLMBatch, max_total_tokens: int):
+    def warmup(self, batch: FlashCausalLMBatch):
         global CACHE_MANAGER
 
         torch.cuda.empty_cache()
+        torch.cuda.reset_peak_memory_stats(self.device)
         try:
             CACHE_MANAGER = CacheManager(
-                # Adds some wiggle room
-                math.ceil(max_total_tokens / BLOCK_SIZE) + 10,
+                batch.blocks,
                 self.num_layers,
                 self.num_kv_heads,
                 self.head_size,
@@ -727,11 +727,43 @@ class FlashCausalLM(Model):
             _, batch = self.generate_token(batch)
         except Exception as e:
             raise RuntimeError(
-                f"Not enough memory to handle {max_total_tokens} total tokens with {len(batch.input_ids)} "
-                f"prefill tokens. "
-                f"You need to decrease `--max-batch-total-tokens` or `--max-batch-prefill-tokens`"
+                f"Not enough memory to handle {len(batch.input_ids)} prefill tokens. "
+                f"You need to decrease `--max-batch-prefill-tokens`"
             ) from e
+
+        # Inspired by the original implementation in [vllm](https://github.com/vllm-project/vllm)
+        # Calculate the number of blocks that can be allocated with the
+        # profiled peak memory.
+        torch.cuda.synchronize(self.device)
+        peak_memory = torch.cuda.max_memory_reserved(self.device)
+
+        dtype_size = torch.tensor([], dtype=self.dtype).element_size()
+        cache_block_size = BLOCK_SIZE * self.num_kv_heads * self.head_size
+        total_cache_size = self.num_layers * cache_block_size * 2 * dtype_size
+
+        total_gpu_memory = torch.cuda.get_device_properties(self.device).total_memory
+
+        # 0.98 to add some wiggle room
+        num_blocks = (
+            int((total_gpu_memory * 0.98 - peak_memory) // total_cache_size)
+            # Add batch.blocks as we allocated it above, so it is included in the peak memory.
+            + batch.blocks
+        )
+
+        del CACHE_MANAGER
         del batch
+        torch.cuda.empty_cache()
+
+        CACHE_MANAGER = CacheManager(
+            num_blocks,
+            self.num_layers,
+            self.num_kv_heads,
+            self.head_size,
+            self.dtype,
+            self.device,
+        )
+
+        return int(num_blocks * BLOCK_SIZE)
 
     def decode(self, generated_ids: Union[torch.Tensor, List[int]]) -> str:
         return self.tokenizer.decode(
@@ -991,7 +1023,6 @@ class FlashCausalLM(Model):
 
         if stopped:
             del batch
-            torch.cuda.empty_cache()
             # No need to return a batch if we know that all requests stopped
             return generations, None
 

server/text_generation_server/models/model.py

@@ -58,8 +58,9 @@ class Model(ABC):
     def generate_token(self, batch: B) -> Tuple[List[GeneratedText], Optional[B]]:
         raise NotImplementedError
 
-    def warmup(self, batch: B, max_total_tokens: int):
+    def warmup(self, batch: B) -> Optional[int]:
         self.generate_token(batch)
+        return None
 
     def decode_token(
         self,

server/text_generation_server/server.py

@@ -51,21 +51,17 @@ class TextGenerationService(generate_pb2_grpc.TextGenerationServiceServicer):
         filtered_batch = batch.filter(request.request_ids)
         self.cache.set(filtered_batch)
 
-        if torch.cuda.is_available():
-            torch.cuda.empty_cache()
-
         return generate_pb2.FilterBatchResponse(batch=filtered_batch.to_pb())
 
     async def Warmup(self, request, context):
         batch = self.model.batch_type.from_pb(
             request.batch, self.model.tokenizer, self.model.dtype, self.model.device
         )
-        self.model.warmup(batch, request.max_total_tokens)
-
-        if torch.cuda.is_available():
-            torch.cuda.empty_cache()
+        max_supported_total_tokens = self.model.warmup(batch)
 
-        return generate_pb2.WarmupResponse()
+        return generate_pb2.WarmupResponse(
+            max_supported_total_tokens=max_supported_total_tokens
+        )
 
     async def Prefill(self, request, context):
         batch = self.model.batch_type.from_pb(
@@ -96,8 +92,6 @@ class TextGenerationService(generate_pb2_grpc.TextGenerationServiceServicer):
 
         if len(batches) > 1:
             batch = self.model.batch_type.concatenate(batches)
-            if torch.cuda.is_available():
-                torch.cuda.empty_cache()
         else:
             batch = batches[0]