177 lines
3.9 KiB
C
177 lines
3.9 KiB
C
/*-
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* Copyright (c) 2006, Stephan Uphoff <ups@freebsd.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice unmodified, this list of conditions, and the following
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* disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <sys/types.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/mman.h>
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int prepareFile(const char* filename,int* fdp);
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int mapBuffer(char** bufferp,int fd1,int fd2);
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int startIO(int fd,char *buffer);
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static int pagesize;
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#define FILESIZE (32*1024)
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static char wbuffer[FILESIZE];
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/* Create a FILESIZE sized file - then remove file data from the cache*/
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int prepareFile(const char* filename,int* fdp)
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{
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int fd;
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int len;
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int status;
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void *addr;
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fd = open(filename,O_CREAT | O_TRUNC | O_RDWR,S_IRWXU);
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if (fd == -1)
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{
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perror("Creating file");
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return fd;
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}
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len = write(fd,wbuffer,FILESIZE);
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if (len < 0)
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{
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perror("Write failed");
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return 1;
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}
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status = fsync(fd);
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if (status != 0)
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{
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perror("fsync failed");
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return 1;
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}
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addr = mmap(NULL,FILESIZE, PROT_READ | PROT_WRITE , MAP_SHARED, fd, 0);
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if (addr == MAP_FAILED)
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{
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perror("Mmap failed");
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return 1;
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}
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status = msync(addr,FILESIZE,MS_INVALIDATE | MS_SYNC);
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if (status != 0)
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{
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perror("Msync failed");
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return 1;
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}
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munmap(addr,FILESIZE);
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*fdp = fd;
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return 0;
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}
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/* mmap a 2 page buffer - first page is from fd1, second page from fd2 */
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int mapBuffer(char** bufferp,int fd1,int fd2)
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{
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void* addr;
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char *buffer;
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addr = mmap(NULL,pagesize*2, PROT_READ | PROT_WRITE , MAP_SHARED, fd1, 0);
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if (addr == MAP_FAILED)
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{
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perror("Mmap failed");
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return 1;
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}
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buffer = addr;
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addr = mmap(buffer + pagesize,pagesize, PROT_READ | PROT_WRITE , MAP_FIXED |
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MAP_SHARED, fd2, 0);
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if (addr == MAP_FAILED)
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{
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perror("Mmap2 failed");
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return 1;
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}
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*bufferp = buffer;
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return 0;
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}
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int startIO(int fd,char *buffer)
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{
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ssize_t len;
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len = write(fd,buffer,2*pagesize);
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if (len == -1)
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{
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perror("write failed");
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return 1;
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}
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return 0;
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}
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int main(int argc __unused, char *argv[] __unused)
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{
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int fdA,fdB,fdDelayA,fdDelayB;
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int status;
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char *bufferA,*bufferB;
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pid_t pid;
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pagesize = getpagesize();
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if ((prepareFile("A",&fdA))
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|| (prepareFile("B",&fdB))
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|| (prepareFile("DelayA",&fdDelayA))
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|| (prepareFile("DelayB",&fdDelayB))
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|| (mapBuffer(&bufferA,fdDelayA,fdB))
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|| (mapBuffer(&bufferB,fdDelayB,fdA)))
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exit(1);
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pid = fork();
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if (pid == 0)
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{
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status = startIO(fdA,bufferA);
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exit(status);
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}
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if (pid == -1)
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{
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exit(1);
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}
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status = startIO(fdB,bufferB);
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exit(status);
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}
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