Running on GPUs

hhhhfaiss

• Author：李英民 | Henry
• E-mail: li_yingmin@outlookdotcom
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接口

faiss::gpu::StandardGpuResources res;  // use a single GPU,开启GPU资源
faiss::gpu::GpuIndexFlatL2 gpu_index_flat(&res, d);//GPU index对象
gpu_index_flat.add(nb, xb);  // add vectors to the index
gpu_index_flat.search(nq, xq, k, D, I);

多重GPU

 int ngpus = faiss::gpu::getNumDevices();
    printf("Number of GPUs: %d\n", ngpus);
    std::vector<faiss::gpu::GpuResources*> res;
    std::vector<int> devs;
    for(int i = 0; i < ngpus; i++) {
        res.push_back(new faiss::gpu::StandardGpuResources);
        devs.push_back(i);
    }
    faiss::IndexFlatL2 cpu_index(d);
    faiss::Index *gpu_index =
        faiss::gpu::index_cpu_to_gpu_multiple(
            res,
            devs,
            &cpu_index
        );
    printf("is_trained = %s\n", gpu_index->is_trained ? "true" : "false");
    gpu_index->add(nb, xb);  // vectors to the index
    printf("ntotal = %ld\n", gpu_index->ntotal);
    int k = 4;
    {       // search xq
        long *I = new long[k * nq];
        float *D = new float[k * nq];
        gpu_index->search(nq, xq, k, D, I);
        // print results
        printf("I (5 first results)=\n");
        for(int i = 0; i < 5; i++) {
            for(int j = 0; j < k; j++)
                printf("%5ld ", I[i * k + j]);
            printf("\n");
        }
        printf("I (5 last results)=\n");
        for(int i = nq - 5; i < nq; i++) {
            for(int j = 0; j < k; j++)
                printf("%5ld ", I[i * k + j]);
            printf("\n");
        }
        delete [] I;
        delete [] D;
    }
    delete gpu_index;
    for(int i = 0; i < ngpus; i++) {
        delete res[i];
    }