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Docs #268

Merged
merged 16 commits into from
Sep 12, 2023
182 changes: 12 additions & 170 deletions README.md
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# KvikIO: C++ and Python bindings to cuFile
# KvikIO: High Performance File IO

## Summary

This provides C++ and Python bindings to cuFile, which enables GPUDirect Storage (GDS).
KvikIO also works efficiently when GDS isn't available and can read/write both host and
device data seamlessly.
KvikIO is a Python and C++ library for high performance file IO. It provides C++ and Python
bindings to [cuFile](https://docs.nvidia.com/gpudirect-storage/api-reference-guide/index.html),
which enables [GPUDirect Storage (GDS)](https://developer.nvidia.com/blog/gpudirect-storage/).
KvikIO also works efficiently when GDS isn't available and can read/write both host and device data seamlessly.
The C++ library is header-only making it easy to include in [existing projects](https://github.com/rapidsai/kvikio/blob/HEAD/cpp/examples/downstream/).


### Features

* Object Oriented API.
* Exception handling.
* Object oriented API of [cuFile](https://docs.nvidia.com/gpudirect-storage/api-reference-guide/index.html) with C++/Python exception handling.
* A Python [Zarr](https://zarr.readthedocs.io/en/stable/) backend for reading and writing GPU data to file seamlessly.
* Concurrent reads and writes using an internal thread pool.
* Non-blocking API.
* Python Zarr reader.
* Handle both host and device IO seamlessly.
* Provides Python bindings to [nvCOMP](https://github.com/NVIDIA/nvcomp).

## Requirements

To install users should have a working Linux machine with CUDA Toolkit
installed (v11.4+) and a working compiler toolchain (C++17 and cmake).

### C++

The C++ bindings are header-only and depends on the CUDA Driver API.
In order to build and run the example code, CMake and the CUDA Runtime
API is required.

### Python

The Python package depends on the following packages:

* cython
* pip
* setuptools
* scikit-build

For nvCOMP, benchmarks, examples, and tests:

* pytest
* numpy
* cupy

## Install

### Conda

Install the stable release from the `rapidsai` channel like:

```
conda create -n kvikio_env -c rapidsai -c conda-forge kvikio
```

Install the `kvikio` conda package from the `rapidsai-nightly` channel like:

```
conda create -n kvikio_env -c rapidsai-nightly -c conda-forge python=3.10 cuda-version=11.8 kvikio
```

If the nightly install doesn't work, set `channel_priority: flexible` in your `.condarc`.

In order to setup a development environment run:
```
conda env create --name kvikio-dev --file conda/environments/all_cuda-118_arch-x86_64.yaml
```

### C++ (build from source)

To build the C++ example run:

```
./build.sh libkvikio
```

Then run the example:

```
./examples/basic_io
```

### Python (build from source)

To build and install the extension run:

```
./build.sh kvikio
```

One might have to define `CUDA_HOME` to the path to the CUDA installation.

In order to test the installation, run the following:

```
pytest tests/
```

And to test performance, run the following:

```
python benchmarks/single-node-io.py
```

## Examples


### Notebooks
- [How to read and write GPU memory directly to/from Zarr files](notebooks/zarr.ipynb)


### C++

```c++
#include <cstddef>
#include <cuda_runtime.h>
#include <kvikio/file_handle.hpp>
using namespace std;

int main()
{
// Create two arrays `a` and `b`
constexpr std::size_t size = 100;
void *a = nullptr;
void *b = nullptr;
cudaMalloc(&a, size);
cudaMalloc(&b, size);

// Write `a` to file
kvikio::FileHandle fw("test-file", "w");
size_t written = fw.write(a, size);
fw.close();

// Read file into `b`
kvikio::FileHandle fr("test-file", "r");
size_t read = fr.read(b, size);
fr.close();

// Read file into `b` in parallel using 16 threads
kvikio::default_thread_pool::reset(16);
{
kvikio::FileHandle f("test-file", "r");
future<size_t> future = f.pread(b_dev, sizeof(a), 0); // Non-blocking
size_t read = future.get(); // Blocking
// Notice, `f` closes automatically on destruction.
}
}
```

### Python

```python
import cupy
import kvikio

a = cupy.arange(100)
f = kvikio.CuFile("test-file", "w")
# Write whole array to file
f.write(a)
f.close()

b = cupy.empty_like(a)
f = kvikio.CuFile("test-file", "r")
# Read whole array from file
f.read(b)
assert all(a == b)

# Use contexmanager
c = cupy.empty_like(a)
with kvikio.CuFile(path, "r") as f:
f.read(c)
assert all(a == c)

# Non-blocking read
d = cupy.empty_like(a)
with kvikio.CuFile(path, "r") as f:
future1 = f.pread(d[:50])
future2 = f.pread(d[50:], file_offset=d[:50].nbytes)
future1.get() # Wait for first read
future2.get() # Wait for second read
assert all(a == d)
```
### Documentation
* Python: <https://docs.rapids.ai/api/kvikio/nightly/>
* C++: <https://docs.rapids.ai/api/libkvikio/nightly/>
4 changes: 3 additions & 1 deletion conda/environments/all_cuda-118_arch-x86_64.yaml
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Expand Up @@ -23,16 +23,18 @@ dependencies:
- libcufile=1.4.0.31
- ninja
- numpy>=1.21
- numpydoc
- nvcc_linux-64=11.8
- nvcomp==2.6.1
- packaging
- pre-commit
- pydata-sphinx-theme
- pytest
- pytest-cov
- python>=3.9,<3.11
- scikit-build>=0.13.1
- sphinx
- sphinx-click
- sphinx_rtd_theme
- sysroot_linux-64=2.17
- zarr
name: all_cuda-118_arch-x86_64
4 changes: 3 additions & 1 deletion conda/environments/all_cuda-120_arch-x86_64.yaml
Original file line number Diff line number Diff line change
Expand Up @@ -23,15 +23,17 @@ dependencies:
- libcufile-dev
- ninja
- numpy>=1.21
- numpydoc
- nvcomp==2.6.1
- packaging
- pre-commit
- pydata-sphinx-theme
- pytest
- pytest-cov
- python>=3.9,<3.11
- scikit-build>=0.13.1
- sphinx
- sphinx-click
- sphinx_rtd_theme
- sysroot_linux-64=2.17
- zarr
name: all_cuda-120_arch-x86_64
118 changes: 115 additions & 3 deletions cpp/doxygen/main_page.md
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@@ -1,4 +1,116 @@
# libkvikio
# Welcome to KvikIO's C++ documentation!

libkvikio is a C++ header-only library providing bindings to
cuFile, which enables GPUDirectStorage (GDS).
KvikIO is a Python and C++ library for high performance file IO. It provides C++ and Python
bindings to [cuFile](https://docs.nvidia.com/gpudirect-storage/api-reference-guide/index.html)
which enables [GPUDirect Storage (GDS)](https://developer.nvidia.com/blog/gpudirect-storage/).
KvikIO also works efficiently when GDS isn't available and can read/write both host and device data seamlessly.

KvikIO C++ is a header-only library that is part of the [RAPIDS](https://rapids.ai/) suite of open-source software libraries for GPU-accelerated data science.

---
**Notice** this is the documentation for the C++ library. For the Python documentation of KvikIO, see under **KvikIO**.

---

## Features

* Object Oriented API.
* Exception handling.
* Concurrent reads and writes using an internal thread pool.
* Non-blocking API.
* Handle both host and device IO seamlessly.

## Installation

KvikIO is a header-only library and as such doesn't need installation.
However, for convenience we release Conda packages that makes it easy
to include KvikIO in your CMake projects.

### Conda/Mamba

We strongly recommend using `mamba <https://github.com/mamba-org/mamba>`_ inplace of conda, which we will do throughout the documentation.

Install the **stable release** from the ``rapidsai`` channel with the following:
```sh
# Install in existing environment
mamba install -c rapidsai -c conda-forge libkvikio
# Create new environment (CUDA 11.8)
mamba create -n libkvikio-env -c rapidsai -c conda-forge cuda-version=11.8 libkvikio
# Create new environment (CUDA 12.0)
mamba create -n libkvikio-env -c rapidsai -c conda-forge cuda-version=12.0 libkvikio
```

Install the **nightly release** from the ``rapidsai-nightly`` channel with the following:

```sh
# Install in existing environment
mamba install -c rapidsai-nightly -c conda-forge libkvikio
# Create new environment (CUDA 11.8)
mamba create -n libkvikio-env -c rapidsai-nightly -c conda-forge python=3.10 cuda-version=11.8 libkvikio
# Create new environment (CUDA 12.0)
mamba create -n libkvikio-env -c rapidsai-nightly -c conda-forge python=3.10 cuda-version=12.0 libkvikio
```

---
**Notice** if the nightly install doesn't work, set ``channel_priority: flexible`` in your ``.condarc``.

---

### Include KvikIO in a CMake project
An example of how to include KvikIO in an existing CMake project can be found here: <https://github.com/rapidsai/kvikio/blob/HEAD/cpp/examples/downstream/>.


### Build from source

To build the C++ example run:

```
./build.sh libkvikio
```

Then run the example:

```
./examples/basic_io
```


## Example

```cpp
#include <cstddef>
#include <cuda_runtime.h>
#include <kvikio/file_handle.hpp>
using namespace std;

int main()
{
// Create two arrays `a` and `b`
constexpr std::size_t size = 100;
void *a = nullptr;
void *b = nullptr;
cudaMalloc(&a, size);
cudaMalloc(&b, size);

// Write `a` to file
kvikio::FileHandle fw("test-file", "w");
size_t written = fw.write(a, size);
fw.close();

// Read file into `b`
kvikio::FileHandle fr("test-file", "r");
size_t read = fr.read(b, size);
fr.close();

// Read file into `b` in parallel using 16 threads
kvikio::default_thread_pool::reset(16);
{
kvikio::FileHandle f("test-file", "r");
future<size_t> future = f.pread(b_dev, sizeof(a), 0); // Non-blocking
size_t read = future.get(); // Blocking
// Notice, `f` closes automatically on destruction.
}
}
```

For a full runnable example see <https://github.com/rapidsai/kvikio/blob/HEAD/cpp/examples/basic_io.cpp>.
4 changes: 3 additions & 1 deletion dependencies.yaml
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Expand Up @@ -236,8 +236,10 @@ dependencies:
common:
- output_types: [conda, requirements]
packages:
- pydata-sphinx-theme
- numpydoc
- sphinx
- sphinx-click
- sphinx_rtd_theme
- output_types: conda
packages:
- doxygen=1.8.20 # pre-commit hook needs a specific version.
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1 change: 0 additions & 1 deletion docs/source/api.rst
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Expand Up @@ -18,7 +18,6 @@ Zarr
.. autoclass:: GDSStore
:members:


Defaults
--------
.. currentmodule:: kvikio.defaults
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