On Wed, 2016-10-19 at 14:47 +0200, Paolo Abeni wrote:
> Completely avoid default sock memory accounting and replace it
> with udp-specific accounting.
>
> Since the new memory accounting model encapsulates completely
> the required locking, remove the socket lock on both enqueue and
> dequeue, and avoid using the backlog on enqueue.
>
> Be sure to clean-up rx queue memory on socket destruction, using
> udp its own sk_destruct.
>
> Tested using pktgen with random src port, 64 bytes packet,
> wire-speed on a 10G link as sender and udp_sink as the receiver,
> using an l4 tuple rxhash to stress the contention, and one or more
> udp_sink instances with reuseport.
>
> nr readers Kpps (vanilla) Kpps (patched)
> 1 170 420
> 3 1250 1900
> 6 3000 3500
> 9 4200 4400
> 12 5700 6100
>
> v3 -> v4:
> - remove useless sk_rcvqueues_full() call
>
> v2 -> v3:
> - do not set the now unsed backlog_rcv callback
>
> v1 -> v2:
> - add memory pressure support
> - fixed dropwatch accounting for ipv6
>
> Acked-by: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
> ---
> net/ipv4/udp.c | 42 ++++++++----------------------------------
> net/ipv6/udp.c | 34 ++++++++--------------------------
> net/sunrpc/svcsock.c | 20 ++++++++++++++++----
> net/sunrpc/xprtsock.c | 2 +-
> 4 files changed, 33 insertions(+), 65 deletions(-)
>
> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> index 7047bb3..1925ca7 100644
> --- a/net/ipv4/udp.c
> +++ b/net/ipv4/udp.c
> @@ -1312,13 +1312,8 @@ static int first_packet_length(struct sock *sk)
> res = skb ? skb->len : -1;
> spin_unlock_bh(&rcvq->lock);
>
> - if (!skb_queue_empty(&list_kill)) {
> - bool slow = lock_sock_fast(sk);
> -
> + if (!skb_queue_empty(&list_kill))
> __skb_queue_purge(&list_kill);
> - sk_mem_reclaim_partial(sk);
> - unlock_sock_fast(sk, slow);
> - }
Simply call __skb_queue_purge(&list_kill);
(without testing if list_kill is empty or not)
> return res;
> }
>
We also could remove list_kill and directly call kfree_skb() in the
loop.
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