netdev - Re: [PATCH bpf-next v4 02/17] xsk: Add API to check for available entries in FQ

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Message-ID: <CAJ+HfNhY0fMa2QiJJM0xnrzcPWw4ZYKoFjMrD03wfL0aKSnoyg@mail.gmail.com>
Date:   Thu, 13 Jun 2019 14:50:06 +0200
From:   Björn Töpel <bjorn.topel@...il.com>
To:     Maxim Mikityanskiy <maximmi@...lanox.com>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Björn Töpel <bjorn.topel@...el.com>,
        Magnus Karlsson <magnus.karlsson@...el.com>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Saeed Mahameed <saeedm@...lanox.com>,
        Jonathan Lemon <bsd@...com>,
        Tariq Toukan <tariqt@...lanox.com>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Maciej Fijalkowski <maciejromanfijalkowski@...il.com>
Subject: Re: [PATCH bpf-next v4 02/17] xsk: Add API to check for available
 entries in FQ

On Wed, 12 Jun 2019 at 20:05, Maxim Mikityanskiy <maximmi@...lanox.com> wrote:
>
> Add a function that checks whether the Fill Ring has the specified
> amount of descriptors available. It will be useful for mlx5e that wants
> to check in advance, whether it can allocate a bulk of RX descriptors,
> to get the best performance.
>

Acked-by: Björn Töpel <bjorn.topel@...el.com>

> Signed-off-by: Maxim Mikityanskiy <maximmi@...lanox.com>
> Reviewed-by: Tariq Toukan <tariqt@...lanox.com>
> Acked-by: Saeed Mahameed <saeedm@...lanox.com>
> ---
>  include/net/xdp_sock.h | 21 +++++++++++++++++++++
>  net/xdp/xsk.c          |  6 ++++++
>  net/xdp/xsk_queue.h    | 14 ++++++++++++++
>  3 files changed, 41 insertions(+)
>
> diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
> index ae0f368a62bb..b6f5ebae43a1 100644
> --- a/include/net/xdp_sock.h
> +++ b/include/net/xdp_sock.h
> @@ -77,6 +77,7 @@ int xsk_rcv(struct xdp_sock *xs, struct xdp_buff *xdp);
>  void xsk_flush(struct xdp_sock *xs);
>  bool xsk_is_setup_for_bpf_map(struct xdp_sock *xs);
>  /* Used from netdev driver */
> +bool xsk_umem_has_addrs(struct xdp_umem *umem, u32 cnt);
>  u64 *xsk_umem_peek_addr(struct xdp_umem *umem, u64 *addr);
>  void xsk_umem_discard_addr(struct xdp_umem *umem);
>  void xsk_umem_complete_tx(struct xdp_umem *umem, u32 nb_entries);
> @@ -99,6 +100,16 @@ static inline dma_addr_t xdp_umem_get_dma(struct xdp_umem *umem, u64 addr)
>  }
>
>  /* Reuse-queue aware version of FILL queue helpers */
> +static inline bool xsk_umem_has_addrs_rq(struct xdp_umem *umem, u32 cnt)
> +{
> +       struct xdp_umem_fq_reuse *rq = umem->fq_reuse;
> +
> +       if (rq->length >= cnt)
> +               return true;
> +
> +       return xsk_umem_has_addrs(umem, cnt - rq->length);
> +}
> +
>  static inline u64 *xsk_umem_peek_addr_rq(struct xdp_umem *umem, u64 *addr)
>  {
>         struct xdp_umem_fq_reuse *rq = umem->fq_reuse;
> @@ -146,6 +157,11 @@ static inline bool xsk_is_setup_for_bpf_map(struct xdp_sock *xs)
>         return false;
>  }
>
> +static inline bool xsk_umem_has_addrs(struct xdp_umem *umem, u32 cnt)
> +{
> +       return false;
> +}
> +
>  static inline u64 *xsk_umem_peek_addr(struct xdp_umem *umem, u64 *addr)
>  {
>         return NULL;
> @@ -200,6 +216,11 @@ static inline dma_addr_t xdp_umem_get_dma(struct xdp_umem *umem, u64 addr)
>         return 0;
>  }
>
> +static inline bool xsk_umem_has_addrs_rq(struct xdp_umem *umem, u32 cnt)
> +{
> +       return false;
> +}
> +
>  static inline u64 *xsk_umem_peek_addr_rq(struct xdp_umem *umem, u64 *addr)
>  {
>         return NULL;
> diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
> index a14e8864e4fa..b68a380f50b3 100644
> --- a/net/xdp/xsk.c
> +++ b/net/xdp/xsk.c
> @@ -37,6 +37,12 @@ bool xsk_is_setup_for_bpf_map(struct xdp_sock *xs)
>                 READ_ONCE(xs->umem->fq);
>  }
>
> +bool xsk_umem_has_addrs(struct xdp_umem *umem, u32 cnt)
> +{
> +       return xskq_has_addrs(umem->fq, cnt);
> +}
> +EXPORT_SYMBOL(xsk_umem_has_addrs);
> +
>  u64 *xsk_umem_peek_addr(struct xdp_umem *umem, u64 *addr)
>  {
>         return xskq_peek_addr(umem->fq, addr);
> diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
> index 88b9ae24658d..12b49784a6d5 100644
> --- a/net/xdp/xsk_queue.h
> +++ b/net/xdp/xsk_queue.h
> @@ -117,6 +117,20 @@ static inline u32 xskq_nb_free(struct xsk_queue *q, u32 producer, u32 dcnt)
>         return q->nentries - (producer - q->cons_tail);
>  }
>
> +static inline bool xskq_has_addrs(struct xsk_queue *q, u32 cnt)
> +{
> +       u32 entries = q->prod_tail - q->cons_tail;
> +
> +       if (entries >= cnt)
> +               return true;
> +
> +       /* Refresh the local pointer. */
> +       q->prod_tail = READ_ONCE(q->ring->producer);
> +       entries = q->prod_tail - q->cons_tail;
> +
> +       return entries >= cnt;
> +}
> +
>  /* UMEM queue */
>
>  static inline bool xskq_is_valid_addr(struct xsk_queue *q, u64 addr)
> --
> 2.19.1
>