[ovs-dev] [PATCH 2/2] dpif-netdev: Eliminate two malloc() calls per packet sent to "userspace".

[Ed Maste]

On 15 August 2012 19:12, Ben Pfaff <blp at nicira.com> wrote:
> This is easy enough, so it seems worthwhile now that FreeBSD is starting
> to make more use of the "userspace switch".
>
> CC: Ed Maste <emaste at freebsd.org>
> Signed-off-by: Ben Pfaff <blp at nicira.com>
> ---
>  lib/dpif-netdev.c |   33 +++++++++++++++++++--------------
>  1 files changed, 19 insertions(+), 14 deletions(-)
>
> diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
> index 3d01b17..144b6b6 100644
> --- a/lib/dpif-netdev.c
> +++ b/lib/dpif-netdev.c
> @@ -70,8 +70,13 @@ enum { MAX_QUEUE_LEN = 128 };   /* Maximum number of packets per queue. */
>  enum { QUEUE_MASK = MAX_QUEUE_LEN - 1 };
>  BUILD_ASSERT_DECL(IS_POW2(MAX_QUEUE_LEN));
>
> +struct dp_netdev_upcall {
> +    struct dpif_upcall upcall;  /* Queued upcall information. */
> +    struct ofpbuf buf;          /* ofpbuf instance for upcall.packet. */
> +};
> +
>  struct dp_netdev_queue {
> -    struct dpif_upcall *upcalls[MAX_QUEUE_LEN];
> +    struct dp_netdev_upcall upcalls[MAX_QUEUE_LEN];
>      unsigned int head, tail;
>  };
>
> @@ -259,10 +264,8 @@ dp_netdev_purge_queues(struct dp_netdev *dp)
>          struct dp_netdev_queue *q = &dp->queues[i];
>
>          while (q->tail != q->head) {
> -            struct dpif_upcall *upcall = q->upcalls[q->tail++ & QUEUE_MASK];
> -
> -            ofpbuf_delete(upcall->packet);
> -            free(upcall);
> +            struct dp_netdev_upcall *u = &q->upcalls[q->tail++ & QUEUE_MASK];
> +            ofpbuf_uninit(&u->buf);
>          }
>      }
>  }
> @@ -960,13 +963,13 @@ dpif_netdev_recv(struct dpif *dpif, struct dpif_upcall *upcall,
>  {
>      struct dp_netdev_queue *q = find_nonempty_queue(dpif);
>      if (q) {
> -        struct dpif_upcall *u = q->upcalls[q->tail++ & QUEUE_MASK];
> -        *upcall = *u;
> -        free(u);
> +        struct dp_netdev_upcall *u = &q->upcalls[q->tail++ & QUEUE_MASK];
> +
> +        *upcall = u->upcall;
> +        upcall->packet = buf;

Doesn't upcall->key still point into the static buf from upcalls[] in this case?

-Ed