git.sesse.net Git - plocate/blob - bench.cpp

   1 #include <chrono>
   2 #include <fcntl.h>
   3 #include <memory>
   4 #include <stdio.h>
   5 #include <string>
   6 #include <unistd.h>
   7
   8 #define dprintf(...)
   9 //#define dprintf(...) fprintf(stderr, __VA_ARGS__);
  10
  11 #include "db.h"
  12 #include "io_uring_engine.h"
  13 #include "turbopfor-encode.h"
  14 #include "turbopfor.h"
  15 #include "vp4.h"
  16
  17 using namespace std;
  18 using namespace std::chrono;
  19
  20 bool use_debug = false;
  21
  22 int main(void)
  23 {
  24         int fd = open("plocate.db", O_RDONLY);
  25         if (fd == -1) {
  26                 perror("plocate.db");
  27                 exit(1);
  28         }
  29
  30         Header hdr;
  31         complete_pread(fd, &hdr, sizeof(hdr), /*offset=*/0);
  32
  33         unique_ptr<Trigram[]> ht(new Trigram[hdr.hashtable_size + hdr.extra_ht_slots + 1]);
  34         complete_pread(fd, ht.get(), (hdr.hashtable_size + hdr.extra_ht_slots + 1) * sizeof(Trigram), hdr.hash_table_offset_bytes);
  35
  36         size_t posting_list_bytes = 0, own_posting_list_bytes = 0, total_elements = 0, most_bytes_pl = 0;
  37         uint32_t longest_pl = 0;
  38         vector<pair<string, unsigned>> posting_lists;
  39         for (unsigned i = 0; i < hdr.hashtable_size + hdr.extra_ht_slots; ++i) {
  40                 if (ht[i].num_docids == 0) {
  41                         continue;
  42                 }
  43                 size_t len = ht[i + 1].offset - ht[i].offset;
  44                 string str;
  45                 str.resize(len);
  46                 complete_pread(fd, &str[0], len, ht[i].offset);
  47                 posting_lists.emplace_back(move(str), ht[i].num_docids);
  48                 longest_pl = std::max(ht[i].num_docids, longest_pl);
  49                 most_bytes_pl = std::max(len, most_bytes_pl);
  50                 posting_list_bytes += len;
  51                 total_elements += ht[i].num_docids;
  52         }
  53         ht.reset();
  54         fprintf(stderr, "Read %zu posting lists.\n", posting_lists.size());
  55
  56         string encoded_pl;
  57         encoded_pl.resize(longest_pl * 2 + 16384);  // Lots of margin.
  58
  59         size_t num_decode_errors = 0, num_encode_errors = 0;
  60         for (auto &[pl, num_docids] : posting_lists) {
  61                 //fprintf(stderr, "%zu bytes, %u docids\n", pl.size(), num_docids);
  62                 vector<uint32_t> out1, out2;
  63                 out1.resize(num_docids + 128);
  64                 out2.resize(num_docids + 128);
  65                 unsigned char *pldata = reinterpret_cast<unsigned char *>(&pl[0]);
  66                 p4nd1dec128v32(pldata, num_docids, &out1[0]);
  67                 decode_pfor_delta1_128(pldata, num_docids, /*interleaved=*/true, &out2[0]);
  68                 for (unsigned i = 0; i < num_docids; ++i) {
  69                         if (out1[i] != out2[i]) {
  70                                 if (++num_decode_errors < 10) {
  71                                         fprintf(stderr, "Decode error:\n");
  72                                         for (unsigned j = 0; j < num_docids; ++j) {
  73                                                 fprintf(stderr, "%3u: reference=%u ours=%u  (diff=%d)\n", j, out1[j], out2[j], out1[j] - out2[j]);
  74                                         }
  75                                 }
  76                                 break;
  77                         }
  78                 }
  79
  80                 // Test encoding, by encoding with out own implementation
  81                 // and checking that decoding with the reference gives
  82                 // the same result. We do not measure performance (we're slow).
  83                 uint32_t deltas[128];
  84                 unsigned char *ptr = reinterpret_cast<unsigned char *>(&encoded_pl[0]);
  85                 ptr = write_baseval(out1[0], ptr);
  86                 for (unsigned i = 1; i < num_docids; i += 128) {
  87                         unsigned num_docids_this_block = std::min(num_docids - i, 128u);
  88                         for (unsigned j = 0; j < num_docids_this_block; ++j) {
  89                                 deltas[j] = out1[i + j] - out1[i + j - 1] - 1;
  90                         }
  91                         bool interleaved = (num_docids_this_block == 128);
  92                         ptr = encode_pfor_single_block<128>(deltas, num_docids_this_block, interleaved, ptr);
  93                 }
  94                 own_posting_list_bytes += ptr - reinterpret_cast<unsigned char *>(&encoded_pl[0]);
  95
  96                 pldata = reinterpret_cast<unsigned char *>(&encoded_pl[0]);
  97                 p4nd1dec128v32(pldata, num_docids, &out2[0]);
  98                 for (unsigned i = 0; i < num_docids; ++i) {
  99                         if (out1[i] != out2[i]) {
 100                                 if (++num_encode_errors < 10) {
 101                                         fprintf(stderr, "Encode error:\n");
 102                                         for (unsigned j = 0; j < num_docids; ++j) {
 103                                                 fprintf(stderr, "%3u: reference=%u ours=%u  (diff=%d)\n", j, out1[j], out2[j], out1[j] - out2[j]);
 104                                         }
 105                                 }
 106                                 break;
 107                         }
 108                 }
 109         }
 110         fprintf(stderr, "%zu/%zu posting lists had errors in decoding.\n", num_decode_errors, posting_lists.size());
 111         fprintf(stderr, "%zu/%zu posting lists had errors in encoding.\n", num_encode_errors, posting_lists.size());
 112
 113         // Benchmark.
 114         vector<uint32_t> dummy;
 115         dummy.resize(longest_pl + 128);
 116         steady_clock::time_point start = steady_clock::now();
 117         for (auto &[pl, num_docids] : posting_lists) {
 118                 unsigned char *pldata = reinterpret_cast<unsigned char *>(&pl[0]);
 119                 p4nd1dec128v32(pldata, num_docids, &dummy[0]);
 120         }
 121         steady_clock::time_point end = steady_clock::now();
 122         double reference_sec = duration<double>(end - start).count();
 123         fprintf(stderr, "Decoding with reference implementation: %.1f ms\n", 1e3 * reference_sec);
 124
 125         start = steady_clock::now();
 126         for (auto &[pl, num_docids] : posting_lists) {
 127                 unsigned char *pldata = reinterpret_cast<unsigned char *>(&pl[0]);
 128                 decode_pfor_delta1_128(pldata, num_docids, /*interleaved=*/true, &dummy[0]);
 129         }
 130         end = steady_clock::now();
 131         double own_sec = duration<double>(end - start).count();
 132         fprintf(stderr, "Decoding with own implementation: %.3f ms (%.2f%% speed)\n", 1e3 * own_sec, 100.0 * reference_sec / own_sec);
 133         fprintf(stderr, "Size with own implementation: %.1f MB (%.2f%% of reference, %+d bytes)\n", own_posting_list_bytes / 1048576.0, 100.0 * own_posting_list_bytes / posting_list_bytes, int(own_posting_list_bytes) - int(posting_list_bytes));
 134
 135         // Three numbers giving rules of thumb for judging our own implementation:
 136         //
 137         // - Compressed speed is easy to compare to disk I/O, to see the relative importance
 138         // - Uncompressed speed is easy to compare to intersection speeds and memory bandwidth
 139         //   (also very roughly comparable to the benchmark numbers in the TurboPFor README)
 140         // - ns/element gives an absolute measure for plocate (e.g. if we can decompress at
 141         //   1 ns/element, a 10k-element posting list goes by in 0.01 ms, which is way beyond
 142         //   instantaneous in practice).
 143         fprintf(stderr, "%.1f MB/sec (compressed), %.1f MB/sec (uncompressed), %.1f ns/element\n", posting_list_bytes / own_sec / 1048576.0,
 144                 (total_elements * sizeof(uint32_t)) / own_sec / 1048576.0, 1e9 * own_sec / total_elements);
 145 }