测试管道FIFO的大小_linux fifo缓冲区

1.首先创建fifo
linux命令：mkfifo a.fifo
写程序
fifo_size.c：

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

int main()
{
char buf[4096] = {0};
int n, i = 0;
int fd = open(“/a.fifo”, O_RDWR);

printf("time\t\t seq\t write\t total \n");
while (1) {
    int ret = write(fd, buf, sizeof(buf));
    if (ret >= 0)
        n += ret;
    else
        break;

    printf("%u \t%d \t%d \t%d \n", time(NULL), i++, ret, n);
}
return 0;
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}

gcc -o fifo_size fifo_size.c
[hxwang@localhost ~]$ ./fifo_size
time seq write total
1656583502 0 4096 4096
1656583502 1 4096 8192
1656583502 2 4096 12288
1656583502 3 4096 16384
1656583502 4 4096 20480
1656583502 5 4096 24576
1656583502 6 4096 28672
1656583502 7 4096 32768
1656583502 8 4096 36864
1656583502 9 4096 40960
1656583502 10 4096 45056
1656583502 11 4096 49152
1656583502 12 4096 53248
1656583502 13 4096 57344
1656583502 14 4096 61440
1656583502 15 4096 65536
可见fifo最大缓存是65536
写入65536 字节后，写入进程阻塞了
读程序
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
int main(){
char buf[4096] = {0};
int n, i = 0;
int fd = open(“a.fifo”, O_RDWR);
read(fd, buf, 1024);
return 0;
}