feat: Add NVTX markers for sglang EPD (#7079)

Signed-off-by: Wang, Yi <yi.a.wang@intel.com>

components/src/dynamo/sglang/request_handlers/multimodal/encode_worker_handler.py

@@ -17,6 +17,7 @@ from transformers import AutoTokenizer
 
 import dynamo.nixl_connect as connect
 from dynamo._core import Client, Context
+from dynamo.common.utils import nvtx_utils as _nvtx
 from dynamo.runtime import DistributedRuntime
 from dynamo.sglang.args import Config
 from dynamo.sglang.protocol import SglangMultimodalRequest
@@ -96,6 +97,7 @@ class MultimodalEncodeWorkerHandler(BaseWorkerHandler):
     def cleanup(self) -> None:
         pass
 
+    @_nvtx.range_decorator("mm:enc:generate", color="blue")
     async def generate(
         self, request: SglangMultimodalRequest, context: Context
     ) -> AsyncIterator[str]:
@@ -138,6 +140,7 @@ class MultimodalEncodeWorkerHandler(BaseWorkerHandler):
                     )
                 image_urls.append(mm_input.image_url)
 
+            with _nvtx.annotate("mm:enc:vision_encode", color="red"):
                 image_grid_dim, precomputed_embeddings = await self.encoder._encode(
                     image_urls
                 )
@@ -251,6 +254,7 @@ class MultimodalEncodeWorkerHandler(BaseWorkerHandler):
                 response_generator = await self.pd_worker_client.round_robin(
                     request.model_dump_json()
                 )
+                with _nvtx.annotate("mm:enc:embedding_transfer", color="purple"):
                     await readable.wait_for_completion()
 
                 async for response in response_generator:

components/src/dynamo/sglang/request_handlers/multimodal/worker_handler.py

@@ -4,7 +4,7 @@
 import asyncio
 import json
 import logging
-from typing import Any, AsyncIterator, Optional
+from typing import Any, AsyncIterator, Callable, Optional
 
 import sglang as sgl
 import torch
@@ -12,6 +12,7 @@ import torch
 import dynamo.nixl_connect as connect
 from dynamo._core import Client, Context
 from dynamo.common.constants import DisaggregationMode
+from dynamo.common.utils import nvtx_utils as _nvtx
 from dynamo.common.utils.engine_response import normalize_finish_reason
 from dynamo.sglang.args import Config
 from dynamo.sglang.protocol import (
@@ -113,7 +114,9 @@ class EmbeddingsProcessor:
             )
             self._connector = connect.Connector()
 
+        with _nvtx.annotate("mm:nixl:begin_read", color="blue"):
             read_op = await self._connector.begin_read(serialized_request, descriptor)
+        with _nvtx.annotate("mm:nixl:wait_completion", color="cyan"):
             await read_op.wait_for_completion()
 
         return embeddings, descriptor
@@ -317,23 +320,48 @@ class MultimodalWorkerHandler(BaseWorkerHandler):
             request: Multimodal request with input and parameters.
             context: Context object for cancellation handling.
         """
+        rng_pd = _nvtx.start_range("mm:pd:generate", color="green")
+        rng_ttft = _nvtx.start_range("mm:pd:ttft", color="yellow")
+        ttft_ended = False
+
+        def _end_ttft() -> None:
+            nonlocal ttft_ended
+            if not ttft_ended:
+                _nvtx.end_range(rng_ttft)
+                ttft_ended = True
+
         try:
             request = self._validate_and_parse_request(request)
 
             # Route to appropriate generation method based on serving mode
             if self.serving_mode == DisaggregationMode.DECODE:
-                async for output in self._generate_disaggregated(request):
+                rng_disagg = _nvtx.start_range("mm:pd:generate_disagg", color="red")
+                try:
+                    async for output in self._generate_disaggregated(
+                        request, _end_ttft
+                    ):
                         yield output
+                finally:
+                    _nvtx.end_range(rng_disagg)
             else:
-                async for output in self._generate_aggregated(request):
+                rng_agg = _nvtx.start_range("mm:pd:generate_agg", color="red")
+                try:
+                    async for output in self._generate_aggregated(request, _end_ttft):
                         yield output
+                finally:
+                    _nvtx.end_range(rng_agg)
 
         except Exception as e:
             logger.error(f"Error in multimodal generation: {e}", exc_info=True)
             yield ErrorResponseBuilder.build_error_response(e)
+        finally:
+            _end_ttft()
+            _nvtx.end_range(rng_pd)
 
     async def _generate_disaggregated(
-        self, request: SglangMultimodalRequest
+        self,
+        request: SglangMultimodalRequest,
+        end_ttft: Callable[[], None],
     ) -> AsyncIterator[str]:
         """Handle disaggregated mode generation"""
         input_ids = request.request.token_ids
@@ -357,11 +385,24 @@ class MultimodalWorkerHandler(BaseWorkerHandler):
             bootstrap_room=bootstrap_info["bootstrap_room"],
         )
 
+        rng_first = _nvtx.start_range("mm:dec:first_token", color="purple")
+        first_token = True
+        try:
             async for output in StreamProcessor.process_sglang_stream(decode_stream):
+                if first_token:
+                    end_ttft()
+                    _nvtx.end_range(rng_first)
+                    first_token = False
                 yield output
+        finally:
+            if first_token:
+                end_ttft()
+                _nvtx.end_range(rng_first)
 
     async def _generate_aggregated(
-        self, request: SglangMultimodalRequest
+        self,
+        request: SglangMultimodalRequest,
+        end_ttft: Callable[[], None],
     ) -> AsyncIterator[str]:
         """Handle aggregated mode generation"""
         input_ids = request.request.token_ids
@@ -370,6 +411,7 @@ class MultimodalWorkerHandler(BaseWorkerHandler):
 
         try:
             sampling_params = SglangUtils.build_sampling_params(request)
+            with _nvtx.annotate("mm:pd:load_multimodal", color="cyan"):
                 mm_items, combined_embeddings = await _build_mm_items(
                     request, self.embeddings_processor
                 )
@@ -387,8 +429,19 @@ class MultimodalWorkerHandler(BaseWorkerHandler):
                 stream=True,
             )
 
+            rng_first = _nvtx.start_range("mm:dec:first_token", color="purple")
+            first_token = True
+            try:
                 async for output in StreamProcessor.process_sglang_stream(agg_stream):
+                    if first_token:
+                        end_ttft()
+                        _nvtx.end_range(rng_first)
+                        first_token = False
                     yield output
+            finally:
+                if first_token:
+                    end_ttft()
+                    _nvtx.end_range(rng_first)
 
         except RuntimeError as e:
             if "shape mismatch" in str(e):
@@ -479,6 +532,15 @@ class MultimodalPrefillWorkerHandler(BaseWorkerHandler):
             disagg_request: Disaggregated multimodal request.
             context: Context object for cancellation handling.
         """
+        rng_bootstrap = _nvtx.start_range("mm:prefill:bootstrap", color="yellow")
+        bootstrap_ended = False
+
+        def _end_bootstrap() -> None:
+            nonlocal bootstrap_ended
+            if not bootstrap_ended:
+                _nvtx.end_range(rng_bootstrap)
+                bootstrap_ended = True
+
         bootstrap_room = None
         try:
             # Validate and parse request
@@ -492,6 +554,7 @@ class MultimodalPrefillWorkerHandler(BaseWorkerHandler):
                 "bootstrap_room": bootstrap_room,
             }
 
+            _end_bootstrap()
             yield json.dumps(bootstrap_info)
 
             # Process prefill generation
@@ -503,6 +566,8 @@ class MultimodalPrefillWorkerHandler(BaseWorkerHandler):
                 {"bootstrap_room": bootstrap_room} if bootstrap_room is not None else {}
             )
             yield ErrorResponseBuilder.build_error_response(e, extra_fields)
+        finally:
+            _end_bootstrap()
 
     def _validate_and_parse_disagg_request(
         self, disagg_request
@@ -529,9 +594,11 @@ class MultimodalPrefillWorkerHandler(BaseWorkerHandler):
         sampling_params = disagg_request.sampling_params
 
         # Process embeddings from encode worker using our embeddings processor
+        with _nvtx.annotate("mm:prefill:load_multimodal", color="cyan"):
             mm_items, _ = await _build_mm_items(request, self.embeddings_processor)
 
         # Start SGLang prefill generation (like regular SGLang)
+        with _nvtx.annotate("mm:prefill:engine_async_generate", color="blue"):
             results = await self.engine.async_generate(
                 input_ids=input_ids,
                 image_data=mm_items,

docs/features/multimodal/multimodal-sglang.md

@@ -403,6 +403,39 @@ export SGLANG_ENCODER_MM_LOAD_WORKERS=16
 
 Only applies to the EPD encode worker (which uses [SGLang's MMEncoder](https://github.com/sgl-project/sglang/blob/main/python/sglang/srt/disaggregation/encode_server.py) internally).
 
+## Profiling
+
+Dynamo's SGLang multimodal workers include NVTX markers for `nsys` profiling. They are disabled by default (zero overhead) and enabled by setting `DYN_NVTX=1`.
+
+```bash
+cd $DYNAMO_HOME/examples/backends/sglang
+DYN_NVTX=1 nsys profile --trace=cuda,nvtx -o profile.nsys-rep \
+  bash launch/multimodal_epd.sh ...
+```
+
+| ENV Variable | Default | Description |
+|---|---|---|
+| `DYN_NVTX` | `0` | Set to `1` to enable NVTX range/mark annotations in multimodal encode/prefill/decode worker paths for `nsys` profiling |
+
+Key NVTX ranges emitted:
+
+| Range | Worker | Description |
+|-------|--------|-------------|
+| `mm:enc:generate` | Encode | Full encode request lifetime |
+| `mm:enc:vision_encode` | Encode | Vision encode call (`MMEncoder._encode`) |
+| `mm:enc:embedding_transfer` | Encode | Embedding handoff to downstream worker |
+| `mm:nixl:begin_read` | PD (agg) / Prefill | Begin NIXL read operation for embeddings |
+| `mm:nixl:wait_completion` | PD (agg) / Prefill | Wait for NIXL embedding transfer completion |
+| `mm:pd:generate` | Aggregated worker / Decode worker (`MultimodalWorkerHandler`) | Full worker-side request lifetime |
+| `mm:pd:generate_agg` | PD (agg) | Aggregated generation path |
+| `mm:pd:load_multimodal` | PD (agg) | Build multimodal items from transferred embeddings |
+| `mm:pd:generate_disagg` | Decode worker (disagg entrypoint) | Disaggregated generation path |
+| `mm:prefill:bootstrap` | Prefill (disagg) | Bootstrap coordination path before returning `{bootstrap_host, bootstrap_port, bootstrap_room}` |
+| `mm:prefill:load_multimodal` | Prefill (disagg) | Build multimodal items from transferred embeddings in the prefill worker |
+| `mm:prefill:engine_async_generate` | Prefill (disagg) | SGLang prefill engine invocation (`engine.async_generate`) |
+| `mm:pd:ttft` | Aggregated worker / Decode worker (`MultimodalWorkerHandler`) | Worker-entry TTFT: from request arrival at this worker to first output token (excludes client->frontend->worker network transit) |
+| `mm:dec:first_token` | Aggregated worker / Decode worker (`MultimodalWorkerHandler`) | Decode-stage first-token range (starts when decode stream is launched; not worker-entry TTFT) |
+
 ## Known Limitations
 
 - **No Data URL support** - Only HTTP/HTTPS URLs supported; `data:image/...` base64 URLs not supported