auto-enable lora kernels where possible (#2589)

* auto-enable lora kernels where possible

* test

* revert change to example yaml

* naming

* remove print

* slight logic change

src/axolotl/utils/schemas/config.py

@@ -1315,6 +1315,54 @@ class AxolotlConfigWCapabilities(AxolotlInputConfig):
                     )
         return data
 
+    @model_validator(mode="before")
+    @classmethod
+    def check_auto_enable_lora_kernels(cls, data):
+        # Only proceed if using LoRA or QLoRA adapter
+        if data.get("adapter") in ["lora", "qlora"]:
+            # Skip if already set, using unsloth optimizations, or using 8-bit
+            unsloth_fields = ["unsloth_lora_mlp", "unsloth_lora_qkv", "unsloth_lora_o"]
+            kernel_fields = ["lora_mlp_kernel", "lora_qkv_kernel", "lora_o_kernel"]
+            if (
+                any(data.get(k) is not None for k in kernel_fields)
+                or any(data.get(k) for k in unsloth_fields)
+                or data.get("adapter") == "lora"
+                and data.get("load_in_8bit")
+            ):
+                return data
+
+            # Check multi-GPU compatibility
+            capabilities = data.get("capabilities")
+            is_multi_gpu = capabilities and capabilities.get("n_gpu", 0) > 1
+            is_fsdp = data.get("fsdp") is not None
+            is_fsdp2 = (
+                data.get("fsdp_config") is not None
+                and str(data.get("fsdp_config").get("fsdp_version")) == "2"
+            )
+
+            if (
+                not is_multi_gpu
+                or (is_multi_gpu and not is_fsdp)
+                or (is_multi_gpu and is_fsdp2)
+            ):
+                # Auto-enable kernels if not explicitly set by user
+                if data.get("lora_mlp_kernel") is None:
+                    data["lora_mlp_kernel"] = True
+
+                if data.get("lora_qkv_kernel") is None:
+                    data["lora_qkv_kernel"] = True
+
+                if data.get("lora_o_kernel") is None:
+                    data["lora_o_kernel"] = True
+
+                LOG.warning(
+                    "Auto-enabling LoRA kernel optimizations for faster training. "
+                    + "Please explicitly set `lora_*_kernel` config values to `false` to disable. "
+                    + "See https://docs.axolotl.ai/docs/lora_optims.html for more info."
+                )
+
+        return data
+
     @model_validator(mode="before")
     @classmethod
     def check_adopt_torch_version(cls, data):

tests/e2e/patched/lora_kernels/test_lora_kernel_patching.py

@@ -2,8 +2,11 @@
 
 # pylint: disable=redefined-outer-name
 
+from pathlib import Path
+
 import pytest
 import torch
+import yaml
 from accelerate.state import PartialState
 from peft import PeftModelForCausalLM, get_peft_config
 from transformers import AutoModelForCausalLM, LlamaForCausalLM
@@ -11,6 +14,7 @@ from transformers.models.llama.configuration_llama import LlamaConfig
 from transformers.models.llama.modeling_llama import LlamaAttention
 from transformers.models.qwen3_moe.modeling_qwen3_moe import Qwen3MoeAttention
 
+from axolotl.cli.config import load_cfg
 from axolotl.kernels.lora import (
     apply_lora_mlp_geglu,
     apply_lora_mlp_swiglu,
@@ -421,3 +425,42 @@ def test_kernel_training_integration():
     # Verify correct activation function
     layer = model.model.model.layers[0]
     assert layer.mlp.forward.__func__ is apply_lora_mlp_swiglu
+
+
+def test_kernel_training_integration_auto_enable(temp_dir):
+    """Test model loading with auto-enabled kernel patches."""
+    # Create minimal config without explicitly setting kernel options
+    cfg = DictDefault(
+        {
+            "base_model": "HuggingFaceTB/SmolLM2-135M",
+            "tokenizer_config": "HuggingFaceTB/SmolLM2-135M",
+            "learning_rate": 0.000001,
+            "datasets": [
+                {
+                    "path": "mhenrichsen/alpaca_2k_test",
+                    "type": "alpaca",
+                }
+            ],
+            "micro_batch_size": 1,
+            "gradient_accumulation_steps": 1,
+            "adapter": "lora",
+            "lora_r": 8,
+            "lora_alpha": 16,
+            "lora_dropout": 0.0,
+            "lora_target_linear": True,
+            "sequence_len": 1024,
+        }
+    )
+
+    # Write cfg to yaml file
+    path = Path(temp_dir) / "config.yaml"
+    with open(path, "w", encoding="utf-8") as fout:
+        fout.write(yaml.dump(cfg.to_dict(), Dumper=yaml.Dumper))
+
+    # Load config
+    cfg = load_cfg(str(path))
+
+    # Verify kernel options were auto-enabled in the config
+    assert cfg.lora_mlp_kernel is True
+    assert cfg.lora_qkv_kernel is True
+    assert cfg.lora_o_kernel is True