Struct faiss::gpu::IVFPQSearchCagraConfig
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struct IVFPQSearchCagraConfig
Public Members
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uint32_t n_probes = 20
The number of clusters to search.
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cudaDataType_t lut_dtype = CUDA_R_32F
Data type of look up table to be created dynamically at search time.
Possible values: [CUDA_R_32F, CUDA_R_16F, CUDA_R_8U]
The use of low-precision types reduces the amount of shared memory required at search time, so fast shared memory kernels can be used even for datasets with large dimansionality. Note that the recall is slightly degraded when low-precision type is selected.
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cudaDataType_t internal_distance_dtype = CUDA_R_32F
Storage data type for distance/similarity computed at search time.
Possible values: [CUDA_R_16F, CUDA_R_32F]
If the performance limiter at search time is device memory access, selecting FP16 will improve performance slightly.
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double preferred_shmem_carveout = 1.0
Preferred fraction of SM’s unified memory / L1 cache to be used as shared memory.
Possible values: [0.0 - 1.0] as a fraction of the
sharedMemPerMultiprocessor.One wants to increase the carveout to make sure a good GPU occupancy for the main search kernel, but not to keep it too high to leave some memory to be used as L1 cache. Note, this value is interpreted only as a hint. Moreover, a GPU usually allows only a fixed set of cache configurations, so the provided value is rounded up to the nearest configuration. Refer to the NVIDIA tuning guide for the target GPU architecture.
Note, this is a low-level tuning parameter that can have drastic negative effects on the search performance if tweaked incorrectly.
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uint32_t n_probes = 20