* Pierre Peiffer <[email protected]> wrote:
> [...] Any measure will be difficult to do with only FUTEX_WAIT/WAKE.
that's not a problem - just do such a measurement and show that it does
/not/ impact performance measurably. That's what we want to know...
> (*) I'll try the volano bench, if I have time.
yeah. As an alternative, it might be a good idea to pthread-ify
hackbench.c - that should replicate the Volano workload pretty
accurately. I've attached hackbench.c. (it's process based right now, so
it wont trigger contended futex ops)
Ingo
/* Test groups of 20 processes spraying to 20 receivers */
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <sys/poll.h>
#define DATASIZE 100
static unsigned int loops = 100;
static int use_pipes = 0;
static void barf(const char *msg)
{
fprintf(stderr, "%s (error: %s)\n", msg, strerror(errno));
exit(1);
}
static void fdpair(int fds[2])
{
if (use_pipes) {
if (pipe(fds) == 0)
return;
} else {
if (socketpair(AF_UNIX, SOCK_STREAM, 0, fds) == 0)
return;
}
barf("Creating fdpair");
}
/* Block until we're ready to go */
static void ready(int ready_out, int wakefd)
{
char dummy;
struct pollfd pollfd = { .fd = wakefd, .events = POLLIN };
/* Tell them we're ready. */
if (write(ready_out, &dummy, 1) != 1)
barf("CLIENT: ready write");
/* Wait for "GO" signal */
if (poll(&pollfd, 1, -1) != 1)
barf("poll");
}
/* Sender sprays loops messages down each file descriptor */
static void sender(unsigned int num_fds,
int out_fd[num_fds],
int ready_out,
int wakefd)
{
char data[DATASIZE];
unsigned int i, j;
ready(ready_out, wakefd);
/* Now pump to every receiver. */
for (i = 0; i < loops; i++) {
for (j = 0; j < num_fds; j++) {
int ret, done = 0;
again:
ret = write(out_fd[j], data + done, sizeof(data)-done);
if (ret < 0)
barf("SENDER: write");
done += ret;
if (done < sizeof(data))
goto again;
}
}
}
/* One receiver per fd */
static void receiver(unsigned int num_packets,
int in_fd,
int ready_out,
int wakefd)
{
unsigned int i;
/* Wait for start... */
ready(ready_out, wakefd);
/* Receive them all */
for (i = 0; i < num_packets; i++) {
char data[DATASIZE];
int ret, done = 0;
again:
ret = read(in_fd, data + done, DATASIZE - done);
if (ret < 0)
barf("SERVER: read");
done += ret;
if (done < DATASIZE)
goto again;
}
}
/* One group of senders and receivers */
static unsigned int group(unsigned int num_fds,
int ready_out,
int wakefd)
{
unsigned int i;
unsigned int out_fds[num_fds];
for (i = 0; i < num_fds; i++) {
int fds[2];
/* Create the pipe between client and server */
fdpair(fds);
/* Fork the receiver. */
switch (fork()) {
case -1: barf("fork()");
case 0:
close(fds[1]);
receiver(num_fds*loops, fds[0], ready_out, wakefd);
exit(0);
}
out_fds[i] = fds[1];
close(fds[0]);
}
/* Now we have all the fds, fork the senders */
for (i = 0; i < num_fds; i++) {
switch (fork()) {
case -1: barf("fork()");
case 0:
sender(num_fds, out_fds, ready_out, wakefd);
exit(0);
}
}
/* Close the fds we have left */
for (i = 0; i < num_fds; i++)
close(out_fds[i]);
/* Return number of children to reap */
return num_fds * 2;
}
int main(int argc, char *argv[])
{
unsigned int i, num_groups, total_children;
struct timeval start, stop, diff;
unsigned int num_fds = 20;
int readyfds[2], wakefds[2];
char dummy;
if (argv[1] && strcmp(argv[1], "-pipe") == 0) {
use_pipes = 1;
argc--;
argv++;
}
if (argc != 2 || (num_groups = atoi(argv[1])) == 0)
barf("Usage: hackbench [-pipe] <num groups>\n");
fdpair(readyfds);
fdpair(wakefds);
total_children = 0;
for (i = 0; i < num_groups; i++)
total_children += group(num_fds, readyfds[1], wakefds[0]);
/* Wait for everyone to be ready */
for (i = 0; i < total_children; i++)
if (read(readyfds[0], &dummy, 1) != 1)
barf("Reading for readyfds");
gettimeofday(&start, NULL);
/* Kick them off */
if (write(wakefds[1], &dummy, 1) != 1)
barf("Writing to start them");
/* Reap them all */
for (i = 0; i < total_children; i++) {
int status;
wait(&status);
if (!WIFEXITED(status))
exit(1);
}
gettimeofday(&stop, NULL);
/* Print time... */
timersub(&stop, &start, &diff);
printf("Time: %lu.%03lu\n", diff.tv_sec, diff.tv_usec/1000);
exit(0);
}
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