KvikIO (pronounced "kuh-VICK-eye-oh", see here for pronunciation of kvik) is a Python and C++ library for high performance file IO. It 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. The C++ library is header-only making it easy to include in existing projects.
- Object oriented API of cuFile with C++/Python exception handling.
- A Python Zarr backend for reading and writing GPU data to file seamlessly.
- Concurrent reads and writes using an internal thread pool.
- Non-blocking API.
- Transparently handles reads and writes to/from memory on both host and device.
- Provides Python bindings to nvCOMP.
- Python: https://docs.rapids.ai/api/kvikio/nightly/
- C++: https://docs.rapids.ai/api/libkvikio/nightly/
import cupy
import kvikio
def main(path):
a = cupy.arange(100)
f = kvikio.CuFile(path, "w")
# Write whole array to file
f.write(a)
f.close()
b = cupy.empty_like(a)
f = kvikio.CuFile(path, "r")
# Read whole array from file
f.read(b)
assert all(a == b)
f.close()
# 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)
# Note: must wait for futures before exiting block
# at which point the file is closed.
future1.get() # Wait for first read
future2.get() # Wait for second read
assert all(a == d)
if __name__ == "__main__":
main("/tmp/kvikio-hello-world-file")#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);
{
// FileHandles have RAII semantics
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.
}
}