1 /*-
2 * Copyright (c) 2006, Stephan Uphoff <[email protected]>
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*/
prepareFile(char * filename,int * fdp)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 */
mapBuffer(char ** bufferp,int fd1,int 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
startIO(int fd,char * buffer)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
main(int argc,char * argv[],char * envp[])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