Improve hackbench

Zhang, Yanmin
2008-01-04T06:09:20Z

hackbench is to test Linux scheduler. The original program is at
http://devresources.linux-foundation.org/craiger/hackbench/src/hackbench.c
Based on this multi-process version, a nice person created a multi-thread
version. Pls. see
http://www.bullopensource.org/posix/pi-futex/hackbench_pth.c

When I integrated them into my automation testing system, I found
a couple of issues and did some improvements.

1) Merge hackbench: I integrated hackbench_pth.c into hackbench and added a
new parameter which can be used to choose process mode or thread mode. The
default mode is process.

2) It runs too fast and ends in a couple of seconds. Sometimes it's too hard to debug
the issues. On my ia64 Montecito machines, the result looks weird when comparing
process mode and thread mode.
I want a stable result and hope the testing could run for a stable longer time, so I
might use performance tools to debug issues.
I added another new parameter,`loops`, which can be used to change variable loops,
so more messages will be passed from writers to receivers. Parameter 'loops' is equal to
100 by default.

For example on my 8-core x86_64:
[ymzhang@lkp-st01-x8664 hackbench]$ uname -a
Linux lkp-st01-x8664 2.6.24-rc6 #1 SMP Fri Dec 21 08:32:31 CST 2007 x86_64 x86_64 x86_64 GNU/Linux
[ymzhang@lkp-st01-x8664 hackbench]$ ./hackbench
Usage: hackbench [-pipe] <num groups> [process|thread] [loops]
[ymzhang@lkp-st01-x8664 hackbench]$ ./hackbench 150 process 1000
Time: 151.533
[ymzhang@lkp-st01-x8664 hackbench]$ ./hackbench 150 thread 1000
Time: 153.666

With the same new parameters, I did captured the SLUB issue discussed on LKML recently.

3) hackbench_pth.c will fail on ia64 machine because pthread_attr_setstacksize always
fails if the stack size is less than 196*1024. I moved this statement within a __ia64__ check.

This new program could be compiled with command line:
#gcc -g -Wall -o hackbench hackbench.c -lpthread

Thank Ingo for his great comments!

-yanmin

---

/* Test groups of 20 processes spraying to 20 receivers */
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.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;
/*
* 0 means thread mode and others mean process (default)
*/
static unsigned int process_mode = 1;

static int use_pipes = 0;

struct sender_context {
unsigned int num_fds;
int ready_out;
int wakefd;
int out_fds[0];
};

struct receiver_context {
unsigned int num_packets;
int in_fds[2];
int ready_out;
int wakefd;
};

static void barf(const char *msg)
{
fprintf(stderr, "%s (error: %s)\n", msg, strerror(errno));
exit(1);
}

static void print_usage_exit()
{
printf("Usage: hackbench [-pipe] <num groups> [process|thread] [loops]\n");
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(struct sender_context *ctx)
{
char data[DATASIZE];
unsigned int i, j;

ready(ctx->ready_out, ctx->wakefd);

/* Now pump to every receiver. */
for (i = 0; i < loops; i++) {
for (j = 0; j < ctx->num_fds; j++) {
int ret, done = 0;

again:
ret = write(ctx->out_fds[j], data + done, sizeof(data)-done);
if (ret < 0)
barf("SENDER: write");
done += ret;
if (done < sizeof(data))
goto again;
}
}

return NULL;
}

/* One receiver per fd */
static void *receiver(struct receiver_context* ctx)
{
unsigned int i;

if (process_mode)
close(ctx->in_fds[1]);

/* Wait for start... */
ready(ctx->ready_out, ctx->wakefd);

/* Receive them all */
for (i = 0; i < ctx->num_packets; i++) {
char data[DATASIZE];
int ret, done = 0;

again:
ret = read(ctx->in_fds[0], data + done, DATASIZE - done);
if (ret < 0)
barf("SERVER: read");
done += ret;
if (done < DATASIZE)
goto again;
}

return NULL;
}

pthread_t create_worker(void *ctx, void *(*func)(void *))
{
pthread_attr_t attr;
pthread_t childid;
int err;

if (process_mode) {
/* process mode */
/* Fork the receiver. */
switch (fork()) {
case -1: barf("fork()");
case 0:
(*func) (ctx);
exit(0);
}

return (pthread_t) 0;
}

if (pthread_attr_init(&attr) != 0)
barf("pthread_attr_init:");

#ifndef __ia64__
if (pthread_attr_setstacksize(&attr, (size_t)(16*1024)) != 0)
barf("pthread_attr_setstacksize");
#endif

if ((err=pthread_create(&childid, &attr, func, ctx)) != 0) {
fprintf(stderr, "pthread_create failed: %s (%d)\n", strerror(err), err);
exit(-1);
}
return (childid);
}

void reap_worker(pthread_t id)
{
int status;
if (process_mode) {
/* process mode */
wait(&status);
if (!WIFEXITED(status))
exit(1);
} else
pthread_join(id, (void**)&status);
}

/* One group of senders and receivers */
static unsigned int group(pthread_t *pth,
unsigned int num_fds,
int ready_out,
int wakefd)
{
unsigned int i;
struct sender_context* snd_ctx = malloc (sizeof(struct sender_context)
+num_fds*sizeof(int));

for (i = 0; i < num_fds; i++) {
int fds[2];
struct receiver_context* ctx = malloc (sizeof(*ctx));

if (!ctx)
barf("malloc()");

/* Create the pipe between client and server */
fdpair(fds);

ctx->num_packets = num_fds*loops;
ctx->in_fds[0] = fds[0];
ctx->in_fds[1] = fds[1];
ctx->ready_out = ready_out;
ctx->wakefd = wakefd;

pth[i] = create_worker(ctx, (void *)(void *)receiver);

snd_ctx->out_fds[i] = fds[1];
if (process_mode)
close(fds[0]);
}

/* Now we have all the fds, fork the senders */
for (i = 0; i < num_fds; i++) {
snd_ctx->ready_out = ready_out;
snd_ctx->wakefd = wakefd;
snd_ctx->num_fds = num_fds;

pth[num_fds+i] = create_worker(snd_ctx, (void *)(void *)sender);
}

/* Close the fds we have left */
if (process_mode)
for (i = 0; i < num_fds; i++)
close(snd_ctx->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;
pthread_t *pth_tab;

if (argv[1] && strcmp(argv[1], "-pipe") == 0) {
use_pipes = 1;
argc--;
argv++;
}

if (argc < 2 || (num_groups = atoi(argv[1])) == 0)
print_usage_exit();

if (argc > 2) {
if ( !strcmp(argv[2], "process") )
process_mode = 1;
else if ( !strcmp(argv[2], "thread") )
process_mode = 0;
else
print_usage_exit();
}

if (argc > 3)
loops = atoi(argv[3]);

pth_tab = malloc(num_fds * 2 * num_groups * sizeof(pthread_t));

if (!pth_tab)
barf("main:malloc()");

fdpair(readyfds);
fdpair(wakefds);

total_children = 0;
for (i = 0; i < num_groups; i++)
total_children += group(pth_tab+total_children, 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++)
reap_worker(pth_tab[i]);

gettimeofday(&stop, NULL);

/* Print time... */
timersub(&stop, &start, &diff);
printf("Time: %lu.%03lu\n", diff.tv_sec, diff.tv_usec/1000);
exit(0);
}