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#!/bin/sh
#
# Copyright (c) 2025 Peter Holm <pho@FreeBSD.org>
#
# SPDX-License-Identifier: BSD-2-Clause
#
. ../default.cfg
set -u
prog=$(basename "$0" .sh)
cat > /tmp/$prog.c <<EOF
/* N readers and 1 writer threaded test scenario */
#include <sys/types.h>
#include <sys/mman.h>
#include <assert.h>
#include <err.h>
#include <pthread.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
static int go, n, ps;
static char *cp;
static volatile char v;
void *
rd(void *arg __unused)
{
int i;
while (go == 0)
usleep(100);
while (go == 1) {
for (i = 0; i < n; i += ps) {
v = cp[i];
}
pthread_yield();
}
return(NULL);
}
void
usage(char *prog) {
fprintf(stderr, "Usage: %s <number of threads>\n", prog);
_exit(1);
}
int
main(int argc, char *argv[])
{
pthread_t *tid;
time_t start;
int e, i, nb;
if (argc != 2)
usage(argv[0]);
if (sscanf(argv[1], "%d", &n) != 1)
usage(argv[0]);
if (n > 1)
n--;
if ((tid = calloc(n, sizeof(pthread_t *))) == NULL)
err(1, "calloc()");
ps = getpagesize();
cp = mmap(NULL, n * ps, PROT_READ, MAP_PRIVATE | MAP_ANON, -1, 0);
go = 0;
for (i = 0; i < n; i++) {
if ((e = pthread_create(&tid[i], NULL, rd, NULL)) != 0)
errc(1, e, "pthread_create()");
}
go = 1;
nb = 0;
start = time(NULL);
while (time(NULL) - start < 120) {
for (i = 0; i < n; i += ps) {
if (mprotect(&cp[i], ps, PROT_READ|PROT_WRITE) == -1)
err(1, "mprotect(PROT_READ)");
cp[i] = 1;
if (mprotect(&cp[i], ps, PROT_READ) == -1)
err(1, "mprotect(PROT_READ)");
nb++;
}
}
go = 0;
for (i = 0; i < n; i++) {
if ((e = pthread_join(tid[i], NULL)) != 0)
errc(1, e, "pthread_join() in loop %d", i);
}
if (nb >= 0) {
#if defined(DEBUG)
fprintf(stderr, "%d loops\n", nb);
#endif
;
}
}
EOF
mycc -o /tmp/$prog -Wall -Wextra -O0 /tmp/$prog.c -lpthread || exit 1
/tmp/$prog `sysctl -n hw.ncpu`; s=$?
rm -d /tmp/$prog /tmp/$prog.c
exit $s
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