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Test get and set pipe/fifo buffer size.
pipe-size: pipe-size.o
$(CC) $< -o $@
#include <unistd.h>
#include <errno.h>
#include <stdio.h>
// Must use Linux specific fcntl header.
#include </usr/include/linux/fcntl.h>
int main(int argc, char *argv[]) {
if (argc > 2) {
printf("Usage: %s [fifo]\n\n"
"Test get and set pipe buffer size\n",
argv[0]);
return 1;
}
int fd = 0; // Default to stdin, so we can test fcntl over pipe.
if (argc == 2) {
// The specified file should be a fifo.
fd = open(argv[1], O_RDONLY);
if (fd < 0) {
perror("open failed");
return 1;
}
}
long pipe_size = (long)fcntl(fd, F_GETPIPE_SZ);
if (pipe_size == -1) {
perror("get pipe size failed.");
}
printf("default pipe size: %ld\n", pipe_size);
int ret = fcntl(fd, F_SETPIPE_SZ, 1024 * 1024);
if (ret < 0) {
perror("set pipe size failed.");
}
pipe_size = (long)fcntl(fd, F_GETPIPE_SZ);
if (pipe_size == -1) {
perror("get pipe size 2 failed.");
}
printf("new pipe size: %ld\n", pipe_size);
close(fd);
}
#!/bin/bash
echo "Max pipe size for unprivileged user:"
cat /proc/sys/fs/pipe-max-size
echo
echo "Test with pipe"
echo "testdata" | ./pipe-size
echo
echo "Test with fifo"
mkfifo fifo
./pipe-size fifo &
echo "testdata" > fifo
rm fifo

mark!

F_SETPIPE_SZ available since Linux 2.6.35.

http://stackoverflow.com/a/14371183/4896468

czarina commented Mar 29, 2017 edited

Hi,

Thanks for posting this code! I'm running Debian Jessie on my Raspberry Pi and I'd like to set a higher buffer size for my FIFO pipes.

I've increased the max pipe buffer size:
sudo sysctl fs.pipe-max-size=4194304

Testing with a pipe works:

$ echo "testdata" | ./pipe-size
default pipe size: 65536
new pipe size: 1048576

Testing with a fifo produces no errors, but crashes my session:

echo "Test with fifo"
mkfifo fifo
./pipe-size fifo &
echo "testdata" > fifo
default pipe size: 65536
new pipe size: 1048576
Connection to raspberrypi.local closed.

Do you know why this would be?

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