gperftools/benchmark/malloc_bench.cc

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#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>

#include <algorithm>
#include <memory>
#include <new>
#include <random>

#include "run_benchmark.h"

static void bench_fastpath_throughput(long iterations,
                                      uintptr_t param)
{
  size_t sz = 32;
  for (; iterations>0; iterations--) {
    void *p = (operator new)(sz);
    (operator delete)(p);
    // this makes next iteration use different free list. So
    // subsequent iterations may actually overlap in time.
    sz = ((sz * 8191) & 511) + 16;
  }
}

static void bench_fastpath_dependent(long iterations,
                                     uintptr_t param)
{
  size_t sz = 32;
  for (; iterations>0; iterations--) {
    uintptr_t p = reinterpret_cast<uintptr_t>((operator new)(sz));
    // casts are because gcc doesn't like us using p's value after it
    // is freed.
    (operator delete)(reinterpret_cast<void*>(p));

    // this makes next iteration depend on current iteration. But this
    // iteration's free may still overlap with next iteration's malloc
    sz = ((sz | reinterpret_cast<size_t>(p)) & 511) + 16;
  }
}

static void bench_fastpath_simple(long iterations,
                                  uintptr_t param)
{
  size_t sz = static_cast<size_t>(param);
  for (; iterations>0; iterations--) {
    void *p = (operator new)(sz);
    (operator delete)(p);
    // next iteration will use same free list as this iteration. So it
    // should be prevent next iterations malloc to go too far before
    // free done. But using same size will make free "too fast" since
    // we'll hit size class cache.
  }
}

#if __cpp_sized_deallocation
static void bench_fastpath_simple_sized(long iterations,
                                        uintptr_t param)
{
  size_t sz = static_cast<size_t>(param);
  for (; iterations>0; iterations--) {
    void *p = (operator new)(sz);
    (operator delete)(p, sz);
    // next iteration will use same free list as this iteration. So it
    // should be prevent next iterations malloc to go too far before
    // free done. But using same size will make free "too fast" since
    // we'll hit size class cache.
  }
}
#endif  // __cpp_sized_deallocation

#if __cpp_aligned_new
static void bench_fastpath_memalign(long iterations,
                                    uintptr_t param)
{
  size_t sz = static_cast<size_t>(param);
  for (; iterations>0; iterations--) {
    static constexpr std::align_val_t kAlign{32};
    void *p = (operator new)(sz, kAlign);
    (operator delete)(p, sz, kAlign);
    // next iteration will use same free list as this iteration. So it
    // should be prevent next iterations malloc to go too far before
    // free done. But using same size will make free "too fast" since
    // we'll hit size class cache.
  }
}
#endif  // __cpp_aligned_new

static void bench_fastpath_stack(long iterations,
                                 uintptr_t _param)
{

  size_t sz = 64;
  long param = static_cast<long>(_param);
  param = std::max(1l, param);
  std::unique_ptr<void*[]> stack = std::make_unique<void*[]>(param);
  for (; iterations>0; iterations -= param) {
    for (long k = param-1; k >= 0; k--) {
      void *p = (operator new)(sz);
      stack[k] = p;
      // this makes next iteration depend on result of this iteration
      sz = ((sz | reinterpret_cast<size_t>(p)) & 511) + 16;
    }
    for (long k = 0; k < param; k++) {
      (operator delete)(stack[k]);
    }
  }
}

static void bench_fastpath_stack_simple(long iterations,
                                        uintptr_t _param)
{

  size_t sz = 32;
  long param = static_cast<long>(_param);
  param = std::max(1l, param);
  std::unique_ptr<void*[]> stack = std::make_unique<void*[]>(param);
  for (; iterations>0; iterations -= param) {
    for (long k = param-1; k >= 0; k--) {
      void *p = (operator new)(sz);
      stack[k] = p;
    }
    for (long k = 0; k < param; k++) {
#if __cpp_sized_deallocation
      (operator delete)(stack[k], sz);
#else
      (operator delete)(stack[k]);
#endif
    }
  }
}

static void bench_fastpath_rnd_dependent(long iterations,
                                         uintptr_t _param)
{
  static const uintptr_t rnd_c = 1013904223;
  static const uintptr_t rnd_a = 1664525;

  size_t sz = 128;
  if ((_param & (_param - 1))) {
    abort();
  }

  long param = static_cast<long>(_param);
  param = std::max(1l, param);
  std::unique_ptr<void*[]> ptrs = std::make_unique<void*[]>(param);

  for (; iterations>0; iterations -= param) {
    for (int k = param-1; k >= 0; k--) {
      void *p = (operator new)(sz);
      ptrs[k] = p;
      sz = ((sz | reinterpret_cast<size_t>(p)) & 511) + 16;
    }

    // this will iterate through all objects in order that is
    // unpredictable to processor's prefetchers
    uint32_t rnd = 0;
    uint32_t free_idx = 0;
    do {
      (operator delete)(ptrs[free_idx]);
      rnd = rnd * rnd_a + rnd_c;
      free_idx = rnd & (param - 1);
    } while (free_idx != 0);
  }
}

void randomize_one_size_class(size_t size) {
  size_t count = (100<<20) / size;
  auto randomize_buffer = std::make_unique<void*[]>(count);

  for (size_t i = 0; i < count; i++) {
    randomize_buffer[i] = (operator new)(size);
  }

  std::shuffle(randomize_buffer.get(), randomize_buffer.get() + count, std::minstd_rand(rand()));

  for (size_t i = 0; i < count; i++) {
    (operator delete)(randomize_buffer[i]);
  }
}

void randomize_size_classes() {
  randomize_one_size_class(8);
  int i;
  for (i = 16; i < 256; i += 16) {
    randomize_one_size_class(i);
  }
  for (; i < 512; i += 32) {
    randomize_one_size_class(i);
  }
  for (; i < 1024; i += 64) {
    randomize_one_size_class(i);
  }
  for (; i < (4 << 10); i += 128) {
    randomize_one_size_class(i);
  }
  for (; i < (32 << 10); i += 1024) {
    randomize_one_size_class(i);
  }
}

int main(void)
{
  printf("Trying to randomize freelists..."); fflush(stdout);
  randomize_size_classes();
  printf("done.\n");

  report_benchmark("bench_fastpath_throughput", bench_fastpath_throughput, 0);
  report_benchmark("bench_fastpath_dependent", bench_fastpath_dependent, 0);
  report_benchmark("bench_fastpath_simple", bench_fastpath_simple, 64);
  report_benchmark("bench_fastpath_simple", bench_fastpath_simple, 2048);
  report_benchmark("bench_fastpath_simple", bench_fastpath_simple, 16384);

#if __cpp_sized_deallocation
  report_benchmark("bench_fastpath_simple_sized", bench_fastpath_simple_sized, 64);
  report_benchmark("bench_fastpath_simple_sized", bench_fastpath_simple_sized, 2048);
#endif

#if __cpp_aligned_new
  report_benchmark("bench_fastpath_memalign", bench_fastpath_memalign, 64);
  report_benchmark("bench_fastpath_memalign", bench_fastpath_memalign, 2048);
#endif

  for (int i = 8; i <= 512; i <<= 1) {
    report_benchmark("bench_fastpath_stack", bench_fastpath_stack, i);
  }

  report_benchmark("bench_fastpath_stack_simple", bench_fastpath_stack_simple, 32);
  report_benchmark("bench_fastpath_stack_simple", bench_fastpath_stack_simple, 8192);
  report_benchmark("bench_fastpath_stack_simple", bench_fastpath_stack_simple, 32768);

  report_benchmark("bench_fastpath_rnd_dependent", bench_fastpath_rnd_dependent, 32);
  report_benchmark("bench_fastpath_rnd_dependent", bench_fastpath_rnd_dependent, 8192);
  report_benchmark("bench_fastpath_rnd_dependent", bench_fastpath_rnd_dependent, 32768);
  return 0;
}