benchmarks/stdio_benchmark.cpp

/*
 * Copyright (C) 2014 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <err.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdio_ext.h>
#include <stdlib.h>

#include <android-base/file.h>
#include <benchmark/benchmark.h>
#include "util.h"

static void FillFile(TemporaryFile& tf) {
  char line[256];
  memset(line, 'x', sizeof(line));
  line[sizeof(line) - 1] = '\0';

  FILE* fp = fopen(tf.path, "we");
  for (size_t i = 0; i < 4096; ++i) fputs(line, fp);
  fclose(fp);
}

template <typename Fn>
void ReadWriteTest(benchmark::State& state, Fn f, bool buffered) {
  size_t chunk_size = state.range(0);

  // /dev/zero copies zeroes if you read from it and discards writes.
  //
  // This is fine for the purpose of measuring stdio overhead
  // rather than kernel/fs performance.
  // (Old versions of stdio would copy reads/writes larger than
  // the stdio buffer through the stdio buffer in chunks,
  // rather than directly to the user's destination.)
  FILE* fp = fopen("/dev/zero", "r+e");
  __fsetlocking(fp, FSETLOCKING_BYCALLER);
  char* buf = new char[chunk_size];

  if (!buffered) {
    setvbuf(fp, nullptr, _IONBF, 0);
  }

  while (state.KeepRunning()) {
    if (f(buf, chunk_size, 1, fp) != 1) {
      errx(1, "ERROR: op of %zu bytes failed.", chunk_size);
    }
  }

  state.SetBytesProcessed(int64_t(state.iterations()) * int64_t(chunk_size));
  delete[] buf;
  fclose(fp);
}

void BM_stdio_fread(benchmark::State& state) {
  ReadWriteTest(state, fread, true);
}
BIONIC_BENCHMARK_WITH_ARG(BM_stdio_fread, "AT_COMMON_SIZES");

void BM_stdio_fwrite(benchmark::State& state) {
  ReadWriteTest(state, fwrite, true);
}
BIONIC_BENCHMARK_WITH_ARG(BM_stdio_fwrite, "AT_COMMON_SIZES");

void BM_stdio_fread_unbuffered(benchmark::State& state) {
  ReadWriteTest(state, fread, false);
}
BIONIC_BENCHMARK_WITH_ARG(BM_stdio_fread_unbuffered, "AT_COMMON_SIZES");

void BM_stdio_fwrite_unbuffered(benchmark::State& state) {
  ReadWriteTest(state, fwrite, false);
}
BIONIC_BENCHMARK_WITH_ARG(BM_stdio_fwrite_unbuffered, "AT_COMMON_SIZES");

#if !defined(__GLIBC__)
static void FopenFgetlnFclose(benchmark::State& state, bool no_locking) {
  TemporaryFile tf;
  FillFile(tf);
  while (state.KeepRunning()) {
    FILE* fp = fopen(tf.path, "re");
    if (no_locking) __fsetlocking(fp, FSETLOCKING_BYCALLER);
    size_t length;
    while (fgetln(fp, &length) != nullptr) {
    }
    fclose(fp);
  }
}

static void BM_stdio_fopen_fgetln_fclose_locking(benchmark::State& state) {
  FopenFgetlnFclose(state, false);
}
BIONIC_BENCHMARK(BM_stdio_fopen_fgetln_fclose_locking);

void BM_stdio_fopen_fgetln_fclose_no_locking(benchmark::State& state) {
  FopenFgetlnFclose(state, true);
}
BIONIC_BENCHMARK(BM_stdio_fopen_fgetln_fclose_no_locking);
#endif

static void FopenFgetsFclose(benchmark::State& state, bool no_locking) {
  TemporaryFile tf;
  FillFile(tf);
  char buf[BUFSIZ];
  while (state.KeepRunning()) {
    FILE* fp = fopen(tf.path, "re");
    if (no_locking) __fsetlocking(fp, FSETLOCKING_BYCALLER);
    while (fgets(buf, sizeof(buf), fp) != nullptr) {
    }
    fclose(fp);
  }
}

static void BM_stdio_fopen_fgets_fclose_locking(benchmark::State& state) {
  FopenFgetsFclose(state, false);
}
BIONIC_BENCHMARK(BM_stdio_fopen_fgets_fclose_locking);

void BM_stdio_fopen_fgets_fclose_no_locking(benchmark::State& state) {
  FopenFgetsFclose(state, true);
}
BIONIC_BENCHMARK(BM_stdio_fopen_fgets_fclose_no_locking);

static void FopenGetlineFclose(benchmark::State& state, bool no_locking) {
  TemporaryFile tf;
  FillFile(tf);
  while (state.KeepRunning()) {
    FILE* fp = fopen(tf.path, "re");
    if (no_locking) __fsetlocking(fp, FSETLOCKING_BYCALLER);
    char* line = nullptr;
    size_t n = 0;
    while (getline(&line, &n, fp) != -1) {
    }
    free(line);
    fclose(fp);
  }
}

static void BM_stdio_fopen_getline_fclose_locking(benchmark::State& state) {
  FopenGetlineFclose(state, false);
}
BIONIC_BENCHMARK(BM_stdio_fopen_getline_fclose_locking);

void BM_stdio_fopen_getline_fclose_no_locking(benchmark::State& state) {
  FopenGetlineFclose(state, true);
}
BIONIC_BENCHMARK(BM_stdio_fopen_getline_fclose_no_locking);

static void FopenFgetcFclose(benchmark::State& state, bool no_locking) {
  size_t nbytes = state.range(0);
  while (state.KeepRunning()) {
    FILE* fp = fopen("/dev/zero", "re");
    if (no_locking) __fsetlocking(fp, FSETLOCKING_BYCALLER);
    for (size_t i = 0; i < nbytes; ++i) {
      benchmark::DoNotOptimize(fgetc(fp));
    }
    fclose(fp);
  }
}

static void BM_stdio_fopen_fgetc_fclose_locking(benchmark::State& state) {
  FopenFgetcFclose(state, false);
}
BIONIC_BENCHMARK_WITH_ARG(BM_stdio_fopen_fgetc_fclose_locking, "1024");

void BM_stdio_fopen_fgetc_fclose_no_locking(benchmark::State& state) {
  FopenFgetcFclose(state, true);
}
BIONIC_BENCHMARK_WITH_ARG(BM_stdio_fopen_fgetc_fclose_no_locking, "1024");

static void BM_stdio_printf_literal(benchmark::State& state) {
  while (state.KeepRunning()) {
    char buf[BUFSIZ];
    snprintf(buf, sizeof(buf), "this is just a literal string with no format specifiers");
  }
}
BIONIC_BENCHMARK(BM_stdio_printf_literal);

static void BM_stdio_printf_s(benchmark::State& state) {
  while (state.KeepRunning()) {
    char buf[BUFSIZ];
    snprintf(buf, sizeof(buf), "this is a more typical error message with detail: %s",
             "No such file or directory");
  }
}
BIONIC_BENCHMARK(BM_stdio_printf_s);

static void BM_stdio_printf_d(benchmark::State& state) {
  while (state.KeepRunning()) {
    char buf[BUFSIZ];
    snprintf(buf, sizeof(buf), "this is a more typical error message with detail: %d", 123456);
  }
}
BIONIC_BENCHMARK(BM_stdio_printf_d);

static void BM_stdio_printf_1$s(benchmark::State& state) {
  while (state.KeepRunning()) {
    char buf[BUFSIZ];
    snprintf(buf, sizeof(buf), "this is a more typical error message with detail: %1$s",
             "No such file or directory");
  }
}
BIONIC_BENCHMARK(BM_stdio_printf_1$s);

static void BM_stdio_scanf_s(benchmark::State& state) {
  while (state.KeepRunning()) {
    char s[BUFSIZ];
    if (sscanf("file /etc/passwd", "file %s", s) != 1) abort();
  }
}
BIONIC_BENCHMARK(BM_stdio_scanf_s);

static void BM_stdio_scanf_d(benchmark::State& state) {
  while (state.KeepRunning()) {
    int i;
    if (sscanf("size 12345", "size %d", &i) != 1) abort();
  }
}
BIONIC_BENCHMARK(BM_stdio_scanf_d);

// Parsing maps is a common use of sscanf with a relatively complex format string.
static void BM_stdio_scanf_maps(benchmark::State& state) {
  while (state.KeepRunning()) {
    uintptr_t start;
    uintptr_t end;
    uintptr_t offset;
    char permissions[5];
    int name_pos;
    if (sscanf("6f000000-6f01e000 rwxp 00000000 00:0c 16389419   /system/lib/libcomposer.so",
               "%" PRIxPTR "-%" PRIxPTR " %4s %" PRIxPTR " %*x:%*x %*d %n",
               &start, &end, permissions, &offset, &name_pos) != 4) abort();
  }
}
BIONIC_BENCHMARK(BM_stdio_scanf_maps);

// Hard-coded equivalent of the maps sscanf from libunwindstack/Maps.cpp for a baseline.
static int ParseMap(const char* line, const char* /*fmt*/, uintptr_t* start, uintptr_t* end,
                    char* permissions, uintptr_t* offset, int* name_pos) __attribute__((noinline)) {
  char* str;
  const char* old_str = line;

  // "%" PRIxPTR "-"
  *start = strtoul(old_str, &str, 16);
  if (old_str == str || *str++ != '-') return 0;

  // "%" PRIxPTR " "
  old_str = str;
  *end = strtoul(old_str, &str, 16);
  if (old_str == str || !std::isspace(*str++)) return 0;
  while (std::isspace(*str)) str++;

  // "%4s "
  if (*str == '\0') return 0;
  permissions[0] = *str;
  str++;
  permissions[1] = *str;
  str++;
  permissions[2] = *str;
  str++;
  permissions[3] = *str;
  str++;
  permissions[4] = 0;
  if (!std::isspace(*str++)) return 0;

  // "%" PRIxPTR " "
  old_str = str;
  *offset = strtoul(old_str, &str, 16);
  if (old_str == str || !std::isspace(*str)) return 0;

  // "%*x:%*x "
  old_str = str;
  (void)strtoul(old_str, &str, 16);
  if (old_str == str || *str++ != ':') return 0;
  if (std::isspace(*str)) return 0;
  old_str = str;
  (void)strtoul(str, &str, 16);
  if (old_str == str || !std::isspace(*str++)) return 0;

  // "%*d "
  old_str = str;
  (void)strtoul(old_str, &str, 10);
  if (old_str == str || (!std::isspace(*str) && *str != '\0')) return 0;
  while (std::isspace(*str)) str++;

  // "%n"
  *name_pos = (str - line);
  return 4;
}

static void BM_stdio_scanf_maps_baseline(benchmark::State& state) {
  while (state.KeepRunning()) {
    uintptr_t start;
    uintptr_t end;
    uintptr_t offset;
    char permissions[5];
    int name_pos;
    if (ParseMap("6f000000-6f01e000 rwxp 00000000 00:0c 16389419   /system/lib/libcomposer.so",
               "%" PRIxPTR "-%" PRIxPTR " %4s %" PRIxPTR " %*x:%*x %*d %n",
               &start, &end, permissions, &offset, &name_pos) != 4) abort();
  }
}
BIONIC_BENCHMARK(BM_stdio_scanf_maps_baseline);