Cyrill Gorcunov wrote:
> 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.
>
+Al. He reworked splice code in 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;
> }
--
Kirill A. Shutemov
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