tcp multi-accept benchmark

.gitignore

/accept-server
/accept-client
*.o

accept-client.c

#include "sampler.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <sys/un.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <unistd.h>
#include <time.h>

static void child(void)
{
  struct sampler sampler = SAMPLER_INIT(1000);
  struct sockaddr_in sa = {
    .sin_family = AF_INET,
    .sin_port = htons(42424),
    .sin_addr = htonl(INADDR_LOOPBACK),
  };

  for (;;) {
    sampler_start(&sampler);
    {
      int fd = socket(AF_INET, SOCK_STREAM, 0);
      if (fd == -1) {
        perror("socket");
        exit(1);
      }

      if (connect(fd, (const struct sockaddr *) &sa, sizeof(sa))) {
        perror("connect");
        exit(1);
      }

      struct linger linger = { .l_onoff = 1, .l_linger = 1 };
      setsockopt(fd, SOL_SOCKET, SO_LINGER, &linger, sizeof(linger));
      close(fd);
    }
    sampler_stop(&sampler);
  }
}

int main(int argc, char **argv)
{
  int nforks;
  int i;

  nforks = argc > 1 ? atoi(argv[1]) : 0;
  if (nforks == 0)
    nforks = 2;

  for (i = 0; i < nforks; i++) {
    pid_t pid = fork();
    if (pid == -1)
      perror("fork");
    if (pid == 0)
      child();
  }

  for (i = 0; i < nforks; i++) {
    int status;
    wait(&status);
  }

  return 0;
}

accept-server.c

#include "sampler.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <sys/un.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <unistd.h>
#include <time.h>
#include <poll.h>

static void child(int fd, int backoff)
{
  struct sampler sampler = SAMPLER_INIT(1000);

  for (;;) {
    struct pollfd pfd = { .fd = fd, .events = POLLIN };
    if (poll(&pfd, 1, -1) == -1) {
      perror("poll");
      continue;
    }

    sampler_start(&sampler);
    {
      int peerfd = accept(fd, NULL, NULL);
      if (peerfd == -1)
        perror("accept");
      else {
        struct linger linger = { .l_onoff = 1, .l_linger = 1 };
        setsockopt(fd, SOL_SOCKET, SO_LINGER, &linger, sizeof(linger));
        close(peerfd);
      }

      if (backoff) {
        struct timespec timeout = { 0, 1 };
        nanosleep(&timeout, NULL);
      }
    }
    sampler_stop(&sampler);
  }
}

int main(int argc, char **argv)
{
  int i;

  int nforks = argc > 1 ? atoi(argv[1]) : 0;
  if (nforks == 0)
    nforks = 2;

  int backoff = argc > 2 ? atoi(argv[2]) : 0;

  int fd = socket(AF_INET, SOCK_STREAM, 0);
  if (fd == -1) {
    perror("socket");
    exit(1);
  }

  int on = 1;
  setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));

  struct sockaddr_in sa = {
    .sin_family = AF_INET,
    .sin_port = htons(42424),
    .sin_addr = htonl(INADDR_LOOPBACK),
  };

  if (bind(fd, (const struct sockaddr *) &sa, sizeof(sa))) {
    perror("bind");
    exit(1);
  }

  if (listen(fd, 1024)) {
    perror("listen");
    exit(1);
  }

  for (i = 0; i < nforks; i++) {
    pid_t pid = fork();
    if (pid == -1)
      perror("fork");
    if (pid == 0)
      child(fd, backoff);
  }

  close(fd);

  for (i = 0; i < nforks; i++) {
    int status;
    wait(&status);
  }

  return 0;
}

Makefile

override CFLAGS += -D_GNU_SOURCE
override LDFLAGS += -lrt

.PHONY:	all clean

all:	accept-server accept-client

clean:
	$(RM) accept-server accept-client *.o

accept-client:	accept-client.o
	$(CC) $^ -o $@ $(LDFLAGS)

accept-server:	accept-server.o
	$(CC) $^ -o $@ $(LDFLAGS)

accept-client.o:	accept-client.c sampler.h
accept-server.o:	accept-server.c sampler.h

sampler.h

#ifndef _SAMPLER_H_
#define _SAMPLER_H_

#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <unistd.h>
#include <sched.h>
#include <time.h>

#define SAMPLER_INIT(size_) { .start = now(), .size = (size_), .min = (u64) -1 }

typedef uint64_t u64;

struct sampler
{
  unsigned size;
  unsigned count;
  u64 start;
  u64 avg;
  u64 min;
  u64 max;
  u64 ts;
};

static u64 now(void)
{
  struct timespec ts;
  clock_gettime(CLOCK_MONOTONIC, &ts);
  return ts.tv_sec * (u64) 1e9 + ts.tv_nsec;
}

static void sampler_start(struct sampler *s)
{
  s->ts = now();
}

static void sampler_stop(struct sampler *s)
{
  u64 ts = now() - s->ts;
  u64 avg = s->avg * s->count;

  s->count += 1;
  s->avg = (avg + ts) / s->count;

  if (s->count >= s->size) {
    u64 total = now() - s->start;
    printf("pid=%d cpu=%d avg=%.1fus min=%.1fus max=%.1fus\ttotal=%.1fms\n",
           getpid(),
           sched_getcpu(),
           s->avg / 1e3,
           s->min / 1e3,
           s->max / 1e3,
           total / 1e6);
    struct sampler blank = SAMPLER_INIT(s->size);
    *s = blank;
  } else {
    if (s->min > ts) s->min = ts;
    if (s->max < ts) s->max = ts;
  }
}

#endif /* _SAMPLER_H_ */