158 lines
3.1 KiB
C
158 lines
3.1 KiB
C
/*
|
|
* Test null syscall performance
|
|
*
|
|
* Copyright (C) 2009-2015 Anton Blanchard, IBM
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License
|
|
* as published by the Free Software Foundation; either version
|
|
* 2 of the License, or (at your option) any later version.
|
|
*/
|
|
|
|
#define NR_LOOPS 10000000
|
|
|
|
#include <string.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <unistd.h>
|
|
#include <time.h>
|
|
#include <sys/types.h>
|
|
#include <sys/time.h>
|
|
#include <signal.h>
|
|
|
|
static volatile int soak_done;
|
|
unsigned long long clock_frequency;
|
|
unsigned long long timebase_frequency;
|
|
double timebase_multiplier;
|
|
|
|
static inline unsigned long long mftb(void)
|
|
{
|
|
unsigned long low;
|
|
|
|
asm volatile("mftb %0" : "=r" (low));
|
|
|
|
return low;
|
|
}
|
|
|
|
static void sigalrm_handler(int unused)
|
|
{
|
|
soak_done = 1;
|
|
}
|
|
|
|
/*
|
|
* Use a timer instead of busy looping on clock_gettime() so we don't
|
|
* pollute profiles with glibc and VDSO hits.
|
|
*/
|
|
static void cpu_soak_usecs(unsigned long usecs)
|
|
{
|
|
struct itimerval val;
|
|
|
|
memset(&val, 0, sizeof(val));
|
|
val.it_value.tv_usec = usecs;
|
|
|
|
signal(SIGALRM, sigalrm_handler);
|
|
setitimer(ITIMER_REAL, &val, NULL);
|
|
|
|
while (1) {
|
|
if (soak_done)
|
|
break;
|
|
}
|
|
|
|
signal(SIGALRM, SIG_DFL);
|
|
}
|
|
|
|
/*
|
|
* This only works with recent kernels where cpufreq modifies
|
|
* /proc/cpuinfo dynamically.
|
|
*/
|
|
static void get_proc_frequency(void)
|
|
{
|
|
FILE *f;
|
|
char line[128];
|
|
char *p, *end;
|
|
unsigned long v;
|
|
double d;
|
|
char *override;
|
|
|
|
/* Try to get out of low power/low frequency mode */
|
|
cpu_soak_usecs(0.25 * 1000000);
|
|
|
|
f = fopen("/proc/cpuinfo", "r");
|
|
if (f == NULL)
|
|
return;
|
|
|
|
timebase_frequency = 0;
|
|
|
|
while (fgets(line, sizeof(line), f) != NULL) {
|
|
if (strncmp(line, "timebase", 8) == 0) {
|
|
p = strchr(line, ':');
|
|
if (p != NULL) {
|
|
v = strtoull(p + 1, &end, 0);
|
|
if (end != p + 1)
|
|
timebase_frequency = v;
|
|
}
|
|
}
|
|
|
|
if (((strncmp(line, "clock", 5) == 0) ||
|
|
(strncmp(line, "cpu MHz", 7) == 0))) {
|
|
p = strchr(line, ':');
|
|
if (p != NULL) {
|
|
d = strtod(p + 1, &end);
|
|
if (end != p + 1) {
|
|
/* Find fastest clock frequency */
|
|
if ((d * 1000000ULL) > clock_frequency)
|
|
clock_frequency = d * 1000000ULL;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fclose(f);
|
|
|
|
override = getenv("FREQUENCY");
|
|
if (override)
|
|
clock_frequency = strtoull(override, NULL, 10);
|
|
|
|
if (timebase_frequency)
|
|
timebase_multiplier = (double)clock_frequency
|
|
/ timebase_frequency;
|
|
else
|
|
timebase_multiplier = 1;
|
|
}
|
|
|
|
static void do_null_syscall(unsigned long nr)
|
|
{
|
|
unsigned long i;
|
|
|
|
for (i = 0; i < nr; i++)
|
|
getppid();
|
|
}
|
|
|
|
#define TIME(A, STR) \
|
|
|
|
int main(void)
|
|
{
|
|
unsigned long tb_start, tb_now;
|
|
struct timespec tv_start, tv_now;
|
|
unsigned long long elapsed_ns, elapsed_tb;
|
|
|
|
get_proc_frequency();
|
|
|
|
clock_gettime(CLOCK_MONOTONIC, &tv_start);
|
|
tb_start = mftb();
|
|
|
|
do_null_syscall(NR_LOOPS);
|
|
|
|
clock_gettime(CLOCK_MONOTONIC, &tv_now);
|
|
tb_now = mftb();
|
|
|
|
elapsed_ns = (tv_now.tv_sec - tv_start.tv_sec) * 1000000000ULL +
|
|
(tv_now.tv_nsec - tv_start.tv_nsec);
|
|
elapsed_tb = tb_now - tb_start;
|
|
|
|
printf("%10.2f ns %10.2f cycles\n", (float)elapsed_ns / NR_LOOPS,
|
|
(float)elapsed_tb * timebase_multiplier / NR_LOOPS);
|
|
|
|
return 0;
|
|
}
|