[tutorial] updated auto parallel demo with latest data path (#1917)

examples/tutorial/auto_parallel/README.md

@@ -2,7 +2,8 @@
 
 ## Prepare Dataset
 
-We use CIFAR10 dataset in this example. The dataset will be downloaded to `./data` by default.
+We use CIFAR10 dataset in this example. You should invoke the `donwload_cifar10.py` in the tutorial root directory or directly run the `auto_parallel_with_resnet.py`.
+The dataset will be downloaded to `colossalai/examples/tutorials/data` by default.
 If you wish to use customized directory for the dataset. You can set the environment variable `DATA` via the following command.
 
 ```bash
@@ -13,7 +14,7 @@ export DATA=/path/to/data
 ## Run on 2*2 device mesh
 
 ```bash
-colossalai run --nproc_per_node 4 auto_parallel_demo.py
+colossalai run --nproc_per_node 4 auto_parallel_with_resnet.py
 ```
 
 ## Auto Checkpoint Benchmarking

examples/tutorial/auto_parallel/auto_parallel_with_resnet.py

@@ -24,7 +24,7 @@ from colossalai.logging import get_dist_logger
 from colossalai.nn.lr_scheduler import CosineAnnealingLR
 from colossalai.utils import get_dataloader
 
-DATA_ROOT = Path(os.environ.get('DATA', './data'))
+DATA_ROOT = Path(os.environ.get('DATA', '../data')).absolute()
 BATCH_SIZE = 1024
 NUM_EPOCHS = 10