[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH 12/17] migration-local: override hook_ram_load
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH 12/17] migration-local: override hook_ram_load |
Date: |
Thu, 24 Oct 2013 15:06:36 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130923 Thunderbird/17.0.9 |
Il 22/10/2013 04:25, Lei Li ha scritto:
> Override hook_ram_load to receive the pipe file descriptor
> passed by source process and page address which will be
> extracted to vmsplice the page data from pipe.
>
> Signed-off-by: Lei Li <address@hidden>
> ---
> migration-local.c | 85
> +++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 files changed, 85 insertions(+), 0 deletions(-)
>
> diff --git a/migration-local.c b/migration-local.c
> index 7ccec30..083a24f 100644
> --- a/migration-local.c
> +++ b/migration-local.c
> @@ -32,6 +32,8 @@
> #include "trace.h"
> #include "qemu/osdep.h"
>
> +#define BEFORE_PIPE_FD 199
> +
> //#define DEBUG_MIGRATION_LOCAL
>
> #ifdef DEBUG_MIGRATION_LOCAL
> @@ -50,6 +52,8 @@ typedef struct QEMUFileLocal {
> bool unix_page_flipping;
> } QEMUFileLocal;
>
> +static bool pipefd_passed;
> +
> static int qemu_local_get_sockfd(void *opaque)
> {
> QEMUFileLocal *s = opaque;
> @@ -64,6 +68,22 @@ static int qemu_local_get_buffer(void *opaque, uint8_t
> *buf,
> ssize_t len;
>
> for (;;) {
> + /*
> + * FIX ME: BEFORE_PIPE_FD is hard-coded and checked temporarily here
> + * because that the control message of passed pipe file descriptor
> + * might be 'eaten' to stream file by qemu_recv(), which would lead
> + * to the failure of recv_pipefd(), as it should stay in the socket
> + * and received by the real receiver recvmsg().
> + *
> + * Although this message is followed by the first load_hook flags
> + * RAM_SAVE_FLAG_HOOK, the incoming side is hardly to avoid this
> + * as it would fill it into the stream file before any check action
> + * taken. Need to find a way out to fix this.
> + */
> + if (size > BEFORE_PIPE_FD && !pipefd_passed) {
> + size = BEFORE_PIPE_FD;
> + }
I think you can simply use recvmsg always, or at least until !pipefd_passed.
> len = qemu_recv(s->sockfd, buf, size, 0);
> if (len != -1) {
> break;
> @@ -115,6 +135,7 @@ static int qemu_local_close(void *opaque)
> }
>
> static int send_pipefd(int sockfd, int pipefd);
> +static int recv_pipefd(int sockfd);
>
> static int qemu_local_send_pipefd(QEMUFile *f, void *opaque,
> uint64_t flags)
> @@ -192,10 +213,74 @@ static size_t qemu_local_save_ram(QEMUFile *f, void
> *opaque,
> return RAM_SAVE_CONTROL_NOT_SUPP;
> }
>
> +static int qemu_local_ram_load(QEMUFile *f, void *opaque,
> + uint64_t flags)
> +{
> + QEMUFileLocal *s = opaque;
> + ram_addr_t addr;
> + struct iovec iov;
> + ssize_t ret;
> +
> + /* Receive the pipe file descripter passed from source process */
> + if (!pipefd_passed) {
> + s->pipefd[0] = recv_pipefd(s->sockfd);
> + if (s->pipefd[0] <= 0) {
> + fprintf(stderr, "failed to receive pipe fd: %d\n", s->pipefd[0]);
> + } else {
> + pipefd_passed = 1;
> + DPRINTF(stderr, "succeed\n");
> + }
> +
> + return s->pipefd[0];
> + }
> +
> + if (pipefd_passed) {
> + void *host;
> +
> + /*
> + * Extract the page address from the 8-byte record and
> + * read the page data from the pipe.
> + */
> + addr = qemu_get_be64(s->file);
> + host = qemu_get_ram_ptr(addr);
> +
> + iov.iov_base = host;
> + iov.iov_len = TARGET_PAGE_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[0], &iov, 1, SPLICE_F_MOVE);
> + if (ret == -1) {
> + if (errno != EAGAIN && errno != EINTR) {
> + fprintf(stderr, "vmsplice() load error: %s",
> strerror(errno));
> + return ret;
> + }
> + DPRINTF("vmsplice load error\n");
> + } else if (ret == 0) {
> + DPRINTF(stderr, "load_page: zero read\n");
> + }
> +
> + DPRINTF("vmsplice (read): %zu\n", ret);
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +
> static const QEMUFileOps pipe_read_ops = {
> .get_fd = qemu_local_get_sockfd,
> .get_buffer = qemu_local_get_buffer,
> .close = qemu_local_close,
> + .hook_ram_load = qemu_local_ram_load
> };
>
> static const QEMUFileOps pipe_write_ops = {
> -- 1.7.7.6
>
Otherwise looks good,
Paolo
- [Qemu-devel] [PATCH 06/17] migration-local: introduce qemu_fopen_socket_local(), (continued)
- [Qemu-devel] [PATCH 06/17] migration-local: introduce qemu_fopen_socket_local(), Lei Li, 2013/10/21
- [Qemu-devel] [PATCH 07/17] migration-local: add send_pipefd(), Lei Li, 2013/10/21
- [Qemu-devel] [PATCH 08/17] migration-local: add recv_pipefd(), Lei Li, 2013/10/21
- [Qemu-devel] [PATCH 09/17] migration-local: override before_ram_iterate to send pipefd, Lei Li, 2013/10/21
- [Qemu-devel] [PATCH 10/17] migration-local: override save_page for page transmit, Lei Li, 2013/10/21
- [Qemu-devel] [PATCH 11/17] savevm: adjust ram_control_save_page for page flipping, Lei Li, 2013/10/21
- [Qemu-devel] [PATCH 12/17] migration-local: override hook_ram_load, Lei Li, 2013/10/21
- Re: [Qemu-devel] [PATCH 12/17] migration-local: override hook_ram_load,
Paolo Bonzini <=
- [Qemu-devel] [PATCH 13/17] migration-unix: replace qemu_fopen_socket with qemu_fopen_socket_local, Lei Li, 2013/10/21
- [Qemu-devel] [PATCH 14/17] add new RanState RAN_STATE_FLIPPING_MIGRATE, Lei Li, 2013/10/21
- Re: [Qemu-devel] [PATCH 14/17] add new RanState RAN_STATE_FLIPPING_MIGRATE, Paolo Bonzini, 2013/10/24
- Re: [Qemu-devel] [PATCH 14/17] add new RanState RAN_STATE_FLIPPING_MIGRATE, Paolo Bonzini, 2013/10/24