a6926b065d
5fbf7c4fix nits: variable naming, typos (Martin Ankerl)1e0ee90Use best-fit strategy in Arena, now O(log(n)) instead O(n) (Martin Ankerl) Pull request description: This replaces the first-fit algorithm used in the Arena with a best-fit. According to "Dynamic Storage Allocation: A Survey and Critical Review", Wilson et. al. 1995, http://www.scs.stanford.edu/14wi-cs140/sched/readings/wilson.pdf, both startegies work well in practice. The advantage of using best-fit is that we can switch the O(n) allocation to O(log(n)). Additionally, some previously O(log(n)) operations are now O(1) operations by using hash maps. The end effect is that the benchmark runs about 2.5 times faster on my machine: # Benchmark, evals, iterations, total, min, max, median old: BenchLockedPool, 5, 530, 5.25749, 0.00196938, 0.00199755, 0.00198172 new: BenchLockedPool, 5, 1300, 5.11313, 0.000781493, 0.000793314, 0.00078606 I've run all unit tests and benchmarks, and increased the number of iterations so that BenchLockedPool takes about 5 seconds again. Tree-SHA512: 6551e384671f93f10c60df530a29a1954bd265cc305411f665a8756525e5afe2873a8032c797d00b6e8c07e16d9827465d0b662875433147381474a44119ccce
46 lines
1.2 KiB
C++
46 lines
1.2 KiB
C++
// Copyright (c) 2016-2017 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include <bench/bench.h>
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#include <support/lockedpool.h>
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#include <iostream>
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#include <vector>
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#define ASIZE 2048
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#define BITER 5000
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#define MSIZE 2048
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static void BenchLockedPool(benchmark::State& state)
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{
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void *synth_base = reinterpret_cast<void*>(0x08000000);
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const size_t synth_size = 1024*1024;
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Arena b(synth_base, synth_size, 16);
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std::vector<void*> addr;
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for (int x=0; x<ASIZE; ++x)
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addr.push_back(nullptr);
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uint32_t s = 0x12345678;
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while (state.KeepRunning()) {
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for (int x=0; x<BITER; ++x) {
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int idx = s & (addr.size()-1);
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if (s & 0x80000000) {
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b.free(addr[idx]);
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addr[idx] = nullptr;
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} else if(!addr[idx]) {
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addr[idx] = b.alloc((s >> 16) & (MSIZE-1));
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}
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bool lsb = s & 1;
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s >>= 1;
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if (lsb)
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s ^= 0xf00f00f0; // LFSR period 0xf7ffffe0
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}
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}
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for (void *ptr: addr)
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b.free(ptr);
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addr.clear();
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}
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BENCHMARK(BenchLockedPool, 1300);
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