https://github.com/codeplaysoftware/portfft
portFFT is a library implementing Fast Fourier Transforms using SYCL
https://github.com/codeplaysoftware/portfft
Last synced: 10 months ago
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portFFT is a library implementing Fast Fourier Transforms using SYCL
- Host: GitHub
- URL: https://github.com/codeplaysoftware/portfft
- Owner: codeplaysoftware
- License: apache-2.0
- Created: 2023-03-16T16:37:34.000Z (almost 3 years ago)
- Default Branch: main
- Last Pushed: 2024-09-09T12:49:53.000Z (over 1 year ago)
- Last Synced: 2024-09-09T15:26:39.508Z (over 1 year ago)
- Language: C++
- Homepage:
- Size: 1.79 MB
- Stars: 14
- Watchers: 20
- Forks: 6
- Open Issues: 3
-
Metadata Files:
- Readme: README.md
- Contributing: CONTRIBUTING
- License: LICENSE
- Code of conduct: CODE_OF_CONDUCT.md
- Security: SECURITY.md
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README
# portFFT
[](https://scorecard.dev/viewer/?uri=github.com/codeplaysoftware/portFFT)
## Introduction
portFFT is a library implementing Fast Fourier Transforms using SYCL and C++.
portFFT is in early stages of development and will support more options and optimizations in the future.
## Pre-requisites
* [DPC++] oneAPI release 2024.0
* Nightly releases from [intel/llvm] should work but are not tested
* Other SYCL implementations are not tested
* [Level Zero] drivers
* OpenCL drivers are not supported
* CMake 3.20+
* For tests and verifying benchmarks:
* Python
* Numpy
## Getting Started
### Building with CMake
Clone portFFT and run the following commands from the cloned repository.
Build using DPC++ 2024.0 as:
```shell
source /path/to/intel/oneapi/compiler/2024.0/env/vars.sh
cmake -Bbuild -DCMAKE_CXX_COMPILER=icpx -DPORTFFT_BUILD_TESTS=ON -DPORTFFT_BUILD_BENCHMARKS=ON
cmake --build build
```
Build using DPC++ nightlies as (SPIR64 target only):
```shell
cmake -Bbuild -DCMAKE_CXX_COMPILER=/path/to/dpcpp/bin/clang++ -DCMAKE_C_COMPILER=/path/to/dpcpp/bin/clang -DPORTFFT_BUILD_TESTS=ON -DPORTFFT_BUILD_BENCHMARKS=ON
cmake --build build
```
To compile AOT for a specific device, specify the target device with:
```shell
-DPORTFFT_DEVICE_TRIPLE=[T1,..,Tn]
```
The list of available targets can be found on [DPC++ compiler documentation page].
Some AOT targets do not support double precision.
To disable the building of tests and benchmarks using double precision, set `-DPORTFFT_ENABLE_DOUBLE_BUILDS=OFF`.
portFFT currently requires to set the subgroup size at compile time. Multiple sizes can be set and the first one that is supported by the device will be used. Depending on the device used you may need to set the subgroup size with `-DPORTFFT_SUBGROUP_SIZES=`. By default only size 32 is used.
If you run into the exception with the message `None of the compiled subgroup sizes are supported by the device!` then `DPORTFFT_SUBGROUP_SIZES` must be set to a different value(s) supported by the device.
### Tests
Tests are build if the CMake setting `PORTFFT_BUILD_TESTS` is set to `ON`.
Additionally, this enables `clang-tidy` checks if `PORTFFT_CLANG_TIDY` is at its default value of `ON`.
Automatic fixing of some `clang-tidy` warnings can be enabled by setting `PORTFFT_CLANG_TIDY_AUTOFIX` to `ON`.
Run the tests from the build folder with:
```shell
ctest
```
### portFFT benchmarks
Run pre-defined benchmarks from the build folder with:
```shell
./test/bench/bench_float
```
Run manual benchmarks from the build folder with for instance:
```shell
./test/bench/bench_manual_float d=cpx,n=5
```
Use the `--help` flag to print help message on the configuration syntax.
## Supported configurations
portFFT is still in early development. The supported configurations are:
* complex-to-complex transforms
* interleaved complex and split complex (restricted to one dimension) storage
* single and double precisions
* forward and backward directions
* in-place and out-of-place transforms
* USM and buffer containers
* batched transforms
* 1D transforms
* multi-dimensional transforms with the following restrictions:
* default values for strides and distances
* size in each dimension must be supported by 1D transforms
* Arbitrary forward and backward scales
* Arbitrary forward and backward offsets
* Arbitrary strides and distance where the problem size + auxilary data fits in the registers of a single subgroup.
Any 1D arbitrarily large input size that fits in global memory is supported, with a restriction that large input sizes should not have large prime factors.
The largest prime factor depend on the device and the values set by `PORTFFT_REGISTERS_PER_WI` and `PORTFFT_SUBGROUP_SIZES`.
For instance with `PORTFFT_REGISTERS_PER_WI` set to `128` (resp. `256`) each work-item can hold a maximum of 27 (resp. 56) complex values, thus with `PORTFFT_SUBGROUP_SIZES` set to `32` the largest prime factor cannot exceed `27*32=864` (resp. `56*32=1792`).
portFFT may allocate up to `2 * PORTFFT_MAX_CONCURRENT_KERNELS * input_size` scratch memory, depending on the configuration passed.
Any batch size is supported as long as the input and output data fits in global memory.
By default the library assumes subgroup size of 32 is used. If that is not supported by the device it is running on, the subgroup size can be set using `PORTFFT_SUBGROUP_SIZES`.
Configurations that attempt to read from the same memory address from two separate batches of a transform are not supported.
## Known issues
* portFFT relies on SYCL specialization constants which have some limitations currently:
* Some optimizations seem to be missing at JIT compile time. We are working to improve this.
* Specialization constants are currently emulated on Nvidia and AMD backends which prevents some optimizations.
Overall the work of optimizing portFFT is still in progress.
## Troubleshooting
The library should compile without error on our supported platforms.
If you run into trouble, or think you have found a bug, we have a support
forum available through the [developer website], or create an issue on GitHub.
## Maintainers
This library is maintained by [Codeplay Software Ltd].
If you have any problems, please contact sycl@codeplay.com.
## Contributions
This library is licensed under the Apache 2.0 license. Patches are very
welcome! If you have an idea for a new feature or a fix, please get in
contact.
[DPC++]: https://www.intel.com/content/www/us/en/develop/documentation/oneapi-dpcpp-cpp-compiler-dev-guide-and-reference/top.html
[intel/llvm]: https://github.com/intel/llvm/releases
[Level Zero]: https://www.intel.com/content/www/us/en/docs/dpcpp-cpp-compiler/developer-guide-reference/2025-0/intel-oneapi-level-zero-switch.html
[developer website]: https://developer.codeplay.com
[Codeplay Software Ltd]: https://www.codeplay.com
[DPC++ compiler documentation page]: https://intel.github.io/llvm-docs/UsersManual.html