Hi Lorenzo,
On Tue, Oct 27, 2020 at 08:04:07PM +0100, Lorenzo Bianconi wrote:
> Introduce bulking capability in xdp tx return path (XDP_REDIRECT).
> xdp_return_frame is usually run inside the driver NAPI tx completion
> loop so it is possible batch it.
> Current implementation considers only page_pool memory model.
> Convert mvneta driver to xdp_return_frame_bulk APIs.
>
> Suggested-by: Jesper Dangaard Brouer <bro...@redhat.com>
> Signed-off-by: Lorenzo Bianconi <lore...@kernel.org>
> ---
> drivers/net/ethernet/marvell/mvneta.c | 5 ++-
> include/net/xdp.h | 9 +++++
> net/core/xdp.c | 51 +++++++++++++++++++++++++++
> 3 files changed, 64 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/marvell/mvneta.c
> b/drivers/net/ethernet/marvell/mvneta.c
> index 54b0bf574c05..43ab8a73900e 100644
> --- a/drivers/net/ethernet/marvell/mvneta.c
> +++ b/drivers/net/ethernet/marvell/mvneta.c
> @@ -1834,8 +1834,10 @@ static void mvneta_txq_bufs_free(struct mvneta_port
> *pp,
> struct netdev_queue *nq, bool napi)
> {
> unsigned int bytes_compl = 0, pkts_compl = 0;
> + struct xdp_frame_bulk bq;
> int i;
>
> + bq.xa = NULL;
> for (i = 0; i < num; i++) {
> struct mvneta_tx_buf *buf = &txq->buf[txq->txq_get_index];
> struct mvneta_tx_desc *tx_desc = txq->descs +
> @@ -1857,9 +1859,10 @@ static void mvneta_txq_bufs_free(struct mvneta_port
> *pp,
> if (napi && buf->type == MVNETA_TYPE_XDP_TX)
> xdp_return_frame_rx_napi(buf->xdpf);
> else
> - xdp_return_frame(buf->xdpf);
> + xdp_return_frame_bulk(buf->xdpf, &bq);
> }
> }
> + xdp_flush_frame_bulk(&bq);
>
> netdev_tx_completed_queue(nq, pkts_compl, bytes_compl);
> }
> diff --git a/include/net/xdp.h b/include/net/xdp.h
> index 3814fb631d52..9567110845ef 100644
> --- a/include/net/xdp.h
> +++ b/include/net/xdp.h
> @@ -104,6 +104,12 @@ struct xdp_frame {
> struct net_device *dev_rx; /* used by cpumap */
> };
>
> +#define XDP_BULK_QUEUE_SIZE 16
> +struct xdp_frame_bulk {
> + void *q[XDP_BULK_QUEUE_SIZE];
> + int count;
> + void *xa;
> +};
>
> static inline struct skb_shared_info *
> xdp_get_shared_info_from_frame(struct xdp_frame *frame)
> @@ -194,6 +200,9 @@ struct xdp_frame *xdp_convert_buff_to_frame(struct
> xdp_buff *xdp)
> void xdp_return_frame(struct xdp_frame *xdpf);
> void xdp_return_frame_rx_napi(struct xdp_frame *xdpf);
> void xdp_return_buff(struct xdp_buff *xdp);
> +void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq);
> +void xdp_return_frame_bulk(struct xdp_frame *xdpf,
> + struct xdp_frame_bulk *bq);
>
> /* When sending xdp_frame into the network stack, then there is no
> * return point callback, which is needed to release e.g. DMA-mapping
> diff --git a/net/core/xdp.c b/net/core/xdp.c
> index 48aba933a5a8..93eabd789246 100644
> --- a/net/core/xdp.c
> +++ b/net/core/xdp.c
> @@ -380,6 +380,57 @@ void xdp_return_frame_rx_napi(struct xdp_frame *xdpf)
> }
> EXPORT_SYMBOL_GPL(xdp_return_frame_rx_napi);
>
> +void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq)
> +{
> + struct xdp_mem_allocator *xa = bq->xa;
> + int i;
> +
> + if (unlikely(!xa))
> + return;
> +
> + for (i = 0; i < bq->count; i++) {
> + struct page *page = virt_to_head_page(bq->q[i]);
> +
> + page_pool_put_full_page(xa->page_pool, page, false);
> + }
> + bq->count = 0;
> +}
> +EXPORT_SYMBOL_GPL(xdp_flush_frame_bulk);
> +
> +void xdp_return_frame_bulk(struct xdp_frame *xdpf,
> + struct xdp_frame_bulk *bq)
> +{
> + struct xdp_mem_info *mem = &xdpf->mem;
> + struct xdp_mem_allocator *xa, *nxa;
> +
> + if (mem->type != MEM_TYPE_PAGE_POOL) {
> + __xdp_return(xdpf->data, &xdpf->mem, false);
> + return;
> + }
> +
> + rcu_read_lock();
> +
> + xa = bq->xa;
> + if (unlikely(!xa || mem->id != xa->mem.id)) {
Why is this marked as unlikely? The driver passes it as NULL. Should unlikely be
checked on both xa and the comparison?
> + nxa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
Is there a chance nxa can be NULL?
> + if (unlikely(!xa)) {
Same here, driver passes it as NULL
> + bq->count = 0;
> + bq->xa = nxa;
> + xa = nxa;
> + }
> + }
> +
> + if (mem->id != xa->mem.id || bq->count == XDP_BULK_QUEUE_SIZE)
> + xdp_flush_frame_bulk(bq);
> +
> + bq->q[bq->count++] = xdpf->data;
> + if (mem->id != xa->mem.id)
> + bq->xa = nxa;
> +
> + rcu_read_unlock();
> +}
> +EXPORT_SYMBOL_GPL(xdp_return_frame_bulk);
> +
> void xdp_return_buff(struct xdp_buff *xdp)
> {
> __xdp_return(xdp->data, &xdp->rxq->mem, true);
> --
> 2.26.2
>
Cheers
/Ilias
