1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 * $FreeBSD$ 21 */ 22 23 /* 24 * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 25 * Use is subject to license terms. 26 */ 27 28 #pragma ident "@(#)threadsappend.c 1.3 07/05/25 SMI" 29 30 #include <sys/types.h> 31 #include <sys/stat.h> 32 #include <fcntl.h> 33 #include <pthread.h> 34 #include <string.h> 35 #include <stdio.h> 36 #include <unistd.h> 37 #include <stdlib.h> 38 #include <errno.h> 39 40 /* 41 * The size of the output file, "go.out", should be 80*8192*2 = 1310720 42 * 43 * $ cd /tmp; go; ls -l go.out 44 * done. 45 * -rwxr-xr-x 1 jdm staff 1310720 Apr 13 19:45 go.out 46 * $ cd /zfs; go; ls -l go.out 47 * done. 48 * -rwxr-xr-x 1 jdm staff 663552 Apr 13 19:45 go.out 49 * 50 * The file on zfs is short as it does not appear that zfs is making the 51 * implicit seek to EOF and the actual write atomic. From the SUSv3 52 * interface spec, behavior is undefined if concurrent writes are performed 53 * from multi-processes to a single file. So I don't know if this is a 54 * standards violation, but I cannot find any such disclaimers in our 55 * man pages. This issue came up at a customer site in another context, and 56 * the suggestion was to open the file with O_APPEND, but that wouldn't 57 * help with zfs(see 4977529). Also see bug# 5031301. 58 */ 59 60 static int outfd = 0; 61 62 static void * 63 go(void *data) 64 { 65 int i = 0, n = *(int *)data; 66 ssize_t ret = 0; 67 char buf[8192] = {0}; 68 (void) memset(buf, n, sizeof (buf)); 69 70 for (i = 0; i < 80; i++) { 71 ret = write(outfd, buf, sizeof (buf)); 72 } 73 return (NULL); 74 } 75 76 static void 77 usage() 78 { 79 (void) fprintf(stderr, 80 "usage: zfs_threadsappend <file name>\n"); 81 exit(1); 82 } 83 84 int 85 main(int argc, char **argv) 86 { 87 pthread_t threads[2]; 88 int ret = 0; 89 long ncpus = 0; 90 int i; 91 92 if (argc != 2) { 93 usage(); 94 } 95 96 ncpus = sysconf(_SC_NPROCESSORS_ONLN); 97 if (ncpus < 0) { 98 (void) fprintf(stderr, 99 "Invalid return from sysconf(_SC_NPROCESSORS_ONLN)" 100 " : errno (decimal)=%d\n", errno); 101 exit(1); 102 } 103 if (ncpus < 2) { 104 (void) fprintf(stderr, 105 "Must execute this binary on a multi-processor system\n"); 106 exit(1); 107 } 108 109 outfd = open(argv[optind++], O_RDWR|O_CREAT|O_APPEND|O_TRUNC, 0777); 110 if (outfd == -1) { 111 (void) fprintf(stderr, 112 "zfs_threadsappend: " 113 "open(%s, O_RDWR|O_CREAT|O_APPEND|O_TRUNC, 0777)" 114 " failed\n", argv[optind]); 115 perror("open"); 116 exit(1); 117 } 118 119 for (i = 0; i < 2; i++) { 120 ret = pthread_create(&threads[i], NULL, go, (void *)&i); 121 if (ret != 0) { 122 (void) fprintf(stderr, 123 "zfs_threadsappend: thr_create(#%d) " 124 "failed error=%d\n", i+1, ret); 125 exit(1); 126 } 127 } 128 129 for (i = 0; i < 2; i++) { 130 if (pthread_join(threads[i], NULL) != 0) 131 break; 132 } 133 134 return (0); 135 } 136