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 https://opensource.org/licenses/CDDL-1.0. 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 /* 28 * Copyright (c) 2013 by Delphix. All rights reserved. 29 */ 30 31 #include <sys/types.h> 32 #include <sys/stat.h> 33 #include <fcntl.h> 34 #include <pthread.h> 35 #include <string.h> 36 #include <stdio.h> 37 #include <unistd.h> 38 #include <stdlib.h> 39 #include <errno.h> 40 41 /* 42 * The size of the output file, "go.out", should be 80*8192*2 = 1310720 43 * 44 * $ cd /tmp; go; ls -l go.out 45 * done. 46 * -rwxr-xr-x 1 jdm staff 1310720 Apr 13 19:45 go.out 47 * $ cd /zfs; go; ls -l go.out 48 * done. 49 * -rwxr-xr-x 1 jdm staff 663552 Apr 13 19:45 go.out 50 * 51 * The file on zfs is short as it does not appear that zfs is making the 52 * implicit seek to EOF and the actual write atomic. From the SUSv3 53 * interface spec, behavior is undefined if concurrent writes are performed 54 * from multi-processes to a single file. So I don't know if this is a 55 * standards violation, but I cannot find any such disclaimers in our 56 * man pages. This issue came up at a customer site in another context, and 57 * the suggestion was to open the file with O_APPEND, but that wouldn't 58 * help with zfs(see 4977529). Also see bug# 5031301. 59 */ 60 61 static int outfd = 0; 62 63 static void * 64 go(void *data) 65 { 66 int ret, i = 0, n = *(int *)data; 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 if (ret != sizeof (buf)) 73 perror("write"); 74 } 75 return (NULL); 76 } 77 78 static void 79 usage(void) 80 { 81 (void) fprintf(stderr, 82 "usage: zfs_threadsappend <file name>\n"); 83 exit(1); 84 } 85 86 int 87 main(int argc, char **argv) 88 { 89 pthread_t tid; 90 int ret = 0; 91 long ncpus = 0; 92 int i; 93 94 if (argc != 2) { 95 usage(); 96 } 97 98 ncpus = sysconf(_SC_NPROCESSORS_ONLN); 99 if (ncpus < 0) { 100 (void) fprintf(stderr, 101 "Invalid return from sysconf(_SC_NPROCESSORS_ONLN)" 102 " : errno (decimal)=%d\n", errno); 103 exit(1); 104 } 105 if (ncpus < 2) { 106 (void) fprintf(stderr, 107 "Must execute this binary on a multi-processor system\n"); 108 exit(1); 109 } 110 111 outfd = open(argv[optind++], O_RDWR|O_CREAT|O_APPEND|O_TRUNC, 0777); 112 if (outfd == -1) { 113 (void) fprintf(stderr, 114 "zfs_threadsappend: " 115 "open(%s, O_RDWR|O_CREAT|O_APPEND|O_TRUNC, 0777)" 116 " failed\n", argv[optind]); 117 perror("open"); 118 exit(1); 119 } 120 121 for (i = 0; i < 2; i++) { 122 ret = pthread_create(&tid, NULL, go, (void *)&i); 123 if (ret != 0) { 124 (void) fprintf(stderr, 125 "zfs_threadsappend: thr_create(#%d) " 126 "failed error=%d\n", i+1, ret); 127 exit(1); 128 } 129 } 130 131 while (pthread_join(tid, NULL) == 0) 132 continue; 133 134 return (0); 135 } 136