Re: [Qemu-devel] [PATCH v2 1/5] net: spread hub on AioContexts

[Paolo Bonzini <pbonzini@redhat.com>]

Il 07/03/2013 03:53, Liu Ping Fan ha scritto:
> From: Liu Ping Fan <pingfank@linux.vnet.ibm.com>
> 
> Forward packet to other hub ports by their AioContext.
> 
> Signed-off-by: Liu Ping Fan <pingfank@linux.vnet.ibm.com>
> ---
>  hw/qdev-properties-system.c |    1 +
>  include/block/aio.h         |    1 +
>  include/net/net.h           |    5 +++++
>  include/net/queue.h         |   14 ++++++++++++++
>  main-loop.c                 |    5 +++++
>  net/hub.c                   |   33 ++++++++++++++++++++++++++++++---
>  net/net.c                   |    1 +
>  net/queue.c                 |    4 ++--
>  8 files changed, 59 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/qdev-properties-system.c b/hw/qdev-properties-system.c
> index ce3af22..587a335 100644
> --- a/hw/qdev-properties-system.c
> +++ b/hw/qdev-properties-system.c
> @@ -307,6 +307,7 @@ static void set_vlan(Object *obj, Visitor *v, void *opaque,
>                    name, prop->info->name);
>          return;
>      }
> +    hubport->info->bind_ctx(hubport, qemu_get_aio_context());
>      *ptr = hubport;
>  }
>  
> diff --git a/include/block/aio.h b/include/block/aio.h
> index 5b54d38..bcb5126 100644
> --- a/include/block/aio.h
> +++ b/include/block/aio.h
> @@ -229,6 +229,7 @@ bool qemu_aio_wait(void);
>  void qemu_aio_set_event_notifier(EventNotifier *notifier,
>                                   EventNotifierHandler *io_read,
>                                   AioFlushEventNotifierHandler *io_flush);
> +AioContext *qemu_get_aio_context(void);
>  
>  #ifdef CONFIG_POSIX
>  void qemu_aio_set_fd_handler(int fd,
> diff --git a/include/net/net.h b/include/net/net.h
> index cb049a1..9c2b357 100644
> --- a/include/net/net.h
> +++ b/include/net/net.h
> @@ -8,6 +8,9 @@
>  #include "net/queue.h"
>  #include "migration/vmstate.h"
>  #include "qapi-types.h"
> +#include "qemu/thread.h"
> +#include "block/aio.h"
> +
>  
>  #define MAX_QUEUE_NUM 1024
>  
> @@ -44,6 +47,7 @@ typedef ssize_t (NetReceiveIOV)(NetClientState *, const struct iovec *, int);
>  typedef void (NetCleanup) (NetClientState *);
>  typedef void (LinkStatusChanged)(NetClientState *);
>  typedef void (NetClientDestructor)(NetClientState *);
> +typedef void (NetClientBindCtx)(NetClientState *, AioContext *);
>  
>  typedef struct NetClientInfo {
>      NetClientOptionsKind type;
> @@ -55,6 +59,7 @@ typedef struct NetClientInfo {
>      NetCleanup *cleanup;
>      LinkStatusChanged *link_status_changed;
>      NetPoll *poll;
> +    NetClientBindCtx *bind_ctx;
>  } NetClientInfo;
>  
>  struct NetClientState {
> diff --git a/include/net/queue.h b/include/net/queue.h
> index fc02b33..f60e57f 100644
> --- a/include/net/queue.h
> +++ b/include/net/queue.h
> @@ -38,6 +38,20 @@ NetQueue *qemu_new_net_queue(void *opaque);
>  
>  void qemu_del_net_queue(NetQueue *queue);
>  
> +void qemu_net_queue_append(NetQueue *queue,
> +                                  NetClientState *sender,
> +                                  unsigned flags,
> +                                  const uint8_t *buf,
> +                                  size_t size,
> +                                  NetPacketSent *sent_cb);
> +
> +void qemu_net_queue_append_iov(NetQueue *queue,
> +                                      NetClientState *sender,
> +                                      unsigned flags,
> +                                      const struct iovec *iov,
> +                                      int iovcnt,
> +                                      NetPacketSent *sent_cb);
> +
>  ssize_t qemu_net_queue_send(NetQueue *queue,
>                              NetClientState *sender,
>                              unsigned flags,
> diff --git a/main-loop.c b/main-loop.c
> index 8c9b58c..eb80ff3 100644
> --- a/main-loop.c
> +++ b/main-loop.c
> @@ -109,6 +109,11 @@ static int qemu_signal_init(void)
>  
>  static AioContext *qemu_aio_context;
>  
> +AioContext *qemu_get_aio_context(void)
> +{
> +    return qemu_aio_context;
> +}
> +
>  void qemu_notify_event(void)
>  {
>      if (!qemu_aio_context) {
> diff --git a/net/hub.c b/net/hub.c
> index df32074..73c1f26 100644
> --- a/net/hub.c
> +++ b/net/hub.c
> @@ -31,6 +31,8 @@ typedef struct NetHubPort {
>      QLIST_ENTRY(NetHubPort) next;
>      NetHub *hub;
>      int id;
> +    EventNotifier e;
> +    AioContext *ctx;
>  } NetHubPort;
>  
>  struct NetHub {
> @@ -52,11 +54,20 @@ static ssize_t net_hub_receive(NetHub *hub, NetHubPort *source_port,
>              continue;
>          }
>  
> -        qemu_send_packet(&port->nc, buf, len);
> +        qemu_net_queue_append(port->nc.peer->send_queue, &port->nc,
> +                            QEMU_NET_PACKET_FLAG_NONE, buf, len, NULL);
> +        event_notifier_set(&port->e);

Why are the context and the EventNotifier a property of the port, rather
than applicable to the NetClientState?

Please explain the design and where you want to go.  We do not have a
crystal ball :) and lack of explanation can only prevent people from
looking at your patches.

The absolute best would be if every tiny step along the way provides a
benefit.  For example, the patches that introduced AioContext enabled
asynchronous I/O on Windows.  Without such an incentive, it is very
difficult that patches progress beyond the RFC phase.

Paolo

>      }
>      return len;
>  }
>  
> +static void hub_port_deliver_packet(void *opaque)
> +{
> +    NetHubPort *port = (NetHubPort *)opaque;
> +
> +    qemu_net_queue_flush(port->nc.peer->send_queue);
> +}
> +
>  static ssize_t net_hub_receive_iov(NetHub *hub, NetHubPort *source_port,
>                                     const struct iovec *iov, int iovcnt)
>  {
> @@ -68,7 +79,9 @@ static ssize_t net_hub_receive_iov(NetHub *hub, NetHubPort *source_port,
>              continue;
>          }
>  
> -        qemu_sendv_packet(&port->nc, iov, iovcnt);
> +        qemu_net_queue_append_iov(port->nc.peer->send_queue, &port->nc,
> +                            QEMU_NET_PACKET_FLAG_NONE, iov, iovcnt, NULL);
> +        event_notifier_set(&port->e);
>      }
>      return len;
>  }
> @@ -126,9 +139,22 @@ static void net_hub_port_cleanup(NetClientState *nc)
>  {
>      NetHubPort *port = DO_UPCAST(NetHubPort, nc, nc);
>  
> +    if (port->ctx) {
> +        aio_set_fd_handler(port->ctx, event_notifier_get_fd(&port->e),
> +                        NULL, NULL, NULL, NULL);
> +    }
>      QLIST_REMOVE(port, next);
>  }
>  
> +static void net_hub_port_bind_ctx(NetClientState *nc, AioContext *ctx)
> +{
> +    NetHubPort *port = DO_UPCAST(NetHubPort, nc, nc);
> +
> +    port->ctx = ctx;
> +    aio_set_fd_handler(ctx, event_notifier_get_fd(&port->e),
> +                        hub_port_deliver_packet, NULL, NULL, port);
> +}
> +
>  static NetClientInfo net_hub_port_info = {
>      .type = NET_CLIENT_OPTIONS_KIND_HUBPORT,
>      .size = sizeof(NetHubPort),
> @@ -136,6 +162,7 @@ static NetClientInfo net_hub_port_info = {
>      .receive = net_hub_port_receive,
>      .receive_iov = net_hub_port_receive_iov,
>      .cleanup = net_hub_port_cleanup,
> +    .bind_ctx = net_hub_port_bind_ctx,
>  };
>  
>  static NetHubPort *net_hub_port_new(NetHub *hub, const char *name)
> @@ -155,7 +182,7 @@ static NetHubPort *net_hub_port_new(NetHub *hub, const char *name)
>      port = DO_UPCAST(NetHubPort, nc, nc);
>      port->id = id;
>      port->hub = hub;
> -
> +    event_notifier_init(&port->e, 0);
>      QLIST_INSERT_HEAD(&hub->ports, port, next);
>  
>      return port;
> diff --git a/net/net.c b/net/net.c
> index f3d67f8..104c5b2 100644
> --- a/net/net.c
> +++ b/net/net.c
> @@ -781,6 +781,7 @@ static int net_client_init1(const void *object, int is_netdev, Error **errp)
>              (opts->kind != NET_CLIENT_OPTIONS_KIND_NIC ||
>               !opts->nic->has_netdev)) {
>              peer = net_hub_add_port(u.net->has_vlan ? u.net->vlan : 0, NULL);
> +            peer->info->bind_ctx(peer, qemu_get_aio_context());
>          }
>  
>          if (net_client_init_fun[opts->kind](opts, name, peer) < 0) {
> diff --git a/net/queue.c b/net/queue.c
> index 859d02a..67959f8 100644
> --- a/net/queue.c
> +++ b/net/queue.c
> @@ -87,7 +87,7 @@ void qemu_del_net_queue(NetQueue *queue)
>      g_free(queue);
>  }
>  
> -static void qemu_net_queue_append(NetQueue *queue,
> +void qemu_net_queue_append(NetQueue *queue,
>                                    NetClientState *sender,
>                                    unsigned flags,
>                                    const uint8_t *buf,
> @@ -110,7 +110,7 @@ static void qemu_net_queue_append(NetQueue *queue,
>      QTAILQ_INSERT_TAIL(&queue->packets, packet, entry);
>  }
>  
> -static void qemu_net_queue_append_iov(NetQueue *queue,
> +void qemu_net_queue_append_iov(NetQueue *queue,
>                                        NetClientState *sender,
>                                        unsigned flags,
>                                        const struct iovec *iov,
>