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@fzyzcjy fzyzcjy commented Jun 2, 2025

Motivation

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Hello @fzyzcjy, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

Summary of Changes

Hello! Gemini here, providing a summary of this pull request to help everyone quickly understand the changes.

Based on the title "Minor add metrics to expert location updater" and the code changes, the primary intent of this PR is to introduce logging for P2P communication metrics within the expert location updating process. This seems aimed at providing visibility into the data transfer happening during this crucial step, likely for performance analysis and debugging.

The PR description body was empty, so I've inferred the motivation and modifications directly from the code changes.

Highlights

  • Add P2P Communication Metrics: Introduces logging to track the amount of data being sent and received via P2P operations (isend/irecv) during the expert location update process.
  • Conditional Logging: The new metrics logging is controlled by an environment variable, SGLANG_EXPERT_LOCATION_UPDATER_LOG_METRICS, allowing it to be enabled or disabled easily.
  • Detailed Metric Reporting: The logged metrics include byte counts aggregated per GPU, per node, for the current node, and cross-node, providing a detailed view of the communication patterns.
  • New Helper Functions: Adds private helper functions (_log_p2p_op_metrics, _get_direction_from_op, _group_by) to facilitate the calculation and logging of these metrics.

Changelog

  • python/sglang/srt/model_executor/expert_location_updater.py
    • Added imports for defaultdict, Optional, and einops (Diff 1).
    • Imported get_bool_env_var utility (Diff 2).
    • Added a check for the SGLANG_EXPERT_LOCATION_UPDATER_LOG_METRICS environment variable to enable/disable logging (Diff 3, line 65).
    • Passed world_size and log_metrics parameters to the update_expert_weights_single_layer function call (Diff 4, lines 91-92).
    • Added world_size and log_metrics parameters to the update_expert_weights_single_layer function signature (Diff 5, lines 108, 110).
    • Added a conditional call to the new _log_p2p_op_metrics function within the main loop if log_metrics is true (Diff 6, lines 142-148).
    • Added the _log_p2p_op_metrics function to calculate and log P2P communication statistics (Diff 7, lines 451-483).
    • Added the _get_direction_from_op helper function to identify P2P operation direction (Diff 7, lines 486-491).
    • Added the _group_by helper function for grouping items (Diff 7, lines 494-498).
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Code Review

This pull request introduces metrics logging for the expert location updater, controlled by an environment variable. The changes are well-localized, and the use of an environment variable to control logging is a good approach. The new helper functions for metric calculation are clear.

I have a couple of suggestions regarding type safety for world_size when metrics are enabled, and for adding a docstring to the new logging function to improve maintainability. Addressing these would enhance the robustness and clarity of the new functionality.

Summary of Findings

  • Type Safety for world_size: The world_size parameter in update_expert_weights_single_layer is Optional[int], but it's passed to _log_p2p_op_metrics which expects an int. This could lead to a TypeError if log_metrics is true and world_size is None. An assertion or stricter typing is recommended.
  • Documentation for New Metrics Function: The new _log_p2p_op_metrics function would benefit from a docstring explaining its purpose, parameters, and the metrics it logs, due to its internal complexity. I have lowered the severity of this finding since it is related to documentation.

Merge Readiness

The pull request is a good step towards adding valuable metrics. However, there's a medium-severity issue regarding potential type errors with world_size and a suggestion for improving maintainability with a docstring. I recommend addressing these points before merging to ensure robustness and clarity. As an AI, I am not authorized to approve pull requests; please ensure further review and approval from team members.

Comment on lines +108 to +110
world_size: Optional[int] = None,
debug: bool = False,
log_metrics: bool = False,
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medium

The world_size parameter is typed as Optional[int] with a default of None, and log_metrics defaults to False. However, if log_metrics is True, the _log_p2p_op_metrics function is called, which expects world_size to be an int (not None).

While the current primary call path from _update_expert_weights ensures world_size is an integer, if update_expert_weights_single_layer were called directly with log_metrics=True and world_size=None, it would lead to a TypeError inside _log_p2p_op_metrics.

To improve robustness, could we consider one of the following?

  1. If world_size is always expected to be an int when log_metrics is true, perhaps change its type hint here to int and ensure callers always provide it (removing the default None if appropriate).
  2. Add an assertion inside this function, before calling _log_p2p_op_metrics, to ensure world_size is not None when log_metrics is True.

An assertion would look like this (to be placed around line 142, before the if log_metrics: block or at the start of it):

if log_metrics:
    assert world_size is not None, "world_size must be provided when log_metrics is True"

This would make the dependency explicit and prevent runtime errors if this function's usage evolves.

if log_metrics:
    assert world_size is not None, "world_size must be provided when log_metrics is True"

@zhyncs zhyncs merged commit b6d0ce9 into sgl-project:main Jun 3, 2025
82 of 97 checks passed
jianan-gu pushed a commit to jianan-gu/sglang that referenced this pull request Jun 12, 2025
xwu-intel pushed a commit to xwu-intel/sglang that referenced this pull request Jun 17, 2025
walker-ai pushed a commit to walker-ai/sglang that referenced this pull request Jul 8, 2025
Merge branch 'sgl_20250610_sync_tag047 of git@code.alipay.com:Theta/SGLang.git into main

https://code.alipay.com/Theta/SGLang/pull_requests/52


Reviewed-by: 剑川 <jianchuan.gys@antgroup.com>


* [Bugfix] Fix slice operation when chunk size mismatch (sgl-project#6697)
* [Bugfix] Fix ChatCompletion endpoint of mini_lb when stream is set (sgl-project#6703)
* [CI] Fix setup of disaggregation with different tp (sgl-project#6706)
* [PD] Remove Unnecessary Exception Handling for FastQueue.get() (sgl-project#6712)
* Fuse routed_scaling_factor in DeepSeek (sgl-project#6710)
* Overlap two kernels in DeepSeek with communication (sgl-project#6711)
* Minor refactor two-batch overlap (sgl-project#6682)
* Speed up when having padding tokens two-batch overlap (sgl-project#6668)
* [Feature] Support Flashinfer fp8 blockwise GEMM kernel on Blackwell (sgl-project#6479)
* Fix LoRA bench (sgl-project#6719)
* temp
* Fix PP for Qwen3 MoE (sgl-project#6709)
* [feat] triton kernel for get_last_loc (sgl-project#6676)
* [fix] more mem for draft_extend cuda_graph (sgl-project#6726)
* [PD] bug fix:  Update status if nixl receiver send a a dummy req. (sgl-project#6720)
* Tune memory arguments on B200 (sgl-project#6718)
* Add DeepSeek-R1-0528 function call chat template (sgl-project#6725)
* refactor(tool call): Fix BaseFormatDetector tool_index issue and refactor `parse_streaming_increment` (sgl-project#6715)
* Add draft extend CUDA graph for Triton backend (sgl-project#6705)
* refactor apply_w8a8_block_fp8_linear in fp (sgl-project#6545)
* [PD] Support completion endpoint (sgl-project#6729)
* PD Rust LB (PO2) (sgl-project#6437)
* Super tiny enable sole usage of expert distribution metrics and update doc (sgl-project#6680)
* Support picking variants of EPLB algorithms (sgl-project#6728)
* Support tuning DeepEP configs (sgl-project#6742)
* [test] add ut and bm for get_last_loc (sgl-project#6746)
* Fix mem_fraction_static for AMD CI (sgl-project#6748)
* [fix][RL] Fix DeepSeekV3ForCausalLM.post_load_weights for multiple update weight (sgl-project#6265)
* Improve EPLB logical to physical dispatch map (sgl-project#6727)
* Update DeepSeek-R1-0528 function call chat template (sgl-project#6765)
* [PD] Optimize time out logic and add env var doc for mooncake (sgl-project#6761)
* Fix aiohttp 'Chunk too big' in bench_serving (sgl-project#6737)
* Support sliding window in triton backend (sgl-project#6509)
* Fix shared experts fusion error (sgl-project#6289)
* Fix one bug in the grouped-gemm triton kernel (sgl-project#6772)
* update llama4 chat template and pythonic parser (sgl-project#6679)
* feat(tool call): Enhance Llama32Detector for improved JSON parsing in non-stream (sgl-project#6784)
* Support token-level quantization for EP MoE (sgl-project#6782)
* Temporarily lower mmlu threshold for triton sliding window backend (sgl-project#6785)
* ci: relax test_function_call_required (sgl-project#6786)
* Add intel_amx backend for Radix Attention for CPU (sgl-project#6408)
* Fix incorrect LoRA weight loading for fused gate_up_proj (sgl-project#6734)
* fix(PD-disaggregation): Can not get local ip (sgl-project#6792)
* [FIX] mmmu bench serving result display error (sgl-project#6525) (sgl-project#6791)
* Bump torch to 2.7.0 (sgl-project#6788)
* chore: bump sgl-kernel v0.1.5 (sgl-project#6794)
* Improve profiler and integrate profiler in bench_one_batch_server (sgl-project#6787)
* chore: upgrade sgl-kernel v0.1.5 (sgl-project#6795)
* [Minor] Always append newline after image token when parsing chat message (sgl-project#6797)
* Update CI tests for Llama4 models (sgl-project#6421)
* [Feat] Enable PDL automatically on Hopper architecture (sgl-project#5981)
* chore: update blackwell docker (sgl-project#6800)
* misc: cache is_hopper_arch (sgl-project#6799)
* Remove contiguous before Flashinfer groupwise fp8 gemm (sgl-project#6804)
* Correctly abort the failed grammar requests & Improve the handling of abort (sgl-project#6803)
* [EP] Add cuda kernel for moe_ep_pre_reorder (sgl-project#6699)
* Add draft extend CUDA graph for flashinfer backend  (sgl-project#6805)
* Refactor CustomOp to avoid confusing bugs (sgl-project#5382)
* Tiny log prefill time (sgl-project#6780)
* Tiny fix EPLB assertion about rebalancing period and recorder window size (sgl-project#6813)
* Add simple utility to dump tensors for debugging (sgl-project#6815)
* Fix profiles do not have consistent names (sgl-project#6811)
* Speed up rebalancing when using non-static dispatch algorithms (sgl-project#6812)
* [1/2] Add Kernel support for Cutlass based Fused FP4 MoE (sgl-project#6093)
* [Router] Fix k8s Service Discovery (sgl-project#6766)
* Add CPU optimized kernels for topk and rope fusions  (sgl-project#6456)
* fix new_page_count_next_decode (sgl-project#6671)
* Fix wrong weight reference in dynamic EPLB (sgl-project#6818)
* Minor add metrics to expert location updater (sgl-project#6816)
* [Refactor] Rename `n_share_experts_fusion` as `num_fused_shared_experts` (sgl-project#6735)
* [FEAT] Add transformers backend support  (sgl-project#5929)
* [fix] recover auto-dispatch for rmsnorm and rope (sgl-project#6745)
* fix ep_moe_reorder kernel bugs (sgl-project#6858)
* [Refactor] Multimodal data processing for VLM (sgl-project#6659)
* Decoder-only Scoring API (sgl-project#6460)
* feat: add dp-rank to KV events (sgl-project#6852)
* Set `num_fused_shared_experts` as `num_shared_experts` when shared_experts fusion is not disabled (sgl-project#6736)
* Fix one missing arg in DeepEP (sgl-project#6878)
* Support LoRA in TestOpenAIVisionServer and fix fused kv_proj loading bug. (sgl-project#6861)
* support 1 shot allreduce  in 1-node and 2-node using mscclpp (sgl-project#6277)
* Fix Qwen3MoE missing token padding optimization (sgl-project#6820)
* Tiny update error hints (sgl-project#6846)
* Support layerwise rebalancing experts (sgl-project#6851)
* Tiny allow profiler API to auto create directory (sgl-project#6865)
* Support Blackwell DeepEP docker images (sgl-project#6868)
* [EP] Add cuda kernel for moe_ep_post_reorder (sgl-project#6837)
* [theta]merge 0605
* oai: fix openAI client error with single request via batch api (sgl-project#6170)
* [PD] Fix potential perf spike caused by tracker gc and optimize doc (sgl-project#6764)
* Use deepgemm instead of triton for fused_qkv_a_proj_with_mqa (sgl-project#6890)
* [CUTLASS-FP4-MOE]  Introduce CutlassMoEParams class for easy initialization of Cutlass Grouped Gems Metadata (sgl-project#6887)
* bugfix(OAI): Fix image_data processing for jinja chat templates (sgl-project#6877)
* [CPU] enable CI for PRs, add Dockerfile and auto build task (sgl-project#6458)
* AITER backend extension and workload optimizations (sgl-project#6838)
* [theta]merge
* [theta]merge
* [Feature] Support Flashinfer fmha on Blackwell (sgl-project#6930)
* Fix a bug in abort & Improve docstrings for abort (sgl-project#6931)
* Tiny support customize DeepEP max dispatch tokens per rank (sgl-project#6934)
* Sync the changes on cuda graph runners (sgl-project#6932)
* [PD] Optimize transfer queue forward logic for dummy rank (sgl-project#6922)
* [Refactor] image data process in bench_serving (sgl-project#6879)
* [fix] logical_to_all_physical_map index 256 is out of bounds in EP parallel. (sgl-project#6767)
* Add triton fused moe kernel config for E=257 on B200 (sgl-project#6939)
* [sgl-kernel] update deepgemm (sgl-project#6942)
* chore: bump sgl-kernel v0.1.6 (sgl-project#6943)
* Minor compile fused topk (sgl-project#6944)
* [Bugfix] pipeline parallelism and Eagle Qwen2 (sgl-project#6910)
* Tiny re-introduce profile id logging (sgl-project#6912)
* Add triton version as a fused_moe_triton config search key to avoid performace decrease in different Triton version (sgl-project#5955)
* reduce torch.zeros overhead in moe align block size kernel (sgl-project#6369)
* chore: upgrade sgl-kernel v0.1.6 (sgl-project#6945)
* add fbgemm moe grouped gemm kernel benchmark (sgl-project#6924)
* [Docker] Add docker file for SGL Router (sgl-project#6915)
* Disabling mixed chunked prefill when eagle is enabled (sgl-project#6874)
* Add canary for EPLB rebalancing (sgl-project#6895)
* Refactor global_server_args_dict (sgl-project#6866)
* Fuse routed scaling factor in topk_reduce kernel (sgl-project#6220)
* Update server timeout time in AMD CI. (sgl-project#6953)
* [misc] add is_cpu() (sgl-project#6950)
* Add H20 fused MoE kernel tuning configs for DeepSeek-R1/V3 (sgl-project#6885)
* Add a CUDA kernel for fusing mapping and weighted sum for MoE. (sgl-project#6916)
* chore: bump sgl-kernel v0.1.6.post1 (sgl-project#6955)
* chore: upgrade sgl-kernel v0.1.6.post1 (sgl-project#6957)
* [DeepseekR1-FP4] Add Support for nvidia/DeepSeekR1-FP4 model (sgl-project#6853)
* Revert "Fuse routed scaling factor in topk_reduce kernel (sgl-project#6220)" (sgl-project#6968)
* [AMD] Add more tests to per-commit-amd (sgl-project#6926)
* chore: bump sgl-kernel v0.1.7 (sgl-project#6963)
* Slightly improve the sampler to skip unnecessary steps (sgl-project#6956)
* rebase h20 fused_moe config (sgl-project#6966)
* Fix CI and triton moe Configs (sgl-project#6974)
* Remove unnecessary kernels of num_token_non_padded (sgl-project#6965)
* Extend cuda graph capture bs for B200 (sgl-project#6937)
* Fuse routed scaling factor in deepseek (sgl-project#6970)
* Sync cuda graph runners (sgl-project#6976)
* Fix draft extend ut stability with flush cache (sgl-project#6979)
* Fix triton sliding window test case (sgl-project#6981)
* Fix expert distribution dumping causes OOM (sgl-project#6967)
* Minor remove one kernel for DeepSeek (sgl-project#6977)
* [perf][sgl-kernel] extend cutlass_mla_decode to support num_head < 128 (sgl-project#6929)
* Enable more unit tests for AMD CI. (sgl-project#6983)
* Use torch.compile to fuse flash attention decode metadata preparation (sgl-project#6973)
* Eliminate stream sync to speed up LoRA batch init  (sgl-project#6960)
* support qwen3 emebedding (sgl-project#6990)
* Fix torch profiler bugs for bench_offline_throughput.py (sgl-project#6557)
* chore: upgrade flashinfer v0.2.6.post1 jit (sgl-project#6958)
* cleanup tmp dir (sgl-project#7007)
* chore: update pr test xeon (sgl-project#7008)
* Fix cutlass MLA gets almost zero accuracy (sgl-project#6998)
* Update amd nightly models CI. (sgl-project#6992)
* feat: add direct routing strategy to DP worker (sgl-project#6884)
* Fallback to lower triton version for unfound fused moe configs (sgl-project#7013)
* Fix torchvision version for Blackwell (sgl-project#7015)
* Simplify prepare_extend_after_decode (sgl-project#6987)
* Migrate to assertEqual (sgl-project#6741)
* Fix torch version in blackwell dockerfile (sgl-project#7017)
* chore: update pr test xeon (sgl-project#7018)
* Update default settings for blackwell (sgl-project#7023)
* Support both approximate and exact expert distribution collection (sgl-project#6964)
* Add decode req pool (sgl-project#6980)
* [theta]merge 0610
* [theta]merge 0610
* [CI] Add CI workflow for sgl-router docker build (sgl-project#7027)
* Fix fused_moe triton configs (sgl-project#7029)
* CPU: map changes from developing branch in sgl-kernel (sgl-project#6833)
* chore: bump v0.4.7 (sgl-project#7038)
* Update README.md (sgl-project#7040)
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