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5-Multiple-GPUs.cpp
/**
* Copyright (c) 2015-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD+Patents license found in the
* LICENSE file in the root directory of this source tree.
*/
#include <cstdio>
#include <cstdlib>
#include <faiss/IndexFlat.h>
#include <faiss/gpu/GpuAutoTune.h>
#include <faiss/gpu/GpuIndexFlat.h>
#include <faiss/gpu/StandardGpuResources.h>
#include <faiss/gpu/utils/DeviceUtils.h>
int main() {
int d = 64; // dimension
int nb = 100000; // database size
int nq = 10000; // nb of queries
float *xb = new float[d * nb];
float *xq = new float[d * nq];
for(int i = 0; i < nb; i++) {
for(int j = 0; j < d; j++)
xb[d * i + j] = drand48();
xb[d * i] += i / 1000.;
}
for(int i = 0; i < nq; i++) {
for(int j = 0; j < d; j++)
xq[d * i + j] = drand48();
xq[d * i] += i / 1000.;
}
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); // add 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];
}
delete [] xb;
delete [] xq;
return 0;
}
faiss::IndexFlatL2
Definition: IndexFlat.h:79
faiss::Index::add
virtual void add(idx_t n, const float *x)=0
faiss::gpu::StandardGpuResources
Definition: StandardGpuResources.h:23
faiss::Index::ntotal
idx_t ntotal
total nb of indexed vectors
Definition: Index.h:65
faiss::Index::search
virtual void search(idx_t n, const float *x, idx_t k, float *distances, idx_t *labels) const =0
faiss::Index
Definition: Index.h:60
faiss::Index::is_trained
bool is_trained
set if the Index does not require training, or if training is done already
Definition: Index.h:69