New OOM errors for ThunderFX and FSDP

[mpatel31415]

🐛 Bug

Recently we got OOM errors causing failures of Gemma-2-2b (in canary runs) and distributed training of stablecode-completion-alpha-3b.

To Reproduce

Please use:
1 node(s), each with 8 GPUs.
Image "INTERNAL_IMAGE:pjnl-20241107"
Training script:

python /opt/pytorch/lightning-thunder/thunder/benchmarks/benchmark_litgpt.py \
    --model_name  Gemma-2-2b \
    --distributed_mode fsdp \
    --shard_mode zero2 \
    --compile dynamo_thunder \
    --checkpoint_activations False \
    --low_precision_mode none  \
    --micro_batch_size 1

Environment

system.device_product_name DGXH100
system.gpu_driver_version 535.129.03
libraries.cuda 12.6.98.001
libraries.pip.lightning 2.4.0.dev20240728
libraries.pip.lightning-thunder 0.2.0.dev0
libraries.pip.lightning-utilities 0.11.8
libraries.pip.litgpt 0.4.11
libraries.pip.nvfuser 0.2.22+gitba4f7d4
libraries.pip.pytorch-lightning 2.4.0
libraries.pip.torch 2.6.0a0+gita9b4989
libraries.pip.torchao 0.6.1
libraries.pip.torchmetrics 1.5.1
libraries.pip.torchvision 0.19.0a0+d23a6e1