mirror of
https://github.com/scottlamb/moonfire-nvr.git
synced 2025-04-14 08:16:01 -04:00
0aadf227c1
I'm seeing what is possible performance-wise in the current C++ before
trying out Go and Rust implementations.
* use the google benchmark framework and some real data.
* use release builds - I hadn't done this in a while, and there were a
few compile errors that manifested only in release mode. Update the
readme to suggest using a release build.
* optimize the varint decoder and SampleIndexIterator to branch less.
* enable link-time optimization for release builds.
* add some support for feedback-directed optimization. Ideally "make"
would automatically produce the "generate" build outputs with a
different object/library/executable suffix, run the generate
benchmark, and then produce the "use" builds. This is not that fancy;
you have to run an arcane command:
alias cmake='cmake -DCMAKE_BUILD_TYPE=Release'
cmake -DPROFILE_GENERATE=true -DPROFILE_USE=false .. && \
make recording-bench && \
src/recording-bench && \
cmake -DPROFILE_GENERATE=false -DPROFILE_USE=true .. && \
make recording-bench && \
perf stat -e cycles,instructions,branches,branch-misses \
src/recording-bench --benchmark_repetitions=5
That said, the results are dramatic - at least 50% improvement. (The
results weren't stable before as small tweaks to the code caused a
huge shift in performance, presumably something something branch
alignment something something.)
67 lines
2.5 KiB
C++
67 lines
2.5 KiB
C++
// This file is part of Moonfire NVR, a security camera network video recorder.
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// Copyright (C) 2016 Scott Lamb <slamb@slamb.org>
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// In addition, as a special exception, the copyright holders give
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// permission to link the code of portions of this program with the
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// OpenSSL library under certain conditions as described in each
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// individual source file, and distribute linked combinations including
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// the two.
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//
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// You must obey the GNU General Public License in all respects for all
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// of the code used other than OpenSSL. If you modify file(s) with this
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// exception, you may extend this exception to your version of the
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// file(s), but you are not obligated to do so. If you do not wish to do
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// so, delete this exception statement from your version. If you delete
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// this exception statement from all source files in the program, then
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// also delete it here.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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//
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// recording-bench.cc: benchmarks of the recording.h interface.
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#include <benchmark/benchmark.h>
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#include <gflags/gflags.h>
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#include "recording.h"
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#include "testutil.h"
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DECLARE_bool(alsologtostderr);
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static void BM_Iterator(benchmark::State &state) {
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using moonfire_nvr::ReadFileOrDie;
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using moonfire_nvr::SampleIndexIterator;
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// state.PauseTiming();
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std::string index = ReadFileOrDie("../src/testdata/video_sample_index.bin");
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// state.ResumeTiming();
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while (state.KeepRunning()) {
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SampleIndexIterator it(index);
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while (!it.done()) it.Next();
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CHECK(!it.has_error()) << it.error();
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}
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state.SetBytesProcessed(int64_t(state.iterations()) * int64_t(index.size()));
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}
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BENCHMARK(BM_Iterator);
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int main(int argc, char **argv) {
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FLAGS_alsologtostderr = true;
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// Sadly, these two flag-parsing libraries don't appear to get along.
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// google::ParseCommandLineFlags(&argc, &argv, true);
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benchmark::Initialize(&argc, argv);
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google::InitGoogleLogging(argv[0]);
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benchmark::RunSpecifiedBenchmarks();
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return 0;
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}
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