Re: [Qemu-devel] [PATCH 04/14] migration: let incoming side use thread context

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Peter Xu (peterx@redhat.com) wrote:
> The old incoming migration is running in main thread and default
> gcontext.  With the new qio_channel_add_watch_full() we can now let it
> run in the thread's own gcontext (if there is one).
> 
> Currently this patch does nothing alone.  But when any of the incoming
> migration is run in another iothread (e.g., the upcoming migrate-recover
> command), this patch will bind the incoming logic to the iothread
> instead of the main thread (which may already get page faulted and
> hanged).

Does this make any difference to the Postcopy listener thread, which
takes over reading from the main thread once in postcopy mode?
(See savevm.c:postcopy_ram_listen_thread).

Dave

> RDMA is not considered for now since it's not even using the QIO APIs at
> all.
> 
> CC: Juan Quintela <quintela@redhat.com>
> CC: Dr. David Alan Gilbert <dgilbert@redhat.com>
> CC: Laurent Vivier <lvivier@redhat.com>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
>  migration/exec.c   | 11 ++++++-----
>  migration/fd.c     | 11 ++++++-----
>  migration/socket.c | 12 +++++++-----
>  3 files changed, 19 insertions(+), 15 deletions(-)
> 
> diff --git a/migration/exec.c b/migration/exec.c
> index 0bc5a427dd..f401fc005e 100644
> --- a/migration/exec.c
> +++ b/migration/exec.c
> @@ -55,6 +55,7 @@ void exec_start_incoming_migration(const char *command, Error **errp)
>  {
>      QIOChannel *ioc;
>      const char *argv[] = { "/bin/sh", "-c", command, NULL };
> +    GSource *source;
>  
>      trace_migration_exec_incoming(command);
>      ioc = QIO_CHANNEL(qio_channel_command_new_spawn(argv,
> @@ -65,9 +66,9 @@ void exec_start_incoming_migration(const char *command, Error **errp)
>      }
>  
>      qio_channel_set_name(ioc, "migration-exec-incoming");
> -    qio_channel_add_watch(ioc,
> -                          G_IO_IN,
> -                          exec_accept_incoming_migration,
> -                          NULL,
> -                          NULL);
> +    source = qio_channel_add_watch_full(ioc, G_IO_IN,
> +                                        exec_accept_incoming_migration,
> +                                        NULL, NULL,
> +                                        g_main_context_get_thread_default());
> +    g_source_unref(source);
>  }
> diff --git a/migration/fd.c b/migration/fd.c
> index cd06182d1e..9c593eb3ff 100644
> --- a/migration/fd.c
> +++ b/migration/fd.c
> @@ -55,6 +55,7 @@ void fd_start_incoming_migration(const char *infd, Error **errp)
>  {
>      QIOChannel *ioc;
>      int fd;
> +    GSource *source;
>  
>      fd = strtol(infd, NULL, 0);
>      trace_migration_fd_incoming(fd);
> @@ -66,9 +67,9 @@ void fd_start_incoming_migration(const char *infd, Error **errp)
>      }
>  
>      qio_channel_set_name(QIO_CHANNEL(ioc), "migration-fd-incoming");
> -    qio_channel_add_watch(ioc,
> -                          G_IO_IN,
> -                          fd_accept_incoming_migration,
> -                          NULL,
> -                          NULL);
> +    source = qio_channel_add_watch_full(ioc, G_IO_IN,
> +                                        fd_accept_incoming_migration,
> +                                        NULL, NULL,
> +                                        g_main_context_get_thread_default());
> +    g_source_unref(source);
>  }
> diff --git a/migration/socket.c b/migration/socket.c
> index e090097077..82c330083c 100644
> --- a/migration/socket.c
> +++ b/migration/socket.c
> @@ -164,6 +164,7 @@ static void socket_start_incoming_migration(SocketAddress *saddr,
>                                              Error **errp)
>  {
>      QIOChannelSocket *listen_ioc = qio_channel_socket_new();
> +    GSource *source;
>  
>      qio_channel_set_name(QIO_CHANNEL(listen_ioc),
>                           "migration-socket-listener");
> @@ -173,11 +174,12 @@ static void socket_start_incoming_migration(SocketAddress *saddr,
>          return;
>      }
>  
> -    qio_channel_add_watch(QIO_CHANNEL(listen_ioc),
> -                          G_IO_IN,
> -                          socket_accept_incoming_migration,
> -                          listen_ioc,
> -                          (GDestroyNotify)object_unref);
> +    source = qio_channel_add_watch_full(QIO_CHANNEL(listen_ioc), G_IO_IN,
> +                                        socket_accept_incoming_migration,
> +                                        listen_ioc,
> +                                        (GDestroyNotify)object_unref,
> +                                        g_main_context_get_thread_default());
> +    g_source_unref(source);
>  }
>  
>  void tcp_start_incoming_migration(const char *host_port, Error **errp)
> -- 
> 2.14.3
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK