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/*
* Copyright (C) 2011 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/* This program tries to benchmark stdio operations like fread() and
* fwrite() with various chunk sizes. We always read/write from /dev/zero
* to ensure that disk speed and caching don't change our results.
*
* We really do this to measure improvements in the low-level stdio
* features.
*/
#include <stdio.h>
#include <time.h>
#include <string.h>
#include <errno.h>
static char buffer[1024*1024];
/* Return current time in milli-seconds, as a double */
static double
now_ms(void)
{
struct timespec ts;
clock_gettime(CLOCK_MONOTONIC, &ts);
return ts.tv_sec*1000. + ts.tv_nsec*1e-6;
}
void read_file(FILE* fp, int chunkSize)
{
int totalSize = sizeof(buffer);
for ( ; totalSize > 0; totalSize -= chunkSize) {
fread(buffer, 1, chunkSize, fp);
}
}
void write_file(FILE* fp, int chunkSize)
{
int totalSize = sizeof(buffer);
for ( ; totalSize > 0; totalSize -= chunkSize) {
fwrite(buffer, 1, chunkSize, fp);
}
}
#define BENCH(op,...) \
do { \
double time_ms = now_ms(); \
op ; \
time_ms = now_ms() - time_ms; \
double bandwidth = sizeof(buffer)*1000./1024./time_ms; \
printf("bench %-30s %8.2f ms (%.1f KB/s) \n", #op, time_ms, bandwidth ); \
} while (0)
int main(void)
{
FILE* fp = fopen("/dev/zero", "rw");
if (fp == NULL) {
fprintf(stderr,"Could not open /dev/zero: %s\n", strerror(errno));
return 1;
}
BENCH(read_file(fp,1));
BENCH(read_file(fp,2));
BENCH(read_file(fp,3));
BENCH(read_file(fp,4));
BENCH(read_file(fp,8));
BENCH(read_file(fp,16));
BENCH(read_file(fp,32));
BENCH(read_file(fp,64));
BENCH(read_file(fp,256));
BENCH(read_file(fp,1024));
BENCH(read_file(fp,4096));
BENCH(read_file(fp,16384));
BENCH(read_file(fp,65536));
BENCH(write_file(fp,1));
BENCH(write_file(fp,2));
BENCH(write_file(fp,3));
BENCH(write_file(fp,4));
BENCH(write_file(fp,8));
BENCH(write_file(fp,16));
BENCH(write_file(fp,32));
BENCH(write_file(fp,64));
BENCH(write_file(fp,256));
BENCH(write_file(fp,1024));
BENCH(write_file(fp,4096));
BENCH(write_file(fp,16384));
BENCH(write_file(fp,65536));
fclose(fp);
return 0;
}
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