1 /*- 2 * Copyright (c) 2006, Stephan Uphoff <ups@freebsd.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice unmodified, this list of conditions, and the following 10 * disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 * 26 * $FreeBSD$ 27 */ 28 29 30 #include <sys/types.h> 31 #include <unistd.h> 32 #include <sys/stat.h> 33 #include <fcntl.h> 34 #include <stdio.h> 35 #include <sys/mman.h> 36 37 38 int prepareFile(char* filename,int* fdp); 39 int mapBuffer(char** bufferp,int fd1,int fd2); 40 int startIO(int fd,char *buffer); 41 42 int pagesize; 43 44 #define FILESIZE (32*1024) 45 char wbuffer[FILESIZE]; 46 47 /* Create a FILESIZE sized file - then remove file data from the cache*/ 48 int prepareFile(char* filename,int* fdp) 49 { 50 int fd; 51 int len; 52 int status; 53 void *addr; 54 55 fd = open(filename,O_CREAT | O_TRUNC | O_RDWR,S_IRWXU); 56 if (fd == -1) 57 { 58 perror("Creating file"); 59 return fd; 60 } 61 62 len = write(fd,wbuffer,FILESIZE); 63 if (len < 0) 64 { 65 perror("Write failed"); 66 return 1; 67 } 68 69 status = fsync(fd); 70 if (status != 0) 71 { 72 perror("fsync failed"); 73 return 1; 74 } 75 76 addr = mmap(NULL,FILESIZE, PROT_READ | PROT_WRITE , MAP_SHARED, fd, 0); 77 if (addr == MAP_FAILED) 78 { 79 perror("Mmap failed"); 80 return 1; 81 } 82 83 status = msync(addr,FILESIZE,MS_INVALIDATE | MS_SYNC); 84 if (status != 0) 85 { 86 perror("Msync failed"); 87 return 1; 88 } 89 90 munmap(addr,FILESIZE); 91 92 *fdp = fd; 93 return 0; 94 } 95 96 97 /* mmap a 2 page buffer - first page is from fd1, second page from fd2 */ 98 int mapBuffer(char** bufferp,int fd1,int fd2) 99 { 100 void* addr; 101 char *buffer; 102 103 addr = mmap(NULL,pagesize*2, PROT_READ | PROT_WRITE , MAP_SHARED, fd1, 0); 104 if (addr == MAP_FAILED) 105 { 106 perror("Mmap failed"); 107 return 1; 108 } 109 110 buffer = addr; 111 addr = mmap(buffer + pagesize,pagesize, PROT_READ | PROT_WRITE , MAP_FIXED | 112 MAP_SHARED, fd2, 0); 113 114 if (addr == MAP_FAILED) 115 { 116 perror("Mmap2 failed"); 117 return 1; 118 } 119 *bufferp = buffer; 120 return 0; 121 } 122 123 124 int startIO(int fd,char *buffer) 125 { 126 ssize_t len; 127 len = write(fd,buffer,2*pagesize); 128 if (len == -1) 129 { 130 perror("write failed"); 131 return 1; 132 } 133 return 0; 134 } 135 136 137 int main(int argc,char *argv[],char *envp[]) 138 { 139 140 int fdA,fdB,fdDelayA,fdDelayB; 141 int status; 142 char *bufferA,*bufferB; 143 pid_t pid; 144 145 pagesize = getpagesize(); 146 147 if ((prepareFile("A",&fdA)) 148 || (prepareFile("B",&fdB)) 149 || (prepareFile("DelayA",&fdDelayA)) 150 || (prepareFile("DelayB",&fdDelayB)) 151 || (mapBuffer(&bufferA,fdDelayA,fdB)) 152 || (mapBuffer(&bufferB,fdDelayB,fdA))) 153 exit(1); 154 155 pid = fork(); 156 157 if (pid == 0) 158 { 159 status = startIO(fdA,bufferA); 160 exit(status); 161 } 162 163 if (pid == -1) 164 { 165 exit(1); 166 } 167 status = startIO(fdB,bufferB); 168 exit(status); 169 170 } 171 172 173 174 175 176