Il 21/11/2013 10:11, Lei Li ha scritto:
> This patch implements save_page callback for the outside
> of page flipping. It will write the address of the page
> on the Unix socket and flip the page data on pipe by
> vmsplice(). Every page address would have a header flag
> RAM_SAVE_FLAG_HOOK, which will trigger the load hook to
> receive it in incoming side as well.
>
> Signed-off-by: Lei Li <[email protected]>
> ---
> migration-local.c | 54
> +++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 files changed, 54 insertions(+), 0 deletions(-)
>
> diff --git a/migration-local.c b/migration-local.c
> index 0f0896b..14207e9 100644
> --- a/migration-local.c
> +++ b/migration-local.c
> @@ -200,6 +200,59 @@ static int qemu_local_send_pipefd(QEMUFile *f, void
> *opaque,
> return 0;
> }
>
> +static size_t qemu_local_save_ram(QEMUFile *f, void *opaque,
> + MemoryRegion *mr, ram_addr_t offset,
> + size_t size, int *bytes_sent)
> +{
> + QEMUFileLocal *s = opaque;
> + ram_addr_t current_addr = mr->ram_addr + offset;
> + void *ram_addr;
> + ssize_t ret;
> +
> + if (s->unix_page_flipping) {
> + qemu_fflush(s->file);
> + qemu_put_be64(s->file, RAM_SAVE_FLAG_HOOK);
> +
> + /* Write page address to unix socket */
> + qemu_put_be64(s->file, current_addr);
> +
You can write current_addr | RAM_SAVE_FLAG_HOOK. The value will be in
the flags argument of the hook_ram_load, you can extract it with "flags
& ~RAM_SAVE_FLAG_HOOK". This cuts by half the data written to the Unix
socket.
Paolo
> + ram_addr = memory_region_get_ram_ptr(mr) + offset;
> +
> + /* vmsplice page data to pipe */
> + struct iovec iov = {
> + .iov_base = ram_addr,
> + .iov_len = size,
> + };
> +
> + /*
> + * The flag SPLICE_F_MOVE is introduced in kernel for the page
> + * flipping feature in QEMU, which will movie pages rather than
> + * copying, previously unused.
> + *
> + * If a move is not possible the kernel will transparently falls
> + * back to copying data.
> + *
> + * For older kernels the SPLICE_F_MOVE would be ignored and a copy
> + * would occur.
> + */
> + ret = vmsplice(s->pipefd[1], &iov, 1, SPLICE_F_GIFT | SPLICE_F_MOVE);
> + if (ret == -1) {
> + if (errno != EAGAIN && errno != EINTR) {
> + fprintf(stderr, "vmsplice save error: %s\n",
> strerror(errno));
> + return ret;
> + }
> + } else {
> + if (bytes_sent) {
> + *bytes_sent = 1;
> + }
> + DPRINTF("block_offset: %lu, offset: %lu\n", block_offset,
> offset);
> + return 0;
> + }
> + }
> +
> + return RAM_SAVE_CONTROL_NOT_SUPP;
> +}
> +
> static const QEMUFileOps pipe_read_ops = {
> .get_fd = qemu_local_get_sockfd,
> .get_buffer = qemu_local_get_buffer,
> @@ -211,6 +264,7 @@ static const QEMUFileOps pipe_write_ops = {
> .writev_buffer = qemu_local_writev_buffer,
> .close = qemu_local_close,
> .before_ram_iterate = qemu_local_send_pipefd,
> + .save_page = qemu_local_save_ram
> };
>
> QEMUFile *qemu_fopen_socket_local(int sockfd, const char *mode)
>
