Re: [PATCH net-next] net: hns: optimize XGE capability by reducing cpu usage

["Du, Fan" <fan.du@intel.com>]

On 2015/12/5 15:32, yankejian wrote:
> here is the patch raising the performance of XGE by:
> 1)changes the way page management method for enet momery, and
> 2)reduces the count of rmb, and
> 3)adds Memory prefetching

Any numbers on how much it boost performance?

> Signed-off-by: yankejian <yankejian@huawei.com>
> ---
>   drivers/net/ethernet/hisilicon/hns/hnae.h         |  5 +-
>   drivers/net/ethernet/hisilicon/hns/hns_ae_adapt.c |  1 -
>   drivers/net/ethernet/hisilicon/hns/hns_enet.c     | 79 +++++++++++++++--------
>   3 files changed, 55 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/net/ethernet/hisilicon/hns/hnae.h b/drivers/net/ethernet/hisilicon/hns/hnae.h
> index d1f3316..6ca94dc 100644
> --- a/drivers/net/ethernet/hisilicon/hns/hnae.h
> +++ b/drivers/net/ethernet/hisilicon/hns/hnae.h
> @@ -341,7 +341,8 @@ struct hnae_queue {
>   	void __iomem *io_base;
>   	phys_addr_t phy_base;
>   	struct hnae_ae_dev *dev;	/* the device who use this queue */
> -	struct hnae_ring rx_ring, tx_ring;
> +	struct hnae_ring rx_ring ____cacheline_internodealigned_in_smp;
> +	struct hnae_ring tx_ring ____cacheline_internodealigned_in_smp;
>   	struct hnae_handle *handle;
>   };
>
> @@ -597,11 +598,9 @@ static inline void hnae_replace_buffer(struct hnae_ring *ring, int i,
>   				       struct hnae_desc_cb *res_cb)
>   {
>   	struct hnae_buf_ops *bops = ring->q->handle->bops;
> -	struct hnae_desc_cb tmp_cb = ring->desc_cb[i];
>
>   	bops->unmap_buffer(ring, &ring->desc_cb[i]);
>   	ring->desc_cb[i] = *res_cb;
> -	*res_cb = tmp_cb;
>   	ring->desc[i].addr = (__le64)ring->desc_cb[i].dma;
>   	ring->desc[i].rx.ipoff_bnum_pid_flag = 0;
>   }
> diff --git a/drivers/net/ethernet/hisilicon/hns/hns_ae_adapt.c b/drivers/net/ethernet/hisilicon/hns/hns_ae_adapt.c
> index 77c6edb..522b264 100644
> --- a/drivers/net/ethernet/hisilicon/hns/hns_ae_adapt.c
> +++ b/drivers/net/ethernet/hisilicon/hns/hns_ae_adapt.c
> @@ -341,7 +341,6 @@ void hns_ae_toggle_ring_irq(struct hnae_ring *ring, u32 mask)
>   	else
>   		flag = RCB_INT_FLAG_RX;
>
> -	hns_rcb_int_clr_hw(ring->q, flag);
>   	hns_rcb_int_ctrl_hw(ring->q, flag, mask);
>   }
>
> diff --git a/drivers/net/ethernet/hisilicon/hns/hns_enet.c b/drivers/net/ethernet/hisilicon/hns/hns_enet.c
> index cad2663..e2be510 100644
> --- a/drivers/net/ethernet/hisilicon/hns/hns_enet.c
> +++ b/drivers/net/ethernet/hisilicon/hns/hns_enet.c
> @@ -33,6 +33,7 @@
>
>   #define RCB_IRQ_NOT_INITED 0
>   #define RCB_IRQ_INITED 1
> +#define HNS_BUFFER_SIZE_2048 2048
>
>   #define BD_MAX_SEND_SIZE 8191
>   #define SKB_TMP_LEN(SKB) \
> @@ -491,13 +492,51 @@ static unsigned int hns_nic_get_headlen(unsigned char *data, u32 flag,
>   		return max_size;
>   }
>
> -static void
> -hns_nic_reuse_page(struct hnae_desc_cb *desc_cb, int tsize, int last_offset)
> +static void hns_nic_reuse_page(struct sk_buff *skb, int i,
> +			       struct hnae_ring *ring, int pull_len,
> +			       struct hnae_desc_cb *desc_cb)
>   {
> +	struct hnae_desc *desc;
> +	int truesize, size;
> +	int last_offset = 0;
> +
> +	desc = &ring->desc[ring->next_to_clean];
> +	size = le16_to_cpu(desc->rx.size);
> +
> +#if (PAGE_SIZE < 8192)
> +	if (hnae_buf_size(ring) == HNS_BUFFER_SIZE_2048) {
> +		truesize = hnae_buf_size(ring);
> +	} else {
> +		truesize = ALIGN(size, L1_CACHE_BYTES);
> +		last_offset = hnae_page_size(ring) - hnae_buf_size(ring);
> +	}
> +
> +#else
> +		truesize = ALIGN(size, L1_CACHE_BYTES);
> +		last_offset = hnae_page_size(ring) - hnae_buf_size(ring);
> +#endif
> +
> +	skb_add_rx_frag(skb, i, desc_cb->priv, desc_cb->page_offset + pull_len,
> +			size - pull_len, truesize - pull_len);
> +
>   	 /* avoid re-using remote pages,flag default unreuse */
>   	if (likely(page_to_nid(desc_cb->priv) == numa_node_id())) {
> +#if (PAGE_SIZE < 8192)
> +		if (hnae_buf_size(ring) == HNS_BUFFER_SIZE_2048) {
> +			/* if we are only owner of page we can reuse it */
> +			if (likely(page_count(desc_cb->priv) == 1)) {
> +				/* flip page offset to other buffer */
> +				desc_cb->page_offset ^= truesize;
> +
> +				desc_cb->reuse_flag = 1;
> +				/* bump ref count on page before it is given*/
> +				get_page(desc_cb->priv);
> +			}
> +			return;
> +		}
> +#endif
>   		/* move offset up to the next cache line */
> -		desc_cb->page_offset += tsize;
> +		desc_cb->page_offset += truesize;
>
>   		if (desc_cb->page_offset <= last_offset) {
>   			desc_cb->reuse_flag = 1;
> @@ -529,11 +568,10 @@ static int hns_nic_poll_rx_skb(struct hns_nic_ring_data *ring_data,
>   	struct hnae_desc *desc;
>   	struct hnae_desc_cb *desc_cb;
>   	unsigned char *va;
> -	int bnum, length, size, i, truesize, last_offset;
> +	int bnum, length, i;
>   	int pull_len;
>   	u32 bnum_flag;
>
> -	last_offset = hnae_page_size(ring) - hnae_buf_size(ring);
>   	desc = &ring->desc[ring->next_to_clean];
>   	desc_cb = &ring->desc_cb[ring->next_to_clean];
>
> @@ -555,17 +593,12 @@ static int hns_nic_poll_rx_skb(struct hns_nic_ring_data *ring_data,
>   		return -ENOMEM;
>   	}
>
> +	prefetchw(skb->data);
>   	length = le16_to_cpu(desc->rx.pkt_len);
>   	bnum_flag = le32_to_cpu(desc->rx.ipoff_bnum_pid_flag);
>   	priv->ops.get_rxd_bnum(bnum_flag, &bnum);
>   	*out_bnum = bnum;
>
> -	/* we will be copying header into skb->data in
> -	 * pskb_may_pull so it is in our interest to prefetch
> -	 * it now to avoid a possible cache miss
> -	 */
> -	prefetchw(skb->data);
> -
>   	if (length <= HNS_RX_HEAD_SIZE) {
>   		memcpy(__skb_put(skb, length), va, ALIGN(length, sizeof(long)));
>
> @@ -588,13 +621,7 @@ static int hns_nic_poll_rx_skb(struct hns_nic_ring_data *ring_data,
>   		memcpy(__skb_put(skb, pull_len), va,
>   		       ALIGN(pull_len, sizeof(long)));
>
> -		size = le16_to_cpu(desc->rx.size);
> -		truesize = ALIGN(size, L1_CACHE_BYTES);
> -		skb_add_rx_frag(skb, 0, desc_cb->priv,
> -				desc_cb->page_offset + pull_len,
> -				size - pull_len, truesize - pull_len);
> -
> -		hns_nic_reuse_page(desc_cb, truesize, last_offset);
> +		hns_nic_reuse_page(skb, 0, ring, pull_len, desc_cb);
>   		ring_ptr_move_fw(ring, next_to_clean);
>
>   		if (unlikely(bnum >= (int)MAX_SKB_FRAGS)) { /* check err*/
> @@ -604,13 +631,8 @@ static int hns_nic_poll_rx_skb(struct hns_nic_ring_data *ring_data,
>   		for (i = 1; i < bnum; i++) {
>   			desc = &ring->desc[ring->next_to_clean];
>   			desc_cb = &ring->desc_cb[ring->next_to_clean];
> -			size = le16_to_cpu(desc->rx.size);
> -			truesize = ALIGN(size, L1_CACHE_BYTES);
> -			skb_add_rx_frag(skb, i, desc_cb->priv,
> -					desc_cb->page_offset,
> -					size, truesize);
>
> -			hns_nic_reuse_page(desc_cb, truesize, last_offset);
> +			hns_nic_reuse_page(skb, i, ring, 0, desc_cb);
>   			ring_ptr_move_fw(ring, next_to_clean);
>   		}
>   	}
> @@ -750,9 +772,10 @@ recv:
>   	/* make all data has been write before submit */
>   	if (recv_pkts < budget) {
>   		ex_num = readl_relaxed(ring->io_base + RCB_REG_FBDNUM);
> -		rmb(); /*complete read rx ring bd number*/
> +
>   		if (ex_num > clean_count) {
>   			num += ex_num - clean_count;
> +			rmb(); /*complete read rx ring bd number*/
>   			goto recv;
>   		}
>   	}
> @@ -849,8 +872,11 @@ static int hns_nic_tx_poll_one(struct hns_nic_ring_data *ring_data,
>
>   	bytes = 0;
>   	pkts = 0;
> -	while (head != ring->next_to_clean)
> +	while (head != ring->next_to_clean) {
>   		hns_nic_reclaim_one_desc(ring, &bytes, &pkts);
> +		/* issue prefetch for next Tx descriptor */
> +		prefetch(&ring->desc_cb[ring->next_to_clean]);
> +	}
>
>   	NETIF_TX_UNLOCK(ndev);
>
> @@ -926,6 +952,7 @@ static int hns_nic_common_poll(struct napi_struct *napi, int budget)
>   			ring_data->ring, 0);
>
>   		ring_data->fini_process(ring_data);
> +		return 0;
>   	}
>
>   	return clean_complete;
>