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Release 13.4 of the CUDA Samples supported by CUDA Toolkit 13.4. See Changelog for more information.
87 lines
2.9 KiB
Markdown
87 lines
2.9 KiB
Markdown
# localityDomains - CUDA Runtime API Locality Domains
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## Description
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This CUDA Runtime API sample demonstrates localized compute and memory resources.
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Compute is localized by splitting a device's SM resources into locality domain partitions and constructing a green context and stream per locality domain. Memory is localized by allocating from localized memory pools.
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## What You'll Learn
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How to:
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- query a device's locality domain count and SM count per domain
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- partition SM resources by locality domain ID
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- create green contexts and streams from localized SM partitions
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- create localized memory pools and allocate from them asynchronously
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- query the locality domain associated with a stream and device pointer
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## Key Concepts
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- **Locality domain** — a portion of a GPU that contains streaming multiprocessors (SMs) and device memory.
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**Green context** — an execution context created from a selected subset of device resources.
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- **Localized memory pool** — a stream-ordered allocator whose physical memory is placed in a selected locality domain.
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## Key APIs
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### CUDA Runtime
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- `cudaDeviceGetAttribute` — query the number of locality domains and SMs per domain
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- `cudaDevSmResourceSplit` — partition the device's SM resources
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- `cudaMemPoolCreate` — create a localized memory pool and allocate from it
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- `cudaStreamGetDevResource` — inspect stream locality
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- `cudaPointerGetAttributes` — inspect allocation locality
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## Requirements
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### Hardware
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- NVIDIA GPU that supports locality domains and stream-ordered memory pools
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### Software
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- CUDA Toolkit and NVIDIA driver with locality domain support
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- Linux or QNX on x86_64 or aarch64
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- CMake 3.20 or newer
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- A C++17-capable host compiler
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## How to Build
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See the [top-level README](../../../README.md#building-cuda-samples) for full build instructions, including how to build all samples or a single sample standalone.
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## How to Run
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```bash
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./localityDomains
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```
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No command-line arguments are required. The sample always runs on device 0.
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## Expected Output
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The number of locality domains and SMs depends on the GPU. A run has the following form:
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```text
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CUDA Runtime API locality domains sample
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Locality domain count: <domain count>
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SMs per locality domain: <SM count>
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Device SMs split into <domain count> partitions
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- result[0]: .localityDomainId = 0, .smCount = <SM count>
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...
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Green context stream 0 is localized to locality domain 0
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...
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allocation 0x<address> is localized to locality domain 0
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...
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```
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If device 0 does not support memory pools, the sample reports that it is waiving execution and exits with status EXIT_WAIVED.
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## Files
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- `localityDomains.cu` — Runtime API example
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- `README.md` — this file
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- `CMakeLists.txt` — build configuration
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## See Also
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- [CUDA Runtime API](https://docs.nvidia.com/cuda/cuda-runtime-api/)
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- [CUDA Programming Guide](https://docs.nvidia.com/cuda/cuda-programming-guide/)
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