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fbdb46f5cb
Reviewed By: chadaustin Differential Revision: D17872966 fbshipit-source-id: cd60a364a2146f0dadbeca693b1d4a5d7c97ff63
43 lines
999 B
C++
43 lines
999 B
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This software may be used and distributed according to the terms of the
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* GNU General Public License version 2.
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*/
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#include "eden/fs/benchharness/Bench.h"
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#include <inttypes.h>
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#include <stdio.h>
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#include <time.h>
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namespace facebook {
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namespace eden {
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uint64_t getTime() noexcept {
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timespec ts;
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// CLOCK_MONOTONIC is subject in NTP adjustments. CLOCK_MONOTONIC_RAW would be
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// better but these benchmarks are short and reading CLOCK_MONOTONIC takes 20
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// ns and CLOCK_MONOTONIC_RAW takes 130 ns.
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clock_gettime(CLOCK_MONOTONIC, &ts);
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return ts.tv_sec * 1000000000 + ts.tv_nsec;
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}
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StatAccumulator measureClockOverhead() noexcept {
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constexpr int N = 10000;
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StatAccumulator accum;
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uint64_t last = getTime();
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for (int i = 0; i < N; ++i) {
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uint64_t next = getTime();
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uint64_t elapsed = next - last;
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accum.add(elapsed);
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last = next;
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}
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return accum;
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}
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} // namespace eden
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} // namespace facebook
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