[TRTLLM-6826][feat] Allow sending more than 2GiB through MPI by using mpi4py.util.pkl5

[amitz-nv]

Summary by CodeRabbit

• Changes
  • Updated the underlying MPI communicator to improve data transmission capabilities, supporting larger message sizes.

Description

Use pickle protocol 5 in MPI, which allows sending more than 2GiB in a single call. This limit is sometimes reached when using LoRA, as the when a LoRA adapter is requested and it's not in the LoRA CPU cache, its weights are attached to the request.

For more details on MPI pickle protocol 5, see: https://mpi4py.readthedocs.io/en/stable/mpi4py.util.pkl5.html

Benchmark

The changes in this PR seem to have no negative performance impact on the following benchmark:
trtllm-bench --model Llama-3.1-8B-Instruct-FP8 throughput --dataset synthetic_lora_data_2048.json --backend pytorch --extra_llm_api_options extra-llm-api-options.yaml --num_requests 1024 --concurrency 32 with a single lora adapter (Llama-3-Chinese-8B-Instruct-v2-LoRA).

extra-llm-api-options.yaml contains:

lora_config:
  lora_dir:
    - /workspaces/tensorrt_llm/loras/0
  max_lora_rank: 64
  max_loras: 8
  max_cpu_loras: 8
  lora_target_modules:
    - attn_q
    - attn_k
    - attn_v
  trtllm_modules_to_hf_modules:
    attn_q: q_proj
    attn_k: k_proj
    attn_v: v_proj

The synthetic dataset was generated with:

python3 /workspaces/tensorrt_llm/benchmarks/cpp/prepare_dataset.py --stdout --task-id 0 --tokenizer=/home/scratch.trt_llm_data/llm-models/llama-3.1-model/Llama-3.1-8B-Instruct-FP8 --lora-dir=/workspaces/tensorrt_llm/loras token-norm-dist --num-requests=2048 --input-mean=128 --output-mean=128 --input-stdev=16 --output-stdev=24 > /workspaces/tensorrt_llm/synthetic_lora_data_2048.json

Test Coverage

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[coderabbitai]

📝 Walkthrough

Walkthrough

The global MPI communicator variable comm in tensorrt_llm/_utils.py has been changed from using MPI.COMM_WORLD directly to wrapping it with pkl5.Intracomm from mpi4py.util. This alters the communicator's type but does not modify any other logic or control flow in the module.

Changes

Cohort / File(s)	Change Summary
MPI Communicator Wrapping tensorrt_llm/_utils.py	Imports pkl5 from mpi4py.util and changes global comm from MPI.COMM_WORLD to pkl5.Intracomm(MPI.COMM_WORLD).

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

Suggested reviewers

• pcastonguay
• chuangz0

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[amitz-nv]

/bot run

[tensorrt-cicd]

PR_Github #13983 [ run ] triggered by Bot

[tensorrt-cicd]

PR_Github #13983 [ run ] completed with state FAILURE
/LLM/main/L0_MergeRequest_PR pipeline #10534 completed with status: 'FAILURE'

[amitz-nv]

/bot run --disable-fail-fast

[tensorrt-cicd]

PR_Github #13987 [ run ] triggered by Bot

[tensorrt-cicd]

PR_Github #13987 [ run ] completed with state FAILURE
/LLM/main/L0_MergeRequest_PR pipeline #10538 completed with status: 'FAILURE'

[amitz-nv]

/bot run --disable-fail-fast

[tensorrt-cicd]

PR_Github #13999 [ run ] triggered by Bot

[amitz-nv]

/bot run

[tensorrt-cicd]

PR_Github #14012 [ run ] triggered by Bot

[tensorrt-cicd]

PR_Github #13999 [ run ] completed with state ABORTED

[tensorrt-cicd]

PR_Github #14012 [ run ] completed with state SUCCESS
/LLM/main/L0_MergeRequest_PR pipeline #10561 completed with status: 'SUCCESS'

[Wanli-Jiang]

Tested with phi4-mm lora, and can solve the issue, thanks for your help!

[shaharmor98]

LGTM