* gcc -Wall -Werror -O3 -static -o ctx ctx.c
*/
#define errx(x,y...) { fprintf(stderr, y); fprintf(stderr, "\n"); exit(x); }
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/time.h>
#include <signal.h>
#if defined (LWP)
#include <sys/ucontext.h>
#include <sys/lwp.h>
#endif
#define ITERATIONS 8192
#define PASSES 50
int fd0[2], fd1[2];
unsigned long elapsed_times[ITERATIONS];
unsigned long overhead;
pid_t childpid;
static void
usage(void)
{
printf("ctx [-hl]\n");
exit(1);
}
static void
child(void)
{
int ch;
ch = 0;
if (write(fd1[1], &ch, 1) != 1)
errx(1, "child write failed");
while (1) {
if (read(fd0[0], &ch, 1) != 1)
errx(1, "child read failed");
if (write(fd1[1], &ch, 1) != 1)
errx(1, "child write failed");
}
}
static void
dump_results(void)
{
unsigned long min_time, max_time, sum;
int i;
min_time = elapsed_times[0];
max_time = elapsed_times[0];
sum = 0;
for (i=1; i<ITERATIONS; i++) {
if (elapsed_times[i] < min_time)
min_time = elapsed_times[i];
if (elapsed_times[i] > max_time)
max_time = elapsed_times[i];
sum += elapsed_times[i] - overhead;
}
min_time -= overhead;
max_time -= overhead;
printf("min latency: %f\n", (double)min_time / PASSES);
printf("max latency: %f\n", (double)max_time / PASSES);
printf("mean latency: %f\n", (double)sum / ITERATIONS / PASSES);
}
int
main(int argc, char *argv[])
{
int i, ch, count;
struct timeval before, after;
unsigned long elapsed;
int use_lwps = 0;
memset(elapsed_times, 0, ITERATIONS);
while ((ch = getopt(argc, argv, "hl")) != -1) {
switch (ch) {
case 'l':
#if defined(LWP)
use_lwps = 1;
#else
errx(1, "not supported");
#endif
break;
case 'h':
usage();
}
}
argc -= optind;
argv += optind;
sleep(1);
if (pipe(fd0) != 0)
errx(1, "Unable to create pipe");
if (pipe(fd1) != 0)
errx(1, "Unable to create pipe");
* Determine overhead
*/
for (count=0; count<2; count++) {
gettimeofday(&before, NULL);
for (i=0; i<2*(PASSES/2); i++) {
ch = 0;
write(fd0[1], &ch, 1);
read(fd0[0], &ch, 1);
}
gettimeofday(&after, NULL);
overhead = 1000000 * (after.tv_sec - before.tv_sec);
overhead += after.tv_usec - before.tv_usec;
}
if (use_lwps) {
#if defined(LWP)
ucontext_t u;
ucontext_t *contextp;
int stacksize = 65536;
void *stackbase;
lwpid_t l;
int error;
getcontext(&u);
contextp = (ucontext_t *)malloc(sizeof(ucontext_t));
stackbase = malloc(stacksize);
sigprocmask(SIG_SETMASK, NULL, &contextp->uc_sigmask);
_lwp_makecontext(contextp, child, NULL, NULL,
stackbase, stacksize);
error = _lwp_create(contextp, 0, &l);
if (error)
errx(1, "error _lwp_create");
#endif
} else {
switch (childpid = fork()) {
case 0:
child();
case -1:
errx(1, "error forking");
break;
}
}
ch = 0;
if (read(fd1[0], &ch, 1) != 1)
errx(1, "parent read failed");
for (count=0; count<ITERATIONS; count++) {
gettimeofday(&before, NULL);
for (i=0; i<PASSES/2; i++) {
ch = 0;
if (write(fd0[1], &ch, 1) != 1)
errx(1, "parent write failed");
if (read(fd1[0], &ch, 1) != 1)
errx(1, "parent read failed");
}
gettimeofday(&after, NULL);
elapsed = 1000000 * (after.tv_sec - before.tv_sec);
elapsed += after.tv_usec - before.tv_usec;
elapsed_times[count] = elapsed;
}
if (!use_lwps)
kill(childpid, SIGTERM);
dump_results();
return (0);
}
* PMAX_SA:
*
* min latency: 93.100000
* max latency: 150.700000
* mean latency: 100.857581
*
* PMAX_CHOOSEPROC:
*
* min latency: 49.350000
* max latency: 76.750000
* mean latency: 54.141626
*
* PMAX_OLD:
*
* min latency: 54.750000
* max latency: 76.050000
* mean latency: 60.088654
*
* HP300_SA:
*
* min latency: 352.560000
* max latency: 402.960000
* mean latency: 367.836250
*
* HP300_CHOOSEPROC:
*
* min latency: 129.200000
* max latency: 187.040000
* mean latency: 142.528223
*
* HP300_OLD:
*
* min latency: 357.360000
* max latency: 414.400000
* mean latency: 372.436104
*
*/
