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