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/*
* Copyright (c) Meta Platforms, Inc. and affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/
#include <omp.h>
#include <unistd.h>
#include <memory>
#include <faiss/IVFlib.h>
#include <faiss/IndexIVF.h>
#include <faiss/impl/IDSelector.h>
#include <faiss/index_factory.h>
#include <faiss/index_io.h>
#include <faiss/utils/random.h>
#include <faiss/utils/utils.h>
/************************
* This benchmark attempts to measure the runtime overhead to use an IDSelector
* over doing an unconditional sequential scan. Unfortunately the results of the
* benchmark also depend a lot on the parallel_mode and the way
* search_with_parameters works.
*/
int main() {
using idx_t = faiss::idx_t;
int d = 64;
size_t nb = 1024 * 1024;
size_t nq = 512 * 16;
size_t k = 10;
std::vector<float> data((nb + nq) * d);
float* xb = data.data();
float* xq = data.data() + nb * d;
faiss::rand_smooth_vectors(nb + nq, d, data.data(), 1234);
std::unique_ptr<faiss::Index> index;
// const char *index_key = "IVF1024,Flat";
const char* index_key = "IVF1024,SQ8";
printf("index_key=%s\n", index_key);
std::string stored_name =
std::string("/tmp/bench_ivf_selector_") + index_key + ".faissindex";
if (access(stored_name.c_str(), F_OK) != 0) {
printf("creating index\n");
index.reset(faiss::index_factory(d, index_key));
double t0 = faiss::getmillisecs();
index->train(nb, xb);
double t1 = faiss::getmillisecs();
index->add(nb, xb);
double t2 = faiss::getmillisecs();
printf("Write %s\n", stored_name.c_str());
faiss::write_index(index.get(), stored_name.c_str());
} else {
printf("Read %s\n", stored_name.c_str());
index.reset(faiss::read_index(stored_name.c_str()));
}
faiss::IndexIVF* index_ivf = static_cast<faiss::IndexIVF*>(index.get());
index->verbose = true;
for (int tt = 0; tt < 3; tt++) {
if (tt == 1) {
index_ivf->parallel_mode = 3;
} else {
index_ivf->parallel_mode = 0;
}
if (tt == 2) {
printf("set single thread\n");
omp_set_num_threads(1);
}
printf("parallel_mode=%d\n", index_ivf->parallel_mode);
std::vector<float> D1(nq * k);
std::vector<idx_t> I1(nq * k);
{
double t2 = faiss::getmillisecs();
index->search(nq, xq, k, D1.data(), I1.data());
double t3 = faiss::getmillisecs();
printf("search time, no selector: %.3f ms\n", t3 - t2);
}
std::vector<float> D2(nq * k);
std::vector<idx_t> I2(nq * k);
{
double t2 = faiss::getmillisecs();
faiss::IVFSearchParameters params;
faiss::ivflib::search_with_parameters(
index.get(), nq, xq, k, D2.data(), I2.data(), ¶ms);
double t3 = faiss::getmillisecs();
printf("search time with nullptr selector: %.3f ms\n", t3 - t2);
}
FAISS_THROW_IF_NOT(I1 == I2);
FAISS_THROW_IF_NOT(D1 == D2);
{
double t2 = faiss::getmillisecs();
faiss::IVFSearchParameters params;
faiss::IDSelectorAll sel;
params.sel = &sel;
faiss::ivflib::search_with_parameters(
index.get(), nq, xq, k, D2.data(), I2.data(), ¶ms);
double t3 = faiss::getmillisecs();
printf("search time with selector: %.3f ms\n", t3 - t2);
}
FAISS_THROW_IF_NOT(I1 == I2);
FAISS_THROW_IF_NOT(D1 == D2);
std::vector<float> D3(nq * k);
std::vector<idx_t> I3(nq * k);
{
int nt = omp_get_max_threads();
double t2 = faiss::getmillisecs();
faiss::IVFSearchParameters params;
#pragma omp parallel for if (nt > 1)
for (idx_t slice = 0; slice < nt; slice++) {
idx_t i0 = nq * slice / nt;
idx_t i1 = nq * (slice + 1) / nt;
if (i1 > i0) {
faiss::ivflib::search_with_parameters(
index.get(),
i1 - i0,
xq + i0 * d,
k,
D3.data() + i0 * k,
I3.data() + i0 * k,
¶ms);
}
}
double t3 = faiss::getmillisecs();
printf("search time with null selector + manual parallel: %.3f ms\n",
t3 - t2);
}
FAISS_THROW_IF_NOT(I1 == I3);
FAISS_THROW_IF_NOT(D1 == D3);
}
return 0;
}
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