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bench_cppcontrib_sa_decode.cpp
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/**
* Copyright (c) Facebook, Inc. and its 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 <algorithm>
#include <chrono>
#include <iostream>
#include <memory>
#include <random>
#include <thread>
#include <tuple>
#include <vector>
#include <faiss/Index.h>
#include <faiss/Index2Layer.h>
#include <faiss/IndexIVFPQ.h>
#include <faiss/IndexPQ.h>
#include <faiss/impl/io.h>
#include <faiss/index_factory.h>
#include <faiss/index_io.h>
#include <faiss/IndexRowwiseMinMax.h>
#include <faiss/cppcontrib/SaDecodeKernels.h>
// train a dataset
std::tuple<std::shared_ptr<faiss::Index>, std::vector<uint8_t>> trainDataset(
const std::vector<float>& input,
const uint64_t n,
const uint64_t d,
const std::string& description) {
//
omp_set_num_threads(std::thread::hardware_concurrency());
// train an index
auto index = std::shared_ptr<faiss::Index>(
faiss::index_factory((int)d, description.c_str()));
index->train((int)n, input.data());
// encode
const size_t codeSize = index->sa_code_size();
std::vector<uint8_t> encodedData(n * codeSize);
index->sa_encode(n, input.data(), encodedData.data());
return std::make_tuple(std::move(index), std::move(encodedData));
}
// generate a dataset
std::vector<float> generate(const size_t n, const size_t d) {
std::vector<float> data(n * d);
std::minstd_rand rng(345);
std::uniform_real_distribution<float> ux(0, 1);
//
for (size_t k = 0; k < n; k++) {
for (size_t j = 0; j < d; j++) {
data[k * d + j] = ux(rng);
}
}
return data;
}
double getError(
const uint64_t n,
const uint64_t d,
const std::vector<float>& v1,
const std::vector<float>& v2) {
double error = 0;
for (uint64_t i = 0; i < n; i++) {
double localError = 0;
for (uint64_t j = 0; j < d; j++) {
double q = v1[i * d + j] - v2[i * d + j];
localError += q * q;
}
error += localError;
}
return error;
}
// a timer
struct StopWatch {
using timepoint_t = std::chrono::time_point<std::chrono::steady_clock>;
timepoint_t Start;
//
StopWatch() {
Start = std::chrono::steady_clock::now();
}
//
double elapsed() const {
const auto now = std::chrono::steady_clock::now();
std::chrono::duration<double> elapsed = now - Start;
return elapsed.count();
}
};
//
bool testIfIVFPQ(
const faiss::Index* const index,
const float** pqCoarseCentroidsQ,
const float** pqFineCentroidsQ) {
if (pqFineCentroidsQ == nullptr || pqCoarseCentroidsQ == nullptr) {
return false;
}
const faiss::IndexIVFPQ* const indexQ =
dynamic_cast<const faiss::IndexIVFPQ*>(index);
if (indexQ == nullptr) {
return false;
}
const auto coarseIndexQ =
dynamic_cast<const faiss::IndexFlatCodes*>(indexQ->quantizer);
if (coarseIndexQ == nullptr) {
return false;
}
*pqFineCentroidsQ = indexQ->pq.centroids.data();
*pqCoarseCentroidsQ =
reinterpret_cast<const float*>(coarseIndexQ->codes.data());
return true;
}
bool testIfResidualPQ(
const faiss::Index* const index,
const float** pqCoarseCentroidsQ,
const float** pqFineCentroidsQ) {
if (pqFineCentroidsQ == nullptr || pqCoarseCentroidsQ == nullptr) {
return false;
}
const faiss::Index2Layer* const indexQ =
dynamic_cast<const faiss::Index2Layer*>(index);
if (indexQ == nullptr) {
return false;
}
const auto coarseIndexQ = dynamic_cast<const faiss::MultiIndexQuantizer*>(
indexQ->q1.quantizer);
if (coarseIndexQ == nullptr) {
return false;
}
*pqFineCentroidsQ = indexQ->pq.centroids.data();
*pqCoarseCentroidsQ = coarseIndexQ->pq.centroids.data();
return true;
}
//
template <typename T>
static void verifyIndex2LevelDecoder(
const uint64_t n,
const uint64_t d,
const std::string& description,
const std::shared_ptr<faiss::Index>& index,
const std::vector<uint8_t>& encodedData,
const uint64_t nIterations) {
//
const float* pqFineCentroidsQ = nullptr;
const float* pqCoarseCentroidsQ = nullptr;
//
testIfIVFPQ(index.get(), &pqCoarseCentroidsQ, &pqFineCentroidsQ);
testIfResidualPQ(index.get(), &pqCoarseCentroidsQ, &pqFineCentroidsQ);
//
const size_t codeSize = index->sa_code_size();
// initialize the random engine
std::default_random_engine rng(123);
std::uniform_real_distribution<float> u(0, 1);
// use 1 thread
omp_set_num_threads(1);
//////////////////////////////////////////////////////////////////////////////////////////////////////////
// sequential order
{
std::vector<float> outputFaiss(n * d, 0);
std::vector<float> outputKernel1(n * d, 0);
// faiss
StopWatch swFaiss;
for (uint64_t iter = 0; iter < nIterations; iter++) {
index->sa_decode(n, encodedData.data(), outputFaiss.data());
}
double timeFaiss = swFaiss.elapsed();
// kernels
StopWatch swKernel;
for (int iter = 0; iter < nIterations; iter++) {
for (uint64_t i = 0; i < n; i++) {
T::store(
pqCoarseCentroidsQ,
pqFineCentroidsQ,
encodedData.data() + i * codeSize,
outputKernel1.data() + i * d);
}
}
double timeKernel = swKernel.elapsed();
// evaluate the error
double error = getError(n, d, outputFaiss, outputKernel1);
std::cout << description << "\t" << n << "\t" << d << "\t"
<< "store_seq"
<< "\t" << nIterations << "\t" << timeFaiss << "\t"
<< timeKernel << "\t" << error << std::endl;
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
// random order
// generate a random order of points
std::uniform_int_distribution<uint64_t> un(0, n - 1);
std::vector<uint64_t> pointIncidesToDecode(nIterations * n, 0);
for (uint64_t i = 0; i < nIterations * n; i++) {
pointIncidesToDecode[i] = un(rng);
}
{
std::vector<float> outputFaiss(n * d, 0);
std::vector<float> outputKernel1(n * d, 0);
// faiss
StopWatch swFaiss;
for (uint64_t iter = 0; iter < nIterations; iter++) {
for (uint64_t i = 0; i < n; i++) {
const auto pointIdx = pointIncidesToDecode[i + iter * n];
index->sa_decode(
1,
encodedData.data() + pointIdx * codeSize,
outputFaiss.data() + i * d);
}
}
const double timeFaiss = swFaiss.elapsed();
// kernels
StopWatch swKernel;
for (uint64_t iter = 0; iter < nIterations; iter++) {
for (uint64_t i = 0; i < n; i++) {
const auto pointIdx = pointIncidesToDecode[i + iter * n];
T::store(
pqCoarseCentroidsQ,
pqFineCentroidsQ,
encodedData.data() + pointIdx * codeSize,
outputKernel1.data() + i * d);
}
}
const double timeKernel = swKernel.elapsed();
// evaluate the error
const double error = getError(n, d, outputFaiss, outputKernel1);
std::cout << description << "\t" << n << "\t" << d << "\t"
<< "store_rnd"
<< "\t" << nIterations << "\t" << timeFaiss << "\t"
<< timeKernel << "\t" << error << std::endl;
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
// random accumulate
{
std::vector<float> outputFaiss(n * d, 0);
std::vector<float> outputKernel1(n * d, 0);
std::vector<float> outputKernel2(n * d, 0);
std::vector<float> outputKernel2u(n * d, 0);
std::vector<float> outputKernel3(n * d, 0);
std::vector<float> outputKernel3u(n * d, 0);
// a temporary buffer for faiss
std::vector<float> tempFaiss(d, 0);
// random weights
std::vector<float> weights(nIterations * n, 0);
for (uint64_t i = 0; i < nIterations * n; i++) {
weights[i] = u(rng);
}
// faiss
StopWatch swFaiss;
for (uint64_t i = 0; i < n; i++) {
for (uint64_t iter = 0; iter < nIterations; iter++) {
const auto pointIdx =
pointIncidesToDecode[i * nIterations + iter];
const auto weight = weights[i * nIterations + iter];
index->sa_decode(
1,
encodedData.data() + pointIdx * codeSize,
tempFaiss.data());
for (uint64_t j = 0; j < d; j++)
outputFaiss[i * d + j] += weight * tempFaiss[j];
}
}
const double timeFaiss = swFaiss.elapsed();
// kernels: accum 1 point
StopWatch swKernel1;
for (uint64_t i = 0; i < n; i++) {
for (uint64_t iter = 0; iter < nIterations; iter++) {
const auto pointIdx =
pointIncidesToDecode[i * nIterations + iter];
const auto weight = weights[i * nIterations + iter];
T::accum(
pqCoarseCentroidsQ,
pqFineCentroidsQ,
encodedData.data() + pointIdx * codeSize,
weight,
outputKernel1.data() + i * d);
}
}
const double timeKernel1 = swKernel1.elapsed();
// evaluate the error
const double error1 = getError(n, d, outputFaiss, outputKernel1);
std::cout << description << "\t" << n << "\t" << d << "\t"
<< "accum_rnd"
<< "\t" << nIterations << "\t" << timeFaiss << "\t"
<< timeKernel1 << "\t" << error1 << std::endl;
// kernels: accum 2 points, shared centroids
StopWatch swKernel2;
for (uint64_t i = 0; i < n; i++) {
for (uint64_t iter = 0; iter < nIterations; iter += 2) {
const auto pointIdx0 =
pointIncidesToDecode[i * nIterations + iter + 0];
const auto weight0 = weights[i * nIterations + iter + 0];
const auto pointIdx1 =
pointIncidesToDecode[i * nIterations + iter + 1];
const auto weight1 = weights[i * nIterations + iter + 1];
T::accum(
pqCoarseCentroidsQ,
pqFineCentroidsQ,
encodedData.data() + pointIdx0 * codeSize,
weight0,
encodedData.data() + pointIdx1 * codeSize,
weight1,
outputKernel2.data() + i * d);
}
}
const double timeKernel2 = swKernel2.elapsed();
// evaluate the error
const double error2 = getError(n, d, outputFaiss, outputKernel2);
std::cout << description << "\t" << n << "\t" << d << "\t"
<< "accum2_rnd"
<< "\t" << nIterations << "\t" << timeFaiss << "\t"
<< timeKernel2 << "\t" << error2 << std::endl;
// kernels: accum 2 points, unique centroids
StopWatch swKernel2u;
for (uint64_t i = 0; i < n; i++) {
for (uint64_t iter = 0; iter < nIterations; iter += 2) {
const auto pointIdx0 =
pointIncidesToDecode[i * nIterations + iter + 0];
const auto weight0 = weights[i * nIterations + iter + 0];
const auto pointIdx1 =
pointIncidesToDecode[i * nIterations + iter + 1];
const auto weight1 = weights[i * nIterations + iter + 1];
T::accum(
pqCoarseCentroidsQ,
pqFineCentroidsQ,
encodedData.data() + pointIdx0 * codeSize,
weight0,
pqCoarseCentroidsQ,
pqFineCentroidsQ,
encodedData.data() + pointIdx1 * codeSize,
weight1,
outputKernel2u.data() + i * d);
}
}
const double timeKernel2u = swKernel2u.elapsed();
// evaluate the error
const double error2u = getError(n, d, outputFaiss, outputKernel2u);
std::cout << description << "\t" << n << "\t" << d << "\t"
<< "accum2u_rnd"
<< "\t" << nIterations << "\t" << timeFaiss << "\t"
<< timeKernel2u << "\t" << error2u << std::endl;
// kernels: accum 3 points, shared centroids
StopWatch swKernel3;
for (uint64_t i = 0; i < n; i++) {
for (uint64_t iter = 0; iter < nIterations; iter += 3) {
const auto pointIdx0 =
pointIncidesToDecode[i * nIterations + iter + 0];
const auto weight0 = weights[i * nIterations + iter + 0];
const auto pointIdx1 =
pointIncidesToDecode[i * nIterations + iter + 1];
const auto weight1 = weights[i * nIterations + iter + 1];
const auto pointIdx2 =
pointIncidesToDecode[i * nIterations + iter + 2];
const auto weight2 = weights[i * nIterations + iter + 2];
T::accum(
pqCoarseCentroidsQ,
pqFineCentroidsQ,
encodedData.data() + pointIdx0 * codeSize,
weight0,
encodedData.data() + pointIdx1 * codeSize,
weight1,
encodedData.data() + pointIdx2 * codeSize,
weight2,
outputKernel3.data() + i * d);
}
}
const double timeKernel3 = swKernel3.elapsed();
// evaluate the error
const double error3 = getError(n, d, outputFaiss, outputKernel3);
std::cout << description << "\t" << n << "\t" << d << "\t"
<< "accum3_rnd"
<< "\t" << nIterations << "\t" << timeFaiss << "\t"
<< timeKernel3 << "\t" << error3 << std::endl;
// kernels: accum 3 points, unique centroids
StopWatch swKernel3u;
for (uint64_t i = 0; i < n; i++) {
for (uint64_t iter = 0; iter < nIterations; iter += 3) {
const auto pointIdx0 =
pointIncidesToDecode[i * nIterations + iter + 0];
const auto weight0 = weights[i * nIterations + iter + 0];
const auto pointIdx1 =
pointIncidesToDecode[i * nIterations + iter + 1];
const auto weight1 = weights[i * nIterations + iter + 1];
const auto pointIdx2 =
pointIncidesToDecode[i * nIterations + iter + 2];
const auto weight2 = weights[i * nIterations + iter + 2];
T::accum(
pqCoarseCentroidsQ,
pqFineCentroidsQ,
encodedData.data() + pointIdx0 * codeSize,
weight0,
pqCoarseCentroidsQ,
pqFineCentroidsQ,
encodedData.data() + pointIdx1 * codeSize,
weight1,
pqCoarseCentroidsQ,
pqFineCentroidsQ,
encodedData.data() + pointIdx2 * codeSize,
weight2,
outputKernel3u.data() + i * d);
}
}
const double timeKernel3u = swKernel3u.elapsed();
// evaluate the error
const double error3u = getError(n, d, outputFaiss, outputKernel3u);
std::cout << description << "\t" << n << "\t" << d << "\t"
<< "accum3u_rnd"
<< "\t" << nIterations << "\t" << timeFaiss << "\t"
<< timeKernel3u << "\t" << error3u << std::endl;
}
}
//
template <typename T>
static void verifyMinMaxIndex2LevelDecoder(
const uint64_t n,
const uint64_t d,
const std::string& description,
const std::shared_ptr<faiss::Index>& index,
const std::vector<uint8_t>& encodedData,
const uint64_t nIterations) {
//
const float* pqFineCentroidsQ = nullptr;
const float* pqCoarseCentroidsQ = nullptr;
// extract an index that is wrapped with IndexRowwiseMinMaxBase
const std::shared_ptr<faiss::IndexRowwiseMinMaxBase> indexMinMax =
std::dynamic_pointer_cast<faiss::IndexRowwiseMinMaxBase>(index);
auto subIndex = indexMinMax->index;
//
testIfIVFPQ(subIndex, &pqCoarseCentroidsQ, &pqFineCentroidsQ);
testIfResidualPQ(subIndex, &pqCoarseCentroidsQ, &pqFineCentroidsQ);
//
const size_t codeSize = index->sa_code_size();
// initialize the random engine
std::default_random_engine rng(123);
std::uniform_real_distribution<float> u(0, 1);
// use 1 thread
omp_set_num_threads(1);
//////////////////////////////////////////////////////////////////////////////////////////////////////////
// sequential order
{
std::vector<float> outputFaiss(n * d, 0);
std::vector<float> outputKernel1(n * d, 0);
// faiss
StopWatch swFaiss;
for (uint64_t iter = 0; iter < nIterations; iter++) {
index->sa_decode(n, encodedData.data(), outputFaiss.data());
}
double timeFaiss = swFaiss.elapsed();
// kernels
StopWatch swKernel;
for (int iter = 0; iter < nIterations; iter++) {
for (uint64_t i = 0; i < n; i++) {
T::store(
pqCoarseCentroidsQ,
pqFineCentroidsQ,
encodedData.data() + i * codeSize,
outputKernel1.data() + i * d);
}
}
double timeKernel = swKernel.elapsed();
// evaluate the error
double error = getError(n, d, outputFaiss, outputKernel1);
std::cout << description << "\t" << n << "\t" << d << "\t"
<< "store_seq"
<< "\t" << nIterations << "\t" << timeFaiss << "\t"
<< timeKernel << "\t" << error << std::endl;
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
// random order
// generate a random order of points
std::uniform_int_distribution<uint64_t> un(0, n - 1);
std::vector<uint64_t> pointIncidesToDecode(nIterations * n, 0);
for (uint64_t i = 0; i < nIterations * n; i++) {
pointIncidesToDecode[i] = un(rng);
}
{
std::vector<float> outputFaiss(n * d, 0);
std::vector<float> outputKernel1(n * d, 0);
// faiss
StopWatch swFaiss;
for (uint64_t iter = 0; iter < nIterations; iter++) {
for (uint64_t i = 0; i < n; i++) {
const auto pointIdx = pointIncidesToDecode[i + iter * n];
index->sa_decode(
1,
encodedData.data() + pointIdx * codeSize,
outputFaiss.data() + i * d);
}
}
const double timeFaiss = swFaiss.elapsed();
// kernels
StopWatch swKernel;
for (uint64_t iter = 0; iter < nIterations; iter++) {
for (uint64_t i = 0; i < n; i++) {
const auto pointIdx = pointIncidesToDecode[i + iter * n];
T::store(
pqCoarseCentroidsQ,
pqFineCentroidsQ,
encodedData.data() + pointIdx * codeSize,
outputKernel1.data() + i * d);
}
}
const double timeKernel = swKernel.elapsed();
// evaluate the error
const double error = getError(n, d, outputFaiss, outputKernel1);
std::cout << description << "\t" << n << "\t" << d << "\t"
<< "store_rnd"
<< "\t" << nIterations << "\t" << timeFaiss << "\t"
<< timeKernel << "\t" << error << std::endl;
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
// random accumulate
{
std::vector<float> outputFaiss(n * d, 0);
std::vector<float> outputKernel1(n * d, 0);
std::vector<float> outputKernel2(n * d, 0);
std::vector<float> outputKernel2u(n * d, 0);
std::vector<float> outputKernel3(n * d, 0);
std::vector<float> outputKernel3u(n * d, 0);
// a temporary buffer for faiss
std::vector<float> tempFaiss(d, 0);
// random weights
std::vector<float> weights(nIterations * n, 0);
for (uint64_t i = 0; i < nIterations * n; i++) {
weights[i] = u(rng);
}
// faiss
StopWatch swFaiss;
for (uint64_t i = 0; i < n; i++) {
for (uint64_t iter = 0; iter < nIterations; iter++) {
const auto pointIdx =
pointIncidesToDecode[i * nIterations + iter];
const auto weight = weights[i * nIterations + iter];
index->sa_decode(
1,
encodedData.data() + pointIdx * codeSize,
tempFaiss.data());
for (uint64_t j = 0; j < d; j++) {
outputFaiss[i * d + j] += weight * tempFaiss[j];
}
}
}
const double timeFaiss = swFaiss.elapsed();
// kernels: accum 1 point
StopWatch swKernel1;
for (uint64_t i = 0; i < n; i++) {
float outputAccumMin = 0;
for (uint64_t iter = 0; iter < nIterations; iter++) {
const auto pointIdx =
pointIncidesToDecode[i * nIterations + iter];
const auto weight = weights[i * nIterations + iter];
T::accum(
pqCoarseCentroidsQ,
pqFineCentroidsQ,
encodedData.data() + pointIdx * codeSize,
weight,
outputKernel1.data() + i * d,
outputAccumMin);
}
for (uint64_t j = 0; j < d; j++) {
outputKernel1[i * d + j] += outputAccumMin;
}
}
const double timeKernel1 = swKernel1.elapsed();
// evaluate the error
const double error1 = getError(n, d, outputFaiss, outputKernel1);
std::cout << description << "\t" << n << "\t" << d << "\t"
<< "accum_rnd"
<< "\t" << nIterations << "\t" << timeFaiss << "\t"
<< timeKernel1 << "\t" << error1 << std::endl;
// kernels: accum 2 points, shared centroids
StopWatch swKernel2;
for (uint64_t i = 0; i < n; i++) {
float outputAccumMin = 0;
for (uint64_t iter = 0; iter < nIterations; iter += 2) {
const auto pointIdx0 =
pointIncidesToDecode[i * nIterations + iter + 0];
const auto weight0 = weights[i * nIterations + iter + 0];
const auto pointIdx1 =
pointIncidesToDecode[i * nIterations + iter + 1];
const auto weight1 = weights[i * nIterations + iter + 1];
T::accum(
pqCoarseCentroidsQ,
pqFineCentroidsQ,
encodedData.data() + pointIdx0 * codeSize,
weight0,
encodedData.data() + pointIdx1 * codeSize,
weight1,
outputKernel2.data() + i * d,
outputAccumMin);
}
for (uint64_t j = 0; j < d; j++) {
outputKernel2[i * d + j] += outputAccumMin;
}
}
const double timeKernel2 = swKernel2.elapsed();
// evaluate the error
const double error2 = getError(n, d, outputFaiss, outputKernel2);
std::cout << description << "\t" << n << "\t" << d << "\t"
<< "accum2_rnd"
<< "\t" << nIterations << "\t" << timeFaiss << "\t"
<< timeKernel2 << "\t" << error2 << std::endl;
// kernels: accum 2 points, unique centroids
StopWatch swKernel2u;
for (uint64_t i = 0; i < n; i++) {
float outputAccumMin = 0;
for (uint64_t iter = 0; iter < nIterations; iter += 2) {
const auto pointIdx0 =
pointIncidesToDecode[i * nIterations + iter + 0];
const auto weight0 = weights[i * nIterations + iter + 0];
const auto pointIdx1 =
pointIncidesToDecode[i * nIterations + iter + 1];
const auto weight1 = weights[i * nIterations + iter + 1];
T::accum(
pqCoarseCentroidsQ,
pqFineCentroidsQ,
encodedData.data() + pointIdx0 * codeSize,
weight0,
pqCoarseCentroidsQ,
pqFineCentroidsQ,
encodedData.data() + pointIdx1 * codeSize,
weight1,
outputKernel2u.data() + i * d,
outputAccumMin);
}
for (uint64_t j = 0; j < d; j++) {
outputKernel2u[i * d + j] += outputAccumMin;
}
}
const double timeKernel2u = swKernel2u.elapsed();
// evaluate the error
const double error2u = getError(n, d, outputFaiss, outputKernel2u);
std::cout << description << "\t" << n << "\t" << d << "\t"
<< "accum2u_rnd"
<< "\t" << nIterations << "\t" << timeFaiss << "\t"
<< timeKernel2u << "\t" << error2u << std::endl;
// kernels: accum 3 points, shared centroids
StopWatch swKernel3;
for (uint64_t i = 0; i < n; i++) {
float outputAccumMin = 0;
for (uint64_t iter = 0; iter < nIterations; iter += 3) {
const auto pointIdx0 =
pointIncidesToDecode[i * nIterations + iter + 0];
const auto weight0 = weights[i * nIterations + iter + 0];
const auto pointIdx1 =
pointIncidesToDecode[i * nIterations + iter + 1];
const auto weight1 = weights[i * nIterations + iter + 1];
const auto pointIdx2 =
pointIncidesToDecode[i * nIterations + iter + 2];
const auto weight2 = weights[i * nIterations + iter + 2];
T::accum(
pqCoarseCentroidsQ,
pqFineCentroidsQ,
encodedData.data() + pointIdx0 * codeSize,
weight0,
encodedData.data() + pointIdx1 * codeSize,
weight1,
encodedData.data() + pointIdx2 * codeSize,
weight2,
outputKernel3.data() + i * d,
outputAccumMin);
}
for (uint64_t j = 0; j < d; j++) {
outputKernel3[i * d + j] += outputAccumMin;
}
}
const double timeKernel3 = swKernel3.elapsed();
// evaluate the error
const double error3 = getError(n, d, outputFaiss, outputKernel3);
std::cout << description << "\t" << n << "\t" << d << "\t"
<< "accum3_rnd"
<< "\t" << nIterations << "\t" << timeFaiss << "\t"
<< timeKernel3 << "\t" << error3 << std::endl;
// kernels: accum 3 points, unique centroids
StopWatch swKernel3u;
for (uint64_t i = 0; i < n; i++) {
float outputAccumMin = 0;
for (uint64_t iter = 0; iter < nIterations; iter += 3) {
const auto pointIdx0 =
pointIncidesToDecode[i * nIterations + iter + 0];
const auto weight0 = weights[i * nIterations + iter + 0];
const auto pointIdx1 =
pointIncidesToDecode[i * nIterations + iter + 1];
const auto weight1 = weights[i * nIterations + iter + 1];
const auto pointIdx2 =
pointIncidesToDecode[i * nIterations + iter + 2];
const auto weight2 = weights[i * nIterations + iter + 2];
T::accum(
pqCoarseCentroidsQ,
pqFineCentroidsQ,
encodedData.data() + pointIdx0 * codeSize,
weight0,
pqCoarseCentroidsQ,
pqFineCentroidsQ,
encodedData.data() + pointIdx1 * codeSize,
weight1,
pqCoarseCentroidsQ,
pqFineCentroidsQ,
encodedData.data() + pointIdx2 * codeSize,
weight2,
outputKernel3u.data() + i * d,
outputAccumMin);
}
for (uint64_t j = 0; j < d; j++) {
outputKernel3u[i * d + j] += outputAccumMin;
}
}
const double timeKernel3u = swKernel3u.elapsed();
// evaluate the error
const double error3u = getError(n, d, outputFaiss, outputKernel3u);
std::cout << description << "\t" << n << "\t" << d << "\t"
<< "accum3u_rnd"
<< "\t" << nIterations << "\t" << timeFaiss << "\t"
<< timeKernel3u << "\t" << error3u << std::endl;
}
}
//
template <typename T>
static void verifyIndexPQDecoder(
const uint64_t n,
const uint64_t d,
const std::string& description,
const std::shared_ptr<faiss::Index>& index,
const std::vector<uint8_t>& encodedData,
const uint64_t nIterations) {
//
const faiss::IndexPQ* const indexQ =
dynamic_cast<const faiss::IndexPQ*>(index.get());
const float* const pqFineCentroidsQ = indexQ->pq.centroids.data();
//
const size_t codeSize = index->sa_code_size();
// initialize the random engine
std::default_random_engine rng(123);
std::uniform_real_distribution<float> u(0, 1);
// use 1 thread
omp_set_num_threads(1);
//////////////////////////////////////////////////////////////////////////////////////////////////////////
// sequential order
{
std::vector<float> outputFaiss(n * d, 0);
std::vector<float> outputKernel1(n * d, 0);
// faiss
StopWatch swFaiss;
for (uint64_t iter = 0; iter < nIterations; iter++) {
index->sa_decode(n, encodedData.data(), outputFaiss.data());
}
double timeFaiss = swFaiss.elapsed();
// kernels
StopWatch swKernel;
for (int iter = 0; iter < nIterations; iter++) {
for (uint64_t i = 0; i < n; i++) {
T::store(
pqFineCentroidsQ,
encodedData.data() + i * codeSize,
outputKernel1.data() + i * d);
}
}
double timeKernel = swKernel.elapsed();
// evaluate the error
double error = getError(n, d, outputFaiss, outputKernel1);
std::cout << description << "\t" << n << "\t" << d << "\t"
<< "store_seq"
<< "\t" << nIterations << "\t" << timeFaiss << "\t"
<< timeKernel << "\t" << error << std::endl;
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
// random order
// generate a random order of points
std::uniform_int_distribution<uint64_t> un(0, n - 1);
std::vector<uint64_t> pointIncidesToDecode(nIterations * n, 0);
for (uint64_t i = 0; i < nIterations * n; i++) {
pointIncidesToDecode[i] = un(rng);
}
{
std::vector<float> outputFaiss(n * d, 0);
std::vector<float> outputKernel1(n * d, 0);
// faiss
StopWatch swFaiss;
for (uint64_t iter = 0; iter < nIterations; iter++) {
for (uint64_t i = 0; i < n; i++) {
const auto pointIdx = pointIncidesToDecode[i + iter * n];
index->sa_decode(
1,
encodedData.data() + pointIdx * codeSize,
outputFaiss.data() + i * d);
}
}
const double timeFaiss = swFaiss.elapsed();
// kernels
StopWatch swKernel;
for (uint64_t iter = 0; iter < nIterations; iter++) {
for (uint64_t i = 0; i < n; i++) {
const auto pointIdx = pointIncidesToDecode[i + iter * n];
T::store(
pqFineCentroidsQ,
encodedData.data() + pointIdx * codeSize,
outputKernel1.data() + i * d);
}
}
const double timeKernel = swKernel.elapsed();
// evaluate the error
const double error = getError(n, d, outputFaiss, outputKernel1);
std::cout << description << "\t" << n << "\t" << d << "\t"
<< "store_rnd"
<< "\t" << nIterations << "\t" << timeFaiss << "\t"
<< timeKernel << "\t" << error << std::endl;
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////
// random accumulate
{
std::vector<float> outputFaiss(n * d, 0);
std::vector<float> outputKernel1(n * d, 0);
std::vector<float> outputKernel2(n * d, 0);
std::vector<float> outputKernel2u(n * d, 0);
std::vector<float> outputKernel3(n * d, 0);
std::vector<float> outputKernel3u(n * d, 0);
// a temporary buffer for faiss
std::vector<float> tempFaiss(d, 0);
// random weights
std::vector<float> weights(nIterations * n, 0);
for (uint64_t i = 0; i < nIterations * n; i++) {
weights[i] = u(rng);
}
// faiss
StopWatch swFaiss;
for (uint64_t i = 0; i < n; i++) {
for (uint64_t iter = 0; iter < nIterations; iter++) {
const auto pointIdx =
pointIncidesToDecode[i * nIterations + iter];
const auto weight = weights[i * nIterations + iter];
index->sa_decode(
1,
encodedData.data() + pointIdx * codeSize,
tempFaiss.data());
for (uint64_t j = 0; j < d; j++) {
outputFaiss[i * d + j] += weight * tempFaiss[j];
}
}
}
const double timeFaiss = swFaiss.elapsed();
// kernels: accum 1 point
StopWatch swKernel1;
for (uint64_t i = 0; i < n; i++) {
for (uint64_t iter = 0; iter < nIterations; iter++) {
const auto pointIdx =
pointIncidesToDecode[i * nIterations + iter];
const auto weight = weights[i * nIterations + iter];
T::accum(
pqFineCentroidsQ,
encodedData.data() + pointIdx * codeSize,
weight,
outputKernel1.data() + i * d);
}
}
const double timeKernel1 = swKernel1.elapsed();
// evaluate the error
const double error1 = getError(n, d, outputFaiss, outputKernel1);
std::cout << description << "\t" << n << "\t" << d << "\t"
<< "accum_rnd"
<< "\t" << nIterations << "\t" << timeFaiss << "\t"
<< timeKernel1 << "\t" << error1 << std::endl;
// kernels: accum 2 points, shared centroids
StopWatch swKernel2;
for (uint64_t i = 0; i < n; i++) {
for (uint64_t iter = 0; iter < nIterations; iter += 2) {
const auto pointIdx0 =
pointIncidesToDecode[i * nIterations + iter + 0];
const auto weight0 = weights[i * nIterations + iter + 0];
const auto pointIdx1 =
pointIncidesToDecode[i * nIterations + iter + 1];
const auto weight1 = weights[i * nIterations + iter + 1];
T::accum(
pqFineCentroidsQ,
encodedData.data() + pointIdx0 * codeSize,
weight0,
encodedData.data() + pointIdx1 * codeSize,
weight1,