This PR clarifies which features are supported on P100 via its tests,
though Pascal is not officially and fully supported by Triton.
## What this PR does
- Skip unsupported tests on P100.
- Atomic RMW
- `tl.dot()` (perhaps not all patterns, but basically most `tl.dot()`
tests do not work on P100).
- Add an explicit error if shared memory size >= 64K on P100.
- Otherwise it causes `Invalid CUDA argument` error at
`cuLaunchKernel()`, but this error is not very straightforward to
understand. Instead of this generic CUDA argument error, this PR makes
Triton show an error during codegen when `sm < 70`. This check happens
in C/C++ so won't add an overhead in Triton's Python runtime.
- 3 tests (see below) are currently failing, but these are not marked as
skipped because any codegen update in the future can change the kernel
size of the other tests.
- This change won't affect Triton-MLIR. Hopefully Triton-MLIR's generic
`tl.dot()` implementation would support P100.
Importantly, Triton passed all the other tests on P100. Though this
support is not official, it is great for, for example, PyTorch's
TorchDynamo/Inductor, which can use Triton (without `tl.dot()`) for its
backend (https://github.com/pytorch/torchdynamo/issues/1591).
### Results on P100 (Google Cloud)
```sh
$ pytest test/unit
...
================================================================================== short test summary info ==================================================================================
FAILED test/unit/language/test_core.py::test_reduce2d[argmin-float32-shape99-1] - RuntimeError: Device does not support shared memory of 65536bytes
FAILED test/unit/language/test_core.py::test_reduce2d[argmax-float32-shape113-1] - RuntimeError: Device does not support shared memory of 65536bytes
FAILED test/unit/language/test_core.py::test_permute[float32-shape5-perm5] - RuntimeError: Device does not support shared memory of 67584bytes
================================================================== 3 failed, 3824 passed, 952 skipped in 470.90s (0:07:50) ==================================================================
```
<details><summary> <b>Environment Details (collapsed)</b></summary>
<p>
### VM details (Google Cloud)
https://cloud.google.com/
```
# You need a paid account (free trial does not cover GPUs)
Google Cloud -> New Project -> Compute-Engine -> VM Instance
Machine:
GPU: NVIDIA Tesla P100 x 1
CPU: 2 vCPUs, 7.5GB memory
Boot disk:
OS: Ubuntu 18.04 LTS
Disk: 40GB (cannot build Triton on the default 10GB disk)
- When I tried, about $1.2 per hour.
- US instances were full when I tried. I used Asia or Australia.
- Needed a paid account (GPU is not covered by free trial)
- Needed quota request for any GPU instance (by default, no GPU instance is allowed). Needed to wait an hour for approval
```
### Reproducer
```sh
## 1. Install CUDA and a driver
# Update the apt key (https://developer.nvidia.com/blog/updating-the-cuda-linux-gpg-repository-key/)
sudo apt-key del 7fa2af80
wget https://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64/cuda-keyring_1.0-1_all.deb
# Download CUDA as instructed
wget https://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64/cuda-ubuntu1804.pin
sudo mv cuda-ubuntu1804.pin /etc/apt/preferences.d/cuda-repository-pin-600
sudo apt-key adv --fetch-keys https://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64/7fa2af80.pub
sudo add-apt-repository "deb https://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64/ /"
sudo apt-get update
sudo apt-get -y install cuda
# Are you using P100?
nvidia-smi | grep "Tesla P100"
## 2. Setup the build environment
sudo apt update
sudo apt install -y build-essential wget git libz-dev
wget https://repo.anaconda.com/archive/Anaconda3-2022.05-Linux-x86_64.sh
bash Anaconda3-2022.05-Linux-x86_64.sh -b -p $(pwd)/anaconda3
eval "$($(pwd)/anaconda3/bin/conda shell.bash hook)"
conda create -y --name triton_base
conda activate triton_base
conda install -y cmake setuptools
## 3. Build Triton
git clone https://github.com/openai/triton.git
cd triton/python
pip3 install -e '.[tests]'
## 4. Test
pytest test/unit
```
### Environment
```sh
$ nvidia-smi
+-----------------------------------------------------------------------------+
| NVIDIA-SMI 520.61.05 Driver Version: 520.61.05 CUDA Version: 11.8 |
|-------------------------------+----------------------+----------------------+
| GPU Name Persistence-M| Bus-Id Disp.A | Volatile Uncorr. ECC |
| Fan Temp Perf Pwr:Usage/Cap| Memory-Usage | GPU-Util Compute M. |
| | | MIG M. |
|===============================+======================+======================|
| 0 Tesla P100-PCIE... On | 00000000:00:04.0 Off | 0 |
| N/A 36C P0 25W / 250W | 0MiB / 16384MiB | 0% Default |
| | | N/A |
+-------------------------------+----------------------+----------------------+
```
</p></details>
This PR completely rewrites the runtime of Triton to be more lean and
clearly separate the compilation step from the just-in-time caching logic.
This should substantially reduce launch overhead.
* dds layout now internally re-uses dsd code path for increased code
* at_mask and kp_mask related things are now dropped from the softmax API. I couldn't think of any case where it was needed beyond is_causal. And if there is any, we should probably find a way to get it implemented statically so that users don't have to materialize masks.
* fixed bug in blocksparse matmul that caused troubles when layout had a full row/col of zeros
* blocksparse softmax now no longer modifies any data in-place
* blocksparse softmax now takes an is_dense arguments that provides better performance. Passing is_dense=True, is_causal=True is the best way to achieve triangular attention.
* unit tests now test backward pass
Run:
```
isort ./python
autopep8 -i --ignore E501,E701,E731 $(find ./python/ -name '*.py')
```
with an `.isort.cfg` and then clean up a few warts. This PR should be a no-op; the idea is that this is all boring whitespace changes, and any config file changes will be in a different change to make it easier to review.
