Hi! While been trying to run criu on linux-next (due to recent Kirill's patch
related
to /proc/pid/clear_refs with THP enabled) I noticed that it fails dumping
programs when
moves data from memory pages into an image file. So I wrote pretty idiotic test
and
run it on current fedora 20 kernel and then on linux-next.
fedora-20 output
----------------
[cyrill@moon criu] ~/pipe
Opened pipe-test.SQBcJa
vmspliced 8192 bytes
spliced 4096 bytes
linux-next
----------
[root@fc criu]# ~/pipe
Opened pipe-test.9nZSW7
vmspliced 8192 bytes
spliced 8192 bytes
In test I fill pipe with 8K data then splice 4K of it into a file (the test
is below). Is it intended, or I did some silly mistake?
---
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <sys/uio.h>
#define ARRAY_SIZE(x) (sizeof(x)/sizeof(x[0]))
static char buf[8 << 20];
int main(int argc, char *argv[])
{
char *tmpname, t[64] = "pipe-test.XXXXXX";
int _pipe[2], fd, ret = 0;
struct iovec iov[] = {
[0] = {
.iov_base = &buf[0],
.iov_len = 4096,
},
[1] = {
.iov_base = &buf[4096],
.iov_len = 4096,
},
};
if (pipe(_pipe)) {
perror("Can't create pipe");
exit(1);
}
memset(buf, 0x1, sizeof(buf));
tmpname = mktemp(t);
fd = open(tmpname, O_RDWR | O_CREAT | O_TRUNC);
if (fd < 0) {
perror("Can't open temp file");
close(_pipe[0]);
close(_pipe[1]);
exit(1);
}
printf("Opened %s\n", tmpname);
ret = vmsplice(_pipe[1], iov, ARRAY_SIZE(iov), SPLICE_F_GIFT);
printf("vmspliced %li bytes\n", (long)ret);
ret = splice(_pipe[0], NULL, fd, NULL, iov[0].iov_len, SPLICE_F_MOVE);
printf("spliced %li bytes\n", (long)ret);
out:
close(_pipe[0]);
close(_pipe[1]);
close(fd);
unlink(tmpname);
return ret;
}
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