Hi Xiangxia,
> -----Original Message-----
> From: xiangxia.m....@gmail.com [mailto:xiangxia.m....@gmail.com]
> Sent: Wednesday, March 28, 2018 1:49 PM
> To: Tan, Jianfeng
> Cc: dev@dpdk.org; Tonghao Zhang
> Subject: [PATCH 2/2] vhost: add pipe event for optimizing negotiating
>
> From: Tonghao Zhang <xiangxia.m....@gmail.com>
>
> When vhost—user connects qemu successfully, dpdk will call
Typo: "-"
> the vhost_user_add_connection to add unix socket fd to poll.
> And fdset_add only set the socket fd to a fdentry while poll
> may sleep now. In a general case, this is no problem. But if
> we use hot update for vhost-user, most downtime of VMs network
> is 750+ms. This patch adds pipe event, so after connections are
> ok, dpdk rebuild the poll immediately. With this patch, the
> most downtime is 20~30ms.
>
> Signed-off-by: Tonghao Zhang <xiangxia.m....@gmail.com>
> ---
> lib/librte_vhost/fd_man.c | 49
> +++++++++++++++++++++++++++++++++++++++++++++++
> lib/librte_vhost/fd_man.h | 16 ++++++++++++++++
> lib/librte_vhost/socket.c | 14 ++++++++++++++
> 3 files changed, 79 insertions(+)
>
> diff --git a/lib/librte_vhost/fd_man.c b/lib/librte_vhost/fd_man.c
> index 181711c..7716757 100644
> --- a/lib/librte_vhost/fd_man.c
> +++ b/lib/librte_vhost/fd_man.c
> @@ -15,6 +15,7 @@
> #include <rte_log.h>
>
> #include "fd_man.h"
> +#include "vhost.h"
This is a nice finding and solution, however, I don't think we shall include
vhost header file in fd related files. Actually, I did not find out why you
need to include this header file.
Thanks,
Jianfeng
>
> #define FDPOLLERR (POLLERR | POLLHUP | POLLNVAL)
>
> @@ -272,3 +273,51 @@
>
> return NULL;
> }
> +
> +static void
> +fdset_pipe_read_cb(int readfd, void *dat __rte_unused,
> + int *remove __rte_unused)
> +{
> + char charbuf[16];
> + read(readfd, charbuf, sizeof(charbuf));
> +}
> +
> +void
> +fdset_pipe_uninit(struct fdset *fdset)
> +{
> + fdset_del(fdset, fdset->u.readfd);
> + close(fdset->u.readfd);
> + close(fdset->u.writefd);
> +}
> +
> +int
> +fdset_pipe_init(struct fdset *fdset)
> +{
> + int ret;
> +
> + if (pipe(fdset->u.pipefd) < 0) {
> + RTE_LOG(ERR, VHOST_CONFIG,
> + "failed to create pipe for vhost fdset\n");
> + return -1;
> + }
> +
> + ret = fdset_add(fdset, fdset->u.readfd,
> + fdset_pipe_read_cb, NULL, NULL);
> +
> + if (ret < 0) {
> + RTE_LOG(ERR, VHOST_CONFIG,
> + "failed to add pipe readfd %d into vhost server
> fdset\n",
> + fdset->u.readfd);
> +
> + fdset_pipe_uninit(fdset);
> + return -1;
> + }
> +
> + return 0;
> +}
> +
> +void
> +fdset_pipe_notify(struct fdset *fdset)
> +{
> + write(fdset->u.writefd, "1", 1);
> +}
> diff --git a/lib/librte_vhost/fd_man.h b/lib/librte_vhost/fd_man.h
> index 3a9276c..76a42fb 100644
> --- a/lib/librte_vhost/fd_man.h
> +++ b/lib/librte_vhost/fd_man.h
> @@ -25,6 +25,16 @@ struct fdset {
> struct fdentry fd[MAX_FDS];
> pthread_mutex_t fd_mutex;
> int num; /* current fd number of this fdset */
> +
> + union pipefds {
> + struct {
> + int pipefd[2];
> + };
> + struct {
> + int readfd;
> + int writefd;
> + };
> + } u;
> };
>
>
> @@ -37,4 +47,10 @@ int fdset_add(struct fdset *pfdset, int fd,
>
> void *fdset_event_dispatch(void *arg);
>
> +int fdset_pipe_init(struct fdset *fdset);
> +
> +void fdset_pipe_uninit(struct fdset *fdset);
> +
> +void fdset_pipe_notify(struct fdset *fdset);
> +
> #endif
> diff --git a/lib/librte_vhost/socket.c b/lib/librte_vhost/socket.c
> index 95bed78..795239c 100644
> --- a/lib/librte_vhost/socket.c
> +++ b/lib/librte_vhost/socket.c
> @@ -231,6 +231,8 @@ struct vhost_user {
> pthread_mutex_lock(&vsocket->conn_mutex);
> TAILQ_INSERT_TAIL(&vsocket->conn_list, conn, next);
> pthread_mutex_unlock(&vsocket->conn_mutex);
> +
> + fdset_pipe_notify(&vhost_user.fdset);
> return;
>
> err:
> @@ -829,11 +831,23 @@ struct vhost_device_ops const *
> return -1;
>
> if (fdset_tid == 0) {
> + /**
> + * create a pipe which will be waited by poll and notified to
> + * rebuild the wait list of poll.
> + */
> + if (fdset_pipe_init(&vhost_user.fdset) < 0) {
> + RTE_LOG(ERR, VHOST_CONFIG,
> + "failed to create pipe for vhost fdset\n");
> + return -1;
> + }
> +
> int ret = pthread_create(&fdset_tid, NULL, fdset_event_dispatch,
> &vhost_user.fdset);
> if (ret != 0) {
> RTE_LOG(ERR, VHOST_CONFIG,
> "failed to create fdset handling thread");
> +
> + fdset_pipe_uninit(&vhost_user.fdset);
> return -1;
> } else {
> snprintf(thread_name, RTE_MAX_THREAD_NAME_LEN,
> --
> 1.8.3.1
